prod_norms

ASIST Information Service Technical Brief No 2

Productivity Norms for labour-based construction

Inter nat ional ional Labour Organisat ion ion ADVISORY SUPPORT, INFORMATION SERVICES, AN AND D T RAINING (ASIST) Nairobi, Kenya

The Employment Employment -Intensive Progra Progra mm e (EIP (EIP ) is a sub-programm sub-programm e within within th e Development Development Policies Policies Depar tm ent (POLDEV) of of the ILO. Its objec objective tive is t o promote th e use of local local resource based t echnolo echnologie giess in infrast ru cture works in developing developing count count ries an d to str engthen th eir capacity to apply such technologies. technologies. ASIST is a su b-regional b-regional program me u nder the EIP , one one of whose whose objec objectives tives is to achieve an improved effectiv effectiveness eness of road const const ru ction, ction, r ehabilitat ion ion a nd maintena nce in Sub-Sahara n Africa Africa and thereby promote promote employment employment and inco income generation generation in the rura l and urban areas. The a im of ASIST ASIST Technical Briefs is to sprea d kn owledge owledge about about labour-based technology technology and m ana gement a mongst polic policy y maker s, planner s, designer designer s, implementers implementers and t rainers.

The Employment Employment -Intensive Progra Progra mm e (EIP (EIP ) is a sub-programm sub-programm e within within th e Development Development Policies Policies Depar tm ent (POLDEV) of of the ILO. Its objec objective tive is t o promote th e use of local local resource based t echnolo echnologie giess in infrast ru cture works in developing developing count count ries an d to str engthen th eir capacity to apply such technologies. technologies. ASIST is a su b-regional b-regional program me u nder the EIP , one one of whose whose objec objectives tives is to achieve an improved effectiv effectiveness eness of road const const ru ction, ction, r ehabilitat ion ion a nd maintena nce in Sub-Sahara n Africa Africa and thereby promote promote employment employment and inco income generation generation in the rura l and urban areas. The a im of ASIST ASIST Technical Briefs is to sprea d kn owledge owledge about about labour-based technology technology and m ana gement a mongst polic policy y maker s, planner s, designer designer s, implementers implementers and t rainers.

Productivity Norms for labour-based construction First edition

This publication was developed by the ASIST technical team in Harare, Zimbabwe, and Nairobi, Kenya. Written by David Stiedl, from original material collected and collated by Ulf Brudefors and Mike Shone. Editing and layout by David Mason.

International Labour Organisation Organisation Advisory Support, Information Services, and Training (ASIST) Nairobi, Kenya

Copyright

© Intern ational

Labour Labour Organisation Organisation 1998 1998

Pu blicatio blications ns of the Int erna tional Labour Or ganisat ion ion en joy joy copyright copyright un der P rotocol rotocol 2 of th e Universal Copyright Copyright Convention. Convention. Nevertheless, short excerpts from th em ma y be repr oduced oduced without aut horisation, on on condition condition tha t th e sour sour ce is indicat indicat ed. For For r ights of repr oduction, oduction, adapt at ion ion or tra nsla tion, applicat applicat ion ion should be made to the ILO/ASIST ILO/ASIST I nforma tion Ser vice, vice, PO Box 60598, Nairobi, Kenya, or or t o ILO Publications Bra nch (Rights (Rights a nd P erm issions), issions), Inter na tional Labour Offic Office, e, CH-1211 CH-1211 Geneva Geneva 22, Switzerland. Both ASIST an d th e Int ern ational Labour Offi Office ce welc welcome ome such applications.

Technical Brief No. 2: Productivity norms for labour-based construction First published 1998

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The designat ions ions employed employed in ILO pu blicat blicat ions, ions, which ar e in conformity conformity with United Nat ions ions pr actice, an d the presen ta tion of of ma ter ial ther ein, do not imply th e expression expression of any opinion opinion wh atsoever on the part of the Inter nat ional ional La bour bour Offi Office ce conc concerning erning t he legal statu s of any count count ry, area or terr itory or or of its its a uth orities, or conc concerning erning th e delimitat ion ion of its frontiers . The r esponsibility esponsibility for for opinions expressed in signed art icles, icles, studies studies a nd other contr contr ibutions ibutions rests solel solely y with th eir au thors, and publicat publicat ion ion does not constitut constitut e an en dorsement by the Int ern at ional ional Labour Office Office of of th e opinions opinions expressed in t hem. Reference to nam es of firm firm s an d comm comm ercial products an d processes processes does not not imply their en dorsement by the Int erna tional Labour Offic Office, e, an d any failure to ment ion ion a pa rt icular icular firm firm , commercial commercial product or or pr ocess ocess is not a sign of disapproval. Th is is not an official official ILO d ocum ocum ent

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ILO/ASIST Technical Brief No. 2: Productivity Norms

Contents L i s t of T a b le s ...............................................................................4 Ack n ow le d ge m e n t s ....................................................................5 Ab b r e v ia t io n s ..............................................................................6 1

In t r od u c t io n ...........................................................................7

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D e f i n i t i o n s f o r l a b o u r -b a s e d c o n s t r u c t i o n .................1 0

2.1 TYPICAL ACTIVITIES ............................................................................................10 2.1.1 S ite clearing ...........................................................................11 2.1.2 Excavation .............................................................................12 2.1.3 Hauling..................................................................................13 2.1.4 Loading, un loading and spreading ..........................................14 2.1.5 Com paction ............................................................................15 2.1.6 Culvert laying.........................................................................16

2.2 WORK METHODS ..................................................................................................17

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P r od u ct iv it y n or m s ............................................................19

3.1 S ITE CLEARING .....................................................................................................19 3.2 EXCAVATION .........................................................................................................20 3.3 H AULAGE ...............................................................................................................22 3.4 LOADING , UNLOADING AND SPREADING ......................................................23 3.5 COMPACTION ........................................................................................................24 3.6 CULVERT LAYING ................................................................................................25 3.7 AN EXAMPLE OF COMBINED ACTIVITIES ......................................................25 3.8 S UMMARIES ...........................................................................................................26

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F a ct or s a ffect in g p r od u ct ivi t y........................................29

4.1 MOTIVATION AND EXPERIEN CE OF TH E WORKFORCE ............................29 4.2 ORGANISATION OF TH E WORK ........................................................................31 4.3 TOOLS AND EQUIPMEN T SPE CIFICATION AND MAINTENANCE .............33 4.4 MONITORING NORMS .........................................................................................34

AN N E X 1 : R e fe r e n c e s .............................................................37 GENERAL ........................................................................................................................37 U SED F OR PRODUCTIVITY RATES ...........................................................................37

ANNE X 2: Co u n t r y p r od u ct ivi t y d a t a .................................40 COUNTRY DATA FOR SITE CLEARING ACTIVITIES .............................................40 COUNTRY DATA FOR E XCAVATION ACTIVITIES ..................................................41 COUNTRY DATA FOR H AULAGE ACTIVITIE S ........................................................42 COUNT RY DATA FOR LOADING , UNLOADING AND SPREADING ACTIVITIES .............................................................................................................43 COUNTRY DATA FOR COMPACTION ACTIVITIE S .................................................44 COUNTRY DATA FOR CULVERT LAYING ACTIVITIES .........................................45

AN N E X 3 : L a b o u r p r o d u c t i v i t i e s i n c o n s t r u c t i o n w or k s — a h ist or ica l p er sp e ct ive ..................................46


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List of Tables Ta ble 1: Bu sh clear in g ch a ra cter ist ics..................................... 11 Ta ble 2 : Soil excava t ion ch ar a cter ist ics .................................. 13 Table 3: Ha u lage equip men t char acter istics .......................... 14 Table 4: Tools for loadin g, un loadin g an d sp rea din g............. 15 Ta ble 5: Tools an d equ ipm en t for comp a ction ........................ 16 Ta ble 6: Tools for cul ver t la yin g ............................................... 17 Table 7: Sit e clear ing norm s – coun tr y d at a ........................... 20 Table 8: Site clearin g norm s – recommen ded va lues............. 20 Ta ble 9: Excava t ion n orm s – cou n t ry d at a .............................. 20 Table 10: Excava tion n orms – recommen ded valu es ............. 21 Table 11: Wheelbarr ow hau lage norms – coun tr y dat a ......... 22 Table 12: Wheelbarr ow ha ula ge norms – recomm ended va lu es ..................................................................................... 22 Table 13: Typical h au lage rat es for ma nu ally loaded eq u ip m en t .............................................................................. 23 Table 14: Loading, un loading a nd s pread ing norms – cou n t r y d a t a .......................................................................... 23 Table 15: Loading, un loading a nd s pread ing norms – r ecomm en de d va lu es ............................................................ 24 Table 16: Compa ction norms – coun tr y data an d r ecomm en de d va lu es ............................................................ 24 Table 17: Cu lvert laying norm s – coun tr y da ta ...................... 25 Table 18: Culvert la ying norm s – recomm ended values........ 25 Table 19: Typical equipm ent /labou r combin at ions for gr a ve llin g ............................................................................... 26 Ta ble 20: Su mm ar y of re comm en ded va lue s ........................... 26 Ta ble 21: Obser va t ions on wor ke r ou t pu t ............................... 29 Table 22: Average worker inpu t for complet ed op er a t ion s .............................................................................. 36

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Acknowledgements This docum ent is par t of an occasiona l series of techn ical briefs produced by ILO/ASIST to synth esise and su mm ar ise techn ical inform at ion on importa nt asp ects of labour-based technology. The original resear ch an d informa tion acquisition is th e work of Mike Shone a nd Ulf Bru defors , who also produced a subs ta nt ive first d ra ft. David St iedl was respons ible for revising a nd editing t his dra ft t o take a ccoun t of commen ts received from a nu mber of key practitioners an d senior ILO staff. We also wish to th an k Gar y Taylor for t he h istorical per spective of labour produ ctivities in cons tr uction works (Ann ex 3), and th e ma ny pr oject st aff who took t he t ime to an swer the detailed questionn aires, th us ensur ing th e docum ent its pr actical r elevan ce.


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Abbreviations AS IS T CTP DF R E LH U K IH AB T KTC LCU LBDU MART MRP TRL RARP USD WB

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Ad vis or y S u pp or t , I n for m a t ion Se rvice s a n d Tra ining for labour-based t echn ology Con st r u ct ion Tech nology P a p er Dep a r t m en t of F eed er Roa d s E xca va te, Loa d, H au l, Un loa d K en y a I n st i t u t e of H i gh w a ys a n d B u ild in g Technology Kisii Tr a in in g Cen t r e La bou r Con st r u ct ion U n it La bou r-ba sed Developm en t U nit Ma n agem en t of Ap pr op ria t e Roa dwor k s Technology Min or Roa d P r ogr a m m e Tr a n spor t Res ea r ch La bor a t or y Ru r a l Access Roa d P rogr am me U n it ed St a t es Dolla r s Wor ld Ba n k


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Introduction All civil engin eerin g projects rely on th e pr oductivity of th eir equipment an d workers t o achieve good r esults. Major capita l work s projects with a h igh element of equipm ent can estimate with some accur acy how much and what kind of equipment will be required for t he t ype of work envisaged. Estima ting man uals such as th e Caterpillar Performa nce Ha ndbook pr ovide work out put s for most common equipment types (based on t he assu mpt ion th at t hey are properly ut ilised), an d th ese figures form th e basis of all cost an d tim e estimat es. Individual labour pr oductivity, while importan t to ensu re equ ipmen t is u tilised effectively, will ha ve a min or impa ct on overall costs an d timin g. Labour-based p rojects however a re a lmost entirely dependent on th e productivity of labour . Provided th e worker s are properly organ ised and sup plied with th e corr ect ha nd tools, th ey will be able to car ry out m ost of th e activities us ua lly done by ear th moving machiner y. However, it is essent ial to have rea listic estim at es of expected labour productivity in order to plan an d carry out labour -based work effectively. The first action of an y plann ing engineer on a labour-based project sh ould be to determine th e quan tities an d type of work to be car ried out. The engineer sh ould then divide th is work into activities tha t can be car ried out by individuals or groups of work ers, an d th en, by app lying work norm s, determ ine th e required labour force and th e dura tion of th e pr oject. Choosing the corr ect work n orm is th e most critical par t of this pr ocess. As a very simp le exam ple, one kilomet re of dr ain age ditch t o be excava ted for a pipeline could be considered a s only one activity, i.e. excavat ion. If it is known th at th e average am ount of ma ter ial to be excavat ed is 2m³ in volum e per metr e length of ditch, an d th e productivity norm of th e workers is set a t 3m ³ per day, th en t he pr oject could be completed in one da y with 667 workers. At th e other extreme, it would ta ke about t hr ee years with one worker. A more t ypical set -up would be a group of 48 worker s deployed over 14 da ys. The critical figure is th e productivity n orm . Worker s a re commonly set task s in labour-based works th at equal th ese norms. If th e task is underestima ted by 30 per cent, i.e. 2m³ a day for excavation r ath er th an 3m 3 in th e example above, the direct cost of th e pr oject will increas e by 30 per cent . Conversely, if the ta sks a re overestimat ed, then much of th e workforce will not be a ble to meet its ta rgets a nd t her e will be considerable disrupt ion a nd discontent on site. Est imat ing th e correct pr oductivity is probably th e most import an t decision for the en gineer. If th e physical qua nt ities are wrongly estimat ed th is can be corrected on remeasu remen t. If th e nu mber of people recru ited are insu fficient t his can a lso be easily rectified; but alt ering t he


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norms significan tly at a lat er st age involves convincing work ers t o do more work for th e sam e money, which can be very difficult , an d n ot cond ucive to su ccess in a labour dependen t pr oject. Fortu na tely, th ere ha s been a lot of work done on deter min ing rea listic work norm s for differen t a ctivities in differen t situ at ions . It should th erefore be possible for a p l a n n i n g e n g in e e r t o d r a w u p on t h a t e xp e r i en c e a t t h e s t a r t of an y project, with t he confidence tha t it is th e correct order of magnitu de and tha t it can be fine-tu ned as work progresses. Unfort un at ely, mu ch of th is dat a is difficult t o find, an d often relates to very par ticular circum sta nces, with un ique project assu mptions. It can th erefore be qu ite misleading to simply apply such n orms without a full ap preciat ion of th e project an d project organ isat ion from w h e r e t h e d a t a ca m e . ASIST h as been involved in pr oject des ign an d monitorin g of labour-based program mes for a decade, and h as a ccess to project r eport s a nd dat a from projects all over th e world. It ha s t herefore been decided to look at all cur rent ly available data an d ma ke a synth esis of prevailing productivity norms to allow th e project plan ner t o have a better ha ndle on wh at is most a ppropriat e for h is or h er us e. Even th is synthesis will have its limitations, an d it is import an t to appreciat e tha t th ese are productivities that can be expected u nder ideal circum sta nces. That is, the workforce is well organ ised and s upervised, underst an ds th e work it is sup posed t o do, and ha s t he corr ect h an dtools in good condition. P oor t ools or poor organ isat ion can ea sily ha lve the workers’ out put . It is also assu med th at th e worker is healthy, properly paid, working n orma l hours, and ha s good access t o food a nd wat er. The issues of worker conditions and labour man agement ar e not covered in t his guideline a s it is assu med t ha t t hey will be properly applied. However, th e reader is referred t o the ILO publication E mployment-Intensive Infrastr ucture Pr ogra mm es: Labour p olicies and p ra ctices 1 , which covers th is subject compr ehen sively. This Brief is t ar geted at professiona l sta ff, either en gineers or technicians, who ha ve experien ce of road cons tr uction an d main tena nce activities a nd some exposur e to th e concepts an d ap plicat ion of labour-based t echn ology. It does not aim t o be a primer in engineering techn iques or labour-based techn ology. The rea der is referred t o th e ASIST Source Book 2 for publications covering th ose ar eas. The Br ief is divided into th ree sections. The first section deals with d efinitions, in which th e various activities relat ing to const ru ction a re clear ly defined. The activities are pr imarily drawn from ru ral road const ruction bu t can be 1

Tajgman, David, an d de Veen, J an . Employment-Intensive Infrastructure Program m es: Labour policies and practices. ILO, Geneva. 1998

2

Th e Labour-based T echn ology S ource Book: A catalogue of key publications.

ILO/ASIST, Nair obi. 1998

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applied t o many other labour-based activities su ch as th e pr ovision of wat er su pply, irr igation, dra ina ge or soil cons erva tion work. The definit ion of worker opera tions su ch as day-work, tas k-work an d piecework ar e also explained. The second section su mma rises th e productivity norms th at ha ve been r eported from man y projects in Africa an d Asia. These norms ar e related directly to the var ious a ctivities defined in t he pr evious section. A ra nge of ra tes is sh own, to demonstr at e the sort of variat ion t ha t can be expected un der differen t conditions. Recommen da tions a re a lso given for an avera ge productivity, which would be a rea listic an d achievable sta rtin g point for an y new pr oject or programme. Some activities draw up on m uch more data th an oth ers do; but wherever possible, anomalies are point ed out a nd commented on. The t hir d section gives guidan ce on t he factors t ha t can a ffect pr oductivity an d how productivity can be impr oved. It also gives advice on pr ocedur es for the sett ing, measu ring an d monitorin g of activities so th at project-specific norm s can be refined. For th ose who require more deta il, the pr oductivity data obtained in t his st udy is given by count ry an d activity in Annex 2. In a ddition, a sh ort hist orical sum ma ry of productivity in previous centu ries is pr ovided in Ann ex 3. This is intend ed to give a perspective on what can be achieved by workers when heavy equipment is simply not an option. This Brief is by its very na tu re a work in progress, an d ASIST will welcome comm ent s on it . Additiona l da ta will also be welcomed for in clus ion in fut ur e editions.


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2

Definitions for labour-based construction 2.1

T YPICAL ACTIVITIES All constr uction work can be broken down int o self-conta ined activities tha t can be a chieved by an ind ividua l or a gr oup of worker s if they ar e equipped with th e correct tools. The permu tat ions a re ma ny an d can of course be specified in t he most conven ient wa y for th e work in ha nd . However, to allow mean ingful compar ison between projects an d pr ogramm es, some sta nda rds h ave emerged which h ave been foun d to ha ve good universa l applicat ion. The th ree most common stan dar ds ar e those developed in th e Kenyan Ru ra l Access Road P rogram me (RARP) 3 ; th e par am eters specified in t he original World Bank stu dy into labour-based methods 4 ; a n d t h e p a r a m e t e r s p r op os e d in t h e ILO workplans ma nua l 5 bas ed on var ious pr ojects carr ied out in Fra ncophone mult i-sector projects . Such documen ts a s th ese, an d others quoted in the ASIST Source Book, should be cons ult ed by an y project designer requ iring det ailed solutions for sp ecific circum sta nces or “pre-cooked” solut ions r elatin g to say dam s, tree pla nt ing, paved roads etc.6 . However, for t his exer cise we ha ve concentr at ed on th e most common operat ions ut ilised in ru ra l road const ru ction. These activities will also const itut e th e ma jor a ctivities for a ny labour -based constr uction project an d as su ch will have th e biggest effect on costs a nd out put for most pr ojects . Based on th ese activities project plan ner s can evolve a rea listic set of activity norm s ta ilored t o th eir needs. Activit ies ar e ofte n combin ed int o one global activit y. A good examp le of th is is th e opera tion of ta king ma ter ial from a borr ow pit to form a n ear by emban km ent . In lar ge projects in Asia t his would comm only be described a s one a ctivity: excava te, load, h au l, unload (ELHU ). However, in Africa th is would be set as th ree discreet t asks, excavat ing to a st ockpile (E), loading into a wh eel barr ow (L), and ha uling t o the emban km ent (H) for u nloading (U). For th ese guidelines, all activities will be ta ken a s th e simplest const ituent par t. The pr incipal activities for t his exercise ar e defined below. As part of th e definit ion, a des cription is provided of th e sort of work to which th e activity applies; the t ools used; th e way 3

de Veen. Th e Ru ral Access R oads Programm e: Appropriate techn ology in Kenya. ILO, Geneva. 1993

4

Th e Stud y of Labour and Capital Su bstitution in Civil Engineering Construction, as summa rised in Coukis et al: Labor-based construction programmes: A practical guide for planning and management. The World

5

S tand ardised procedu res for the presentation of work plan s. ILO, Geneva.

6

September 1990 for example, Labour enha nced constru ction for bitum inous su rfacings: Methods and procedures. Souther n African Bitum en an d Tar Association. March 1993

Bank. 1983

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th e activity is measu red; and t he various par ameters t hat can be used t o subdivide the a ctivity even furt her. Even h an dtools can be defined different ly in different par ts of th e world. For t his t echn ical brief, all ha ndt ools are a s specified in th e Guide to Tools an d Equ ipmen t for Labour based Road Constr uction7 .

2.1.1

Site clearing This a ctivity covers th e rem oval of all obsta cles before serious excava tion commen ces. In road rela ted a ctivities it is often referred to as “clear ing th e road r eserve” or “bus h clear ing”. However, th e activity cert ain ly embra ces more obstacles th an just bu sh. As a general definition it includes th e removal of boulder s, buildings, tr ees, shru bs, gra sses, crops; and of topsoil cont ain ing an y vegeta ble mat ter which renders th e mat erial unsu itable for fill. The am ount of vegetat ive cover can differ considera bly, from semi-ar id ar eas wh ere t he clear ing work is negligible, to tr opical ra in forest s wher e chainsaws an d plant pu llers may (un fort un at ely) be necessar y to r emove extensive tr ee roots. Redundan t buildings ar e not common featu res on any ru ral project, although th ey may be in u rban upgrading programmes. For t his exercise it ha s been n ecessary t o make a subjective judgement on t he da ta received. Bush clearing h as been defined as light, medium or dense; to which ha s been a dded tr ee stum p rem oval (where individual tr un ks exceed 20cm in diameter), referred t o in Table 1 as de-stu mping, an d t opsoil removal 8 . For gen era l referen ce, definitions bas ed on th e type of tool necessary t o clear th e bush can be used t o identify bush dens ity (see Table 1 below). All clearin g is mea sur ed in squa re metr es except for su bstan tial trees an d boulders, which will require individua l task s to be set.

Table 1: Bush clearing characteristics Bu sh t yp e

S u i t a b l e t o o ls

Light bush

Bushknife, brush-hook

Mediu m bu sh

Scyt he, a xe, bowsa w

Den se bu sh

Axe, ch ain sa w, pla nt pu ller9

to tools and equipm ent for labour-based road constru ction. ILO, Geneva. 1982 8 Sometimes r eferr ed to as “grubbing”, although in ma intena nce opera tions th is typically only mean s rem oving plant r oots. 9 Any device for pulling directly from the ground by an imals, tr actors or ha nd opera ted winches, using pulling aids such as t ree hooks, mallet levers an d shea ve blocks. 7 Guid e


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2.1.2

Excavation This is th e most comm on labour -based a ctivity and can be applied to many items in a const ru ction pr ogramm e. Excavat ion is required: •

to produ ce a level road form at ion pla tform in virgin terrain

•

to obtain mat erial to raise or widen a road

•

for t he pr imary a ctivity in producing road side dr ains, even if th e side drain work ma y be broken down into first digging a tr ench and th en sloping the sides

•

in qua rr ies to obta in gra vel for sur facing

•

to form th e embank ment s of irrigat ion cana ls

•

to obtain m aterial for sma ll earth dams.

Even t he a ctivity of brea king u p rock boulders is str ictly speak ing excavat ion. This activity can usu ally be car ried out by h oe or shovel, but as t he ma terial har dens, a mat tock, pickaxe or even a h eavy crowbar 10 will be needed. For fra ctur ed rock, chisels a nd ha mm ers can be ut ilised, but for very ha rd rock, drilling and blast ing will be necessar y 11 . For soft m at erial, the worker will only r equir e one ha ndt ool such a s a h oe or shovel, but for ha rder m at erials each worker will need to be equipped with two tools, typically a pick to loosen t he m at erial, an d a sh ovel to rem ove it. The met hod of disposal of th e excava ted m at erial needs t o be well defined in how th e activity is sp ecified. Man y projects expect th e excavat or (th e person wh o does th e excavat ing) to load ma terial into a headba sket, wheelbarr ow or tr ailer as par t of th e operat ion. In oth er cases th e excavat or is expected t o “th row” th e ma terial out of th e road r eserve, or into th e cent re of th e road, to contribut e towards t he camber forma tion. A study of th e litera tu re an d coun try da ta received from var ious pr ojects confirms t ha t t his extr a operat ion does not seem t o add s ignifican tly to th e effort required. Thu s th e excavation para meter for t his stu dy is defined a s including loadin g or t hr owing, providing this does not in clud e a lift 12 of more th an one metre, or a t hr ow of more than four m etres. The most importan t par amet er for excavation is the har dness of the m at erial. This can alter th e expected pr oductivity by a factor of four or great er. Mat erials a re t ypically described as This item refers to an 11kg crowbar a t least 1.8 metr es long, with chisel and pointed ends, used a s an impact tool. 11 Fire an d water can be very effective but can be an environment ally dam aging operat ion as r ocky terr ain often occurs in ar eas with spar se vegetat ion an d a fragile environment . 12 “Lift” is a well described para meter in th e literat ur e referring to the h eight thr ough which ma terial mu st be m oved to be loaded or d isposed of. Labor10

based constru ction p rogram m es: A practical guide for plann ing an d management , page 284, Table F-3 and F igure F -3 detail the effects of

increased lift on pr oductivity.

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soft, medium, har d, very har d or r ock an d th ese terms a re us ed in th e compar ison of differen t pr oject da ta . The World Bank in th eir definitive study 13 produced a comprehensive definition based on soil type a nd tool penetr at ion. This is set out in Table 2 below in a simplified form a s a useful way for projects t o assess th eir individua l situat ion. As with th e site clear ing definition, the most pr actical descript ion is th e requ ired h an dtool, but t he soil descriptions ar e commonly accept ed ter ms for soil scient ists . All excava tion is mea su red in cubic met res of in situ material.

Table 2: Soil excavation characteristics Activity definition

Soil description Cohesive

Non-cohesive

Soft

Soft

Very loose

Ea sily excavat ed with a shovel or hoe

Medium

Firm

Loose

Can be dug with a shovel

Hard

Stiff

Compact

Mat tock, pick or other swung t ool required

Very har d

Very st iff or hard

Dense or very dense

Crowbar required in add ition to pick

Rock

Sledge hammer an d chisels required

Rock

2.1.3

Su ita ble tools

Hauling Ha uling is cost-effective when car ried out ma nu ally only for distan ces of up to 150 metr es. For grea ter distan ces, equipm ent becomes necessary. Typically, hea dloadin g is the most effective meth od up to 50 metr es, at wh ich point wheelbarrows ar e more suit able. However, it sh ould be n oted th at h eadloading is not comm on in Africa as a const ru ction operat ion, wher eas in some pa rt s of Asia, hea dloadin g is ut ilised for considera ble hau l distan ces (sometimes u p to a dista nce of 100 met res). Pr oductivity is very dependent on th e condition of th e ha ul route and th e height th rough which th e material must be moved, often r eferr ed t o as t he “lift”. Similarly, wher e wheelbarrows are u sed, the condition an d design of th e wheelbar row is crit ical 14 . Chinese wh eelbarr ows 15 ha ve a much higher capacity and pu t mu ch less strain on the worker , alth ough th ey do require some skill to balance. They 13

Op. Cit. page 282, Table F -1

ASIST ha s r ecently pu blished a Technical Brief which gives design a nd man ufactur ing details for a simple but r obust wheelbarrow suitable for use in labour-based constr uction works. See t he Reference section for deta ils. 15 A Chinese wheelbar row consists of a r ectangular tr ay, with sloping sides, mount ed on a lar ge-diamet er wheel positioned centra lly under th e tra y. For further details, see Guid e to tools and equipm ent, pages 7.26 and 7.27. 14


13

ar e not commonly available in Africa, but for projects with a considerable amoun t of wheelbarr ow ha ulage th ey may be w or t h t h e i n ve s t m e n t . Equ ipment ha ulage is typically car ried out by a tr actor/tra iler combinat ion for dist an ces up t o five kilometr es, with t ru cks being used t herea fter. However, this is a r ough guideline an d n eeds to be tested for individual circumst an ces. Lesotho uses only tru cks, wher eas Kenya uses t ractors an d tr ailers for qu ite long h auls, simply becau se th at is what t hey have readily available. The design of trailers is importa nt an d deta ils of a su itable type a re t o be found in ASIST Techn ical Br ief No. 1 16 . Most commercially available tra ilers ar e not su fficient ly robus t an d ar e too high for easy loadin g. Experien ce has sh own t ha t th e ideal capa city is 3m³. Similarly, tru cks should not be too large or t hey will be difficult to load a nd ma noeuvre on a labour-based site. Tipping tru cks with a capa city of 5 to 7m³ ha ve proved ideal. Equipment ha ulage productivity dat a was not acquired from projects by th is stu dy, but typical ha ulage inform at ion is included in t his n ote for completen ess (see Table 13). Table 3 presents t he h aulage ra nge an d capacity for t ypical equipmen t u sed on labour-based projects. All hau lage is mea su red in loose cubic metr es of ma ter ial for a specified hau lage ran ge.

Table 3: Haulage equipment characteristics Haulage equipment

Recommended h a u l i n g r a n g e (m )

Capacity

4 – 50

0.02m³

Western wheelbarrow

25 – 150

0.08m³

Chinese wheelbarrow

50 – 400

0.16m³

Animal car t

100 – 500

0.7m³

Tractor an d tra iler

250 – 5000

3 – 3.5m³

2000 upwar ds 18

5 – 6m³

Headbasket

Tipper truck

2.1.4

17

Loading, unloading and spreading As n oted in t he previous sections, th ese activities a re often combined with other s as a s ingle activity. Load ing is often par t of th e excavation activity where no double ha ndlin g of th e mat erial is involved, an d lifts a re less tha n one met re. Similarly loadin g, un loadin g and sp rea ding is often in clud ed 16

Ham per, J & Mason, D et al. Designs an d specifications for a stan dard trailer and h itch. Technical Br ief No 1. Third (r evised) edition. ILO/ASIST, N air obi.

1997 For t wo oxen or donkeys ha uling. 18 The dista nce at which t ipper tr ucks become more economic is very dependent upon site conditions an d the a vailability of equipmen t. This should be r esearched car efully before comm itting expensive procur ement or long term hire ar rangements. 17

14


with t he h au lage activity when mat erial is being obtained for a gr avel road s ur face from a st ockpile. However, it is importa nt t o ha ve dat a on the separa te activities so th at a pr oject can evolve its own n orms. L o a d i n g refers t o load ing from a pre-excava ted st ockp ile,

an d can be applied to any ma terial. However, it m ust be remembered t ha t if material is left t o stand for a considera ble period a nd subjected t o wett ing an d dr ying, it will need t o be re-loosened, which const itu tes a new excavation ta sk. Loading h eights of more t ha n one met re ar e very difficult by man ua l meth ods, an d loading ba ys should be fashioned to avoid th is problem. Loadin g is measu red in loose cubic metr es of ma ter ial. U n l o a d i n g is probably un ique to labour-based a ctivities in

civil engin eerin g. It d oes not refer to wheelbar rows or headba skets, but to emptying non-tipping tr ailers or t rucks. Becau se of ma ny pr oblems experien ced with sm all hydra ulically operat ed tipping t railers, man y projects ha ve found it pr eferable t o develop specially sha ped r igid t ra ilers which can be relat ively easily emptied by ha nd . The figur es given relat e main ly to 3m 3 tra ilers with or without special side doors. H owever, th ey are equ ally app licable t o flat tr ucks or larger tr ailers if th ey are properly designed. Un loadin g is mea su red in loose cubic metres of ma ter ial. S p r e a d i n g refers to th e genera l activity of conver tin g

loosely dum ped soil or gravel int o a sm ooth an d even road sur face. It in cludes m oving ma ter ial by shovel, hoe, rake, an d th e use of levelling devices such as th e cam ber board a nd str ing lines. Productivities a re s imilar for forma tion work, where th e mat erial is usua lly won from side drains; and gravelling, where th e ma terial is delivered by tr ailer or tr uck. No distinction is t herefore ma de in th is note between th ese operat ions. Sprea ding can be m easur ed in loose cubic metr es or squ are m etres of mat erial for a given th ickness. Table 4 lists th e typical ha nd tools used for t hese a ctivities.

Table 4: Tools for loading, unloading and spreading Activity

2.1.5

Su ita ble tools

Loading

Short or long han dled shovel

Unloading

Short or long han dled shovel

Spreading

Shovel, hoe, ra ke, sledgeham mers 19, cam ber board, string lines

Compaction It is n ot genera lly recommended to use m an ua l meth ods for compaction of road pa vements. Most r esearch a nd experience shows th at it is not possible to achieve enough impa ct t o ma ke an y significan t differen ce to th e density of th e 19

For brea king down oversize mat erial.


15

pavement ma terial. Compa ction should be car ried out either by towed or self-propelled equ ipmen t; or in some circumst an ces th e pavemen t can be left for t ra ffic to compact 20 . Manua l compaction can be u sed for backfill to drain age stru ctu res or in maint enan ce operat ions (such a s filling of poth oles), using h and r amm ers. Pavements a re best compacted with 1.25 tonne p edestrian opera ted vibrating rollers or t owed dead weight rollers with a weight of one t o two tonnes. Productivity r ates are given for both labour an d equipmen t operat ions. Man ua l compa ction is sp ecified in cubic metres of compa cted mat erial, and equ ipmen t compa ction in squa re m etres. When sp ecifying compa ction equipment it is importa nt to know th e da ily outpu t required. Most labour -based pr ojects produce a maximu m of 500 to 1000 squa re met res of forma tion or gravel pavement a day, and t he equipment should be mat ched t o tha t out put . Typical h eavy constru ction compaction equipment will ha ve much higher output s th an th is and will th erefore be largely un der-ut ilised. Conversely, sma ll-scale equipm ent can prove to be very unr eliable if worked eight h our s a d ay, day in day out. It is not designed for th is. Sta ndby equipmen t sh ould thu s be available, at least with a sufficient capacity to keep utilisation r at es down to four hours per da y. Table 5 specifies th e typical tools an d equipm ent us ed for compaction on labour-based projects.

Table 5: Tools and equipment for compaction Activity

2.1.6

Tool/equipment

Typical unit weight

Man ua l compaction

Rammer

7.5kg

Equipmen t compaction

Pedestrian operated vibratin g roller

1.25 tonn e


Towed dead weight roller

1.0 – 2.0 tonn e 21


Towed vibrating roller

600kg

Culvert laying Culvert laying is the most common dr ainage operat ion t hat can be specified a s a single a ctivity. More complex a ctivities su ch a s erecting ret ain ing walls, providing concret e drifts, or insta lling small bridges are best split d own int o their component par ts.

Bulletin No 3 , August 1994, gives an overview of resear ch on compaction altern atives. 21 A one tonne roller cann ot produce adequa te res ults with a ll soils, an d may need to compact in 75mm rat her tha n 150mm layers. A two tonne r oller is more reliable but t oo heavy for a nima l hau lage. 20 ASIST

16


Types of culvert can var y dram at ically from coun tr y to count ry a nd project to project. For t his exercise we ar e assuming that precast concrete pipes or galvanised st eel pipe sections (such as Armco) are alrea dy available on sit e an d th at th e opera tion cons ists of excava tion, providing bedding ma terial, laying and backfilling th e pipe segmen ts, an d providing upstr eam an d downstr eam hea dwalls. A typical set of tools for a culvert laying t eam is set out in Ta ble 6 below.

Table 6: Tools for culvert laying Typica l tools r e q u i r e d f or c u l v e r t l a y in g t e a m 22

2.2

Pick an d sh ovel for each worker, plus 5 crowbars, 5 wheelbarrows, 5 sledgehamm ers, 5 hand ra mmer s, boning rods, heavy rope.

WORK METHODS In a ll the literatu re on labour -based const ru ction t here is mu ch reference to daywork, t ask work an d piecework. Th ese ar e very str aightforwar d concepts, but un fort un ately they ar e sometimes d efined in d ifferen t wa ys by differen t pr ojects. This can give rise t o considera ble confus ion wh en compa rin g da ta from differen t pla ces. D a y w o r k mean s simply that a worker is paid a fixed rat e for

being presen t on a s ite for a full working da y, which is us ua lly eight h ours of work 23 . The a moun t of work produ ced depends entirely on th e su pervisor’s a bility to encour age th e worker , and th e worker ’s own motivation a nd sense of responsibility. In m an y circumst an ces th is can lead to very low productivity, especially with perm an ent sta ff who ha ve no par ticular incentive to work ha rd. They know th ey will be paid (generally very poorly) whet her th ey work or not. P i e c e w o r k is a m ethod of setting work, usu ally preferred by

th e private sector. The worker is allocat ed an amoun t of work for a n a greed rat e of pay. The work th ey do is measu red an d th e more th ey do th e more th ey are paid. This appr oach can give very high produ ctivities, but it can also resu lt in exploitat ion, especially when th e ra te for th e work is t oo low. Casu al workers a re seldom in a good position t o negotiat e favoura ble rates. The most dan gerous situat ion is wh en worker s h ave to put in very long h ours t o achieve even a su bsisten ce ra te of pay. T a s k w o r k evolved on pr ojects where th e work ers wer e

su bject to governm ent r egulat ions , which mean t th ey could not be paid more th an th e prevailing government wage for a da y’s work. Some oth er incent ive had t o be provided. Settin g All concrete an d mort ar can be effectively mixed by han d. However, wher e high quality concrete is importan t, man ually powered mixers ar e available. Conta ct ASIST for details. 23 In line with the r elevant Int ernat ional Labour Standa rds. See Tajgman & de Veen, Op. Cit., for a full explana tion of labour sta nda rds in r elation to labour-based works. 22


17

a r ealistic task , or a moun t of work to be completed for t he day, meant t ha t workers could work a s har d as th ey want ed an d th en go home to do oth er th ings. Tasks a re generally set to be achievable in 70 per cent of th e work ing day (a working day being assu med as a period of eight h ours), but ar e often complet ed in 50 per cent of th e work ing da y (i.e. in four hour s). This ap proach h as pr oved very successful in pra ctice, often doubling the am oun t of work a chieved in a da y; an d by inference doubling th e pr oductivity of the individua l worker, as well as ha lving th e costs. A variat ion of the individua l task is the g r ou p t a s k , wher e work is set for groups of people rat her th an for in dividua ls. This is done where the na tu re of th e work r equires th e coopera tion of a t eam, su ch a s excavat ing an d loadin g mat erial into tr ucks or t ra ilers. There is no basic difference in the concept, and t ask qu an tities are usua lly a simple mu ltiple of th e individual ta sks ma king up t he group. The most comm on mista ke is to confuse tas kwork with piecework , by sett ing more th an one ta sk in a day. If a pr oject is in t he situa tion where it can pay a variable rat e to the worker according t o out put , then th is should be considered as p iecework. Th ere is no problem with set ting work n orms based around th e recommen ded daily task, and t hen pa ying for m ore work on a pro rata basis. However, th e project m ust th en be set up t o accur ately measur e the am oun t of work completed, with th e agreement of the worker . In th is case th e procedur e should be clearly recognised an d ter med a s piecework . It is r ecommended th at if piecework is adopted th ere should be a clearly recognised minim um daily wage th at sh ould be paid if for some jus tifiable rea son th e work er’s out put is low (i.e. th e task was too har d). It should never be necessary t o work more tha n eight h ours in a day to achieve a ba sic daily wage.

18


3

Productivity norms To produce th is Brief, a questionna ire was circulat ed t o all active labour -based pr ojects in th e Sub-Sah ar an Africa region to obtain da ta on t heir curr ent n orms. In addition, a n umber of docum ent s were consu lted t o obtain dat a from completed pr ojects an d pr ojects in oth er regions. These sour ces of add itiona l inform at ion ar e included in Ann ex 1. The dat a was synt hesised to obtain a best fit with th e agreed par ameters an d is summ arised in Annex 2. The process was quit e problema tic since projects do not use t he sa me definit ions for activities, part icula rly with resp ect to th e difficult y of workin g in va rious soil conditions. H owever, average productivities ha ve been det ermined for a nu mber of count ries and a re set out below. From th is data, a median 24 value for ea ch a ctivity h as been calcula ted. To give this valu e a cont ext, we have included t he equivalent stan dard figure from th e Kenyan Rura l Access Road Pr ogra mm e. This pr ogra mm e was origina lly one of th e most resear ched pr ogramm es in th e region, an d gives a very good idea of wha t can be a chieved with t ight su pervision a nd a well motivat ed work force. When u sing productivity norms it is importan t t o appr eciate th at, although th ey can be the basis for setting ta sks, the amount actually achieved is often less th an the t ask set. This can be confirmed by post work m easu remen t. Sickn ess, bad weath er, an d u nexpected obstacles all cont ribute to reducing outpu t. Five count ries, na mely Botswa na , Gha na , Kenya, Lesotho and Zimbabwe, have recently condu cted sit e tria ls, measu ring actual output achieved over time, and t hese have also been synt hes ised to provide an idea of th e contin gency th at needs to be built int o any estimat ing exercise.

3.1

SITE CLEARING The figur es in Table 7 are compared with site t rials an d with th e origina l RARP d at a below (Table 8). The median figures for bus h clear ing an d grubbin g are very low compar ed to the origina l RARP figures an d th e measu red output from th e var ious t rials. In view of th is an d th e relat ive simplicity of th e activity, somewhat higher th an th e median figur es are recommen ded as a st art ing point. The informa tion on d estu mping is n ot sufficient t o make an y recommenda tions. Most pr ojects seem t o rely on th e experien ce of th e foremen to set appr opriate tas ks for t his activity.

The median value has been used rat her th an th e mean value, as the am ount of data was limited and t he m edian better excludes extreme or an omalous dat a. The mean is the sum of a nu mber of values divided by their n um ber. The media n is th e middle value of a series of values.

24


19

Table 7: Site clearing norms – country data Av e r a g e p r o d u c t i v it y b y t y p e o f co v e r m ² p er w o r k e r d a y Country

Dense bush

Medium bush

Light bush

Grubbing

Destumping

Botswana

—

750

750

150

Cambodia

30

60

100

15

Ghana

—

—

375

375

130

175

—

Kenya

50

150

300

100

—

Lesotho

50

100

250

65

—

Tanzania

50

100

250

150

Zimbabwe

200

—

300

250

—

WB Stu dy

—

—

150

15

—

Median

50

125

275

100

1

Indonesia

— 0.75 —

37.5

1

3.5

Table 8: Site clearing norms – recommended values Av e r a g e p r o d u c t i v it y b y t y p e o f c ov e r m ² p er w o r k e r d a y Dense Medium Light Grubbing De-stumping bush bush bush

Count ry median

3.2

50

125

275

100

1

Site trials

105

209

311

209

—

RARP

320

480

640

I75

—

Recommended va lu e

100

200

350

175

By experience

EXCAVATION The h ighest productivity n orms for excavat ion were in Ch ina with pr oductivity rates u p to 9 an d 7m³ per da y respectively for soils classified a s of soft or m edium worka bility. However, China is very well orga nised in t his sort of activity, an d its worker s ar e accust omed t o work levels which ma y not be accepta ble in other regions of th e world. Zimbabwe’s pr oductivity norms were up to 6m³ per da y an d consistently higher t ha n oth er coun tries in a ll activities. Materials in Zimbabwe are not n oticeably easier t han oth er centr al an d east African coun ties. It is interest ing to note th at th e data ar e from a relat ively new project u nder close supervision a nd m onitoring. Having said t ha t, worker s were achieving th eir task s in 70 t o 80 per cent of th e normal day, so these levels should be gener ally achievable. Some of the r ock excavation figur es ar e high a nd ma y reflect a lack of data in th is area for ma nu al meth ods, apart from Lesoth o and N epal.

20


Table 9: Excavation norms – country data Country

Av e r a g e p r o d u c t i v i t y b y s o i l c l a s s i fi c a t i o n m ³ p er w o r k e r d a y Soft

Medium

Hard

Very hard

Rock

Botswana

4.15

3.8

2.5

1.9

—

Cambodia

2.75

2

1.25

0.75

—

China

9

7.0

3

2

—

Ghana

3.75

3.75

3.75

3.75

—

Indonesia

—

—

2.5

—

—

Kenya

5

3.5

2.25

1.75

0.75

Lesotho

4.5

3.5

2.75

1

0.5

3.3

2.5

—

0.61

Nepal

—

Tanzania

5.5

4.5

4

2.5

—

Zimbabwe

5.5

5.5

4

3.5

2

WB Stu dy

6.7

2.1

3

2

1.7

Median

5.00

3.50

2.75

2.00

0.75

The median results can be compa red with t he resu lts from recent trials a nd t he original productivity norms from t he RARP. It is noticeable that th e data from the var ious t rials for soft, medium an d ha rd soils is very scat ter ed, with impr obably high figures for very h ar d soil. This probably reflects a lack of at ten tion to site conditions am ong site supervisors. In general, the norms being set by projects do not differ significan tly from t hose origina lly developed in Kenya.

Table 10: Excavation norms – recommended values Av e r a g e p r o d u c t i v i t y b y s o i l c l a s s i fi c a t i o n m 3 per worker day Soft

Medium

Hard

Very hard

Rock

Count ry median

5.00

3.50

2.75

2.00

0.75

Site trials

3.6

3.2

3.45

2.2

0.8

RARP

5.5

4

3

2

Recommended va lu e

5 .0

3.5

3.0

2.0


— 0.8

21

3.3

HAULAGE Productivity rat es for wheelbarr ow ha ulage appear to have declined considera bly since th e inception of th e RARP programm e. Some r oad projects no longer use t his a pproach as t hey cons ider it ineffective, relying on adjacent m at erials for all fill requiremen ts. However, man y other infrast ru ctu re projects , par ticular ly soil an d wat er cons erva tion projects an d ur ban projects, will ma ke mu ch m ore use of th is activity.

Table 11: Wheelbarrow haulage norms – country data W h e e l b a r r o w 25 h a u l a ge n o r m s b y h a u l d i s t a n c e m 3 per worker day

Country

0-20m

20-40m

40-60m

60-80m

80-100m

100150m

8.4

7

6.7

5.6

5.2

4.7

10.5

10.5

8

6.5

5.5

4.5

8

6

5

4.5

4

11

11

8.25

6.25

5.25

5

Zimbabwe

5

5

5

5

5

4

Median

8.4

7

6.7

5.6

5.2

4.6

Botswana Kenya Lesotho Tanzania

—

It h as t her efore been decided to keep the r ecommended norms at th e higher end of th e ran ge. These figur es are achievable but require t he operat ion t o be well set up , part icularly with r egard t o the condition of th e ha ulage route. World Ban k dat a 26 h a s d e m on s t r a t e d t h a t a p oor h a u l route can halve productivity.

Table 12: Wheelbarrow haulage norms – recommended values Wh e e l b a r r o w h a u l a g e n o r m s b y h a u l d i s t a n c e m ³ p er w o r k e r d a y 0-20m

20-40m

Count ry median

8.4

7.0

6.7

5.6

5.2

4.6

Site trials

5.3

4.8

4.6

4.3

4.2

4.1

13.5

10.5

8.5

6.5

5.5

8.5

7.0

6 .5

5.5

5.0

RARP Recommended va lu e

40-60m 60-80m 80-100m

100150m

— 4.5

Equipmen t h au lage productivity depends t o a large extent on th e efficiency of th e loadin g tea ms. H owever, ha ula ge route condition a nd t ype of ha ulage equipm ent also play a lar ge part , as well as t he organisation of the loading an d un loading areas. This r efers to a typical wester n wh eelbar row in good condition. Chinese wheelbarrows could a chieve significant ly higher r at es. 26 Coukis et al 1983. Op. Cit. 25

22


To aid the designer, a ta ble has been provided giving th e nu mber of trips t ha t can be expected from either a sm all tipping t ru ck, or from a tr actor-plus-two-tr ailers combina tion, in a da y. Qua nt ities have not been included her e since th is will depend on th e capa city of the tr uck (typically 5m 3 of loose mat erial) or t he t ra iler (typically 3m 3 of loose ma te ria l).

Table 13: Typical haulage rates for manually loaded equipment Hau l r oute condition

Hau l distan ce (km)

3.4

Good

2

4

6

Average

8 10

2

4

6

P oor

8 10

2

4

6

8 10

Trips per day per truck 27

22 19 16 11

8 18 15 12

8

6 16 12 10

7

5

Trips per day per tractor/trailer combination28

20 12

4 18 11

5

4 16

4

3

8

6

6

9

4

LOADING, UNLOADING AND SPREADING The median norms do not differ ma rkedly from th ose set by th e origina l RARP pr ogram me, although t he t rials show slight ly lower pr oductivities being a chieved for loading a nd spread ing. If hydra ulic tipping tra ilers or tr ucks ar e used, th en th e man ua l unloading activity is not required. Table 14: Loading, unloading and spreading norms – country data Country

Av e r a g e p r o d u c t i v i t y r a t e s m ³ Loading

Unloading

Botswana

12

Cambodia

8

15.5

Ghana

6.7

10

Kenya Lesotho Tanzania Zimbabwe World Ban k Median

—

Spreading

14 5.25 —

10

9

13.5

5

—

14.25

11

—

15

—

9

—

11

10

13.5

8.5 — 8.5

Modified from th e LCU Techn ical Manu al , Ministr y of Works, Kingdom of Lesotho, May 1996. 28 Modified from th e MRP Techn ical Manu al , Ministr y of Public Works, Republic of Kenya, J an uar y 1992. 27


23

Table 15: Loading, unloading and spreading norms – recommended values Av e r a g e p r o d u c t i vi t y r a t e s m³ per worker da y Loading

3.5

Unloading

Spreading29

Count ry median

8.5

10

13.5

Site Trials

6.5

11

12

RARP

8.5

—

13.5

Recommended va lu e

8.5

10

13.5

COMPACTION No significan t additiona l dat a was obtained from t he t rials on ma nu al or equipmen t compa ction. In a ddition, a RARP compa rison cann ot be m ade a s th ey did n ot u se ta sks for compaction bu t lar gely relied on tr affic consolidat ion of th e pavement . Hence, for t his st udy, the m edian r esults below are t he recommen ded values. These values ar e in line with th e expected values from th e litera tu re.

Table 16: Compaction norms – country data and recommended values Country

Cambodia

Manual compaction

Equipment compaction

m 3 per worker day

m 2 per roller day

10

—

China

3.2

—

Kenya

7.5

700

Lesotho

15

700

Tanzania

9

700

Median

9.0

700

R e c om m e n d e d v a l u e

9.0

700

As noted in th e section on compa ction a bove, ma nu al comp action is only recomm end ed for backfilling or oth er min or operat ions . It is n ot effective for consolidat ing pavemen ts. In addit ion, the ma chin e figures should be cha nged if differen t t ypes of equipm ent ar e used. Hea vier items of vibratory equipment will need fewer pas ses, and th e reader is referred t o Table F8 of th e World Ban k Labourbased Constr uction Pr ogra ms Guide or TRL guidelines for typical construction equipment output. Conversely, lighter towed a nd non-vibratory items m ay need m ore pa sses or Sprea ding activities ar e often specified in squa re met res, par ticularly if th e activity is spr eading ma ter ial excavat ed from side ditches to form a camber . If this meas ur e is preferr ed, simply divide the norm by the avera ge th ickness . Thus a typical average thickness of 0.15 met res gives a spr eading norm of 90m 2 per worker day.

29

24


th inner layers of mat erial between passes, an d th ese must be tested against th e individua l equipment item. Existing performa nce data for su ch equipment is not very reliable since ther e ha ve been very few published exam ples of rigorous scient ific tes tin g30 . Most light equipment has cons ist ed of locally fabr icate d one-off devices, us ed in circum st an ces wher e soils tes tin g facilities wher e not available.

3.6

CULVERT LAYING The RARP did not h ave a linear metr e rat e for culvert laying or a specific ra te for concret e an d ma sonry work, but a few recent trials h ave been carried out on th ese norm s in Kenya, Lesoth o and Zimbabwe, showing significan tly lower r at es being achieved for concrete an d ma sonr y work . However, based on other r eading, it is recomm ended t o keep th ese ra tes n ear t o th e specified norms .

Table 17: Culvert laying norms – country data Country

Activity Culvert installation m per worker day

Cambodia

—

Concrete m ³ per worker day

1.25

Masonry m ³ per worker day

1.25

China

1.2

—

—

Kenya

0.3

1

1.5

Lesotho

1.1

1.75

1.35

Zimbabwe

0.8

0.8

0.75

Median

0.9

1.13

1.3

Table 18: Culvert laying norms – recommended values Country

Activity Culvert installation m per worker day

3.7

Concrete m ³ per worker day

Masonry m ³ per worker d ay

Count ry median

0.9

1.13

1.3

Site trials

0.95

0.6

0.6

Recommended va lu e

0.9

1.0

1 .0

AN EXAMPLE OF COMBINED ACTIVITIES Using th e above activity norms , the engineer can combine activities to span an overall operat ion a nd derive suitable combin at ions of work ers a nd equipm ent . A typical example of a gra velling operat ion is given below. This is based on t he us e of 60hp t ra ctors in two-tr ailer-to-one-tr actor 30 ASIS T

Bu lletin No 3 , Augus t 1994, gives an overview of res ear ch on light compaction equipment.


25

combinat ions on an a verage quality of ha ul route an d with workers fun ctioning on t he t ask rat e system, excavating in h a r d m a t e r i a l. The examp le is actu ally from th e Kenyan MRP Techn ical Manu al, which has a nu mber of useful tables for estimat ing equipment an d labour r equirements based on over twenty year s of experien ce. Table 19: Typical equipment /labour combinations for gravelling Haul Loads Total Excavation distance per vo lu m e day

3.8

Loading

Workers per Workers tractor per tractor

Un Spreading loading

Km

unit

Loose m3

Workers Workers per per tractor tractor

0 to 2

18

54

18

7

6

4

2 to 4

11

33

11

4

4

2

4 to 6

7

21

7

3

2

2

6 to 8

5

15

5

2

2

1

8 to 10

4

12

4

2

1

1

SUMMARIES The set of tables below sum mar ises the recommended values for th e various a ctivities.

Table 20: Summary of recommended values SITE CLEARING Av e r a g e p r o d u c t i v it y b y t y p e o f c ov e r m ² p er w o r k e r d a y Dense Medium bush bush

Recommended va lu e

100

200

Light Grubbing De-stumping bush

350

175

By experience

EXCAVATION Av e r a g e p r o d u c t i v i t y b y s o i l c l a s s i fi c a t i o n m 3 per worker day

Recommended va lu e

Soft

Medium

Hard

Very hard

Rock

5.0

3.5

3.0

2.0

0.8

WHEELBARROW HAULAGE Wh e e l b a r r o w h a u l a g e n o r m s b y h a u l d i s t a n c e m ³ p er w o r k e r d a y 0-20m

26

20-40m

40-60m 60-80m 80-100m

100150m


Recommended va lu e

8.5

7.0


6.5

5.5

5.0

4.5

27

LOADING, UNLOADING AND SPREADING Av e r a g e p r o d u c t i vi t y r a t e s m³ per worker d ay Loading

Unloading

Spreading

8.5

10

13.5

Recommended va lu e

COMPACTION Manual compaction

Equipment compaction

m 3 per worker day

m 2 per roller day

9.0

700

Culvert in sta llation

Concrete

Recommended va lu e

CULVERT LAYING Masonry

m per worker m ³ per worker m ³ per worker day day day

Recommended va lu e

0.9

1.0

1.0

TYPICAL HAULAGE RATES FOR MANUALLY LOADED EQUIPMENT Hau l r oute condition

Good

Haul distance (km)

2

4

6

Av e r a g e

8 10

2

4

6

P oor

8 10

2

4

6

8 10

Trips per day per truck

22 19 16 11

8 18 15 12

8

6 16 12 10

7

5

Trips per day per tractor/trailer combination

20 12

4 18 11

5

4 16

4

3

8

6

6

9

4

TYPICAL EQUIPMENT / LABOUR COMBINATIONS FOR GRAVELLING Haul Loads d i s t a n c e p er day Km

28

Total vo lu m e

unit Loose m 3

Excavation

Loading

Workers per Workers tractor per tractor

Un Spreading loading Workers Workers per per tractor tractor

0 to 2

18

54

18

7

6

4

2 to 4

11

33

11

4

4

2

4 to 6

7

21

7

3

2

2

6 to 8

5

15

5

2

2

1

8 to 10

4

12

4

2

1

1


4

Factors affecting productivity The preceding sections h ave set out t he a verage amount of work th at can be expected from a n a verage worker in reasonable health, based on observed data from ma ny projects a nd count ries. However, th is avera ge figure can be affected by ma ny factors, which a re fort un at ely mostly un der th e cont rol of the programme m an agement. The most i m p or t a n t a r e : •

Motivat ion a nd experien ce of th e work force

•

Organisat ion of the work

•

Type and condition of tools an d equipm ent provided t o t h e w or k e r

•

Contin ua l monit oring of perform an ce.

These factors ar e discussed in t he following sections .

4.1

M OTIVATION AND EXPERIENCE OF THE WORKFORCE The World Bank in t heir seminal stu dy3 1 produced various ta bles at tempt ing to sum mar ise the observed differences in productivity between pr ojects a nd p rogra mmes t akin g into account th e fam iliar ity of th e count ry with labour -based meth ods (i.e. organisation an d worker experience) and t he meth od of payment of th e worker s ( i.e. motivation). The exam ple below uses excavat ion of mediu m h ar dnes s soil as t he baseline ( i.e. with a norm of 3.5m³ per work er da y).

Table 21: Observations on worker output 32 P aymen t method

Count ries’ exper ience with labour-based technology New ap proach m ³ per day

Long tradition m ³ per day

Daily paid

0.88 to 2.62

1.75 to 5.25

Taskwork

1.75 to 5.25

3.5 to 8.75

Piecework

3.5 to 10.5

7.0 to 14.0

The m ost st rikin g feat ur e is th e differen ce by a factor of 16 between inexperienced an d presu ma bly poorly paid day worker s, and experienced piece worker s. In m itigation it h as to be said th at new workers often find th is type of work quite difficult for th e first two weeks, alth ough t hey qu ickly develop the required m uscles. Thus t ask worker s should qu ickly move to the m edian figur e of 3.5m³. Daily paid workers seldom h ave th e motivation t o improve, an d th e Coukis et a l, 1983. Op. Cit. This ta ble is ta ken directly from th e World Ban k Stu dy, Coukis et a l, 1983. Op. Cit., page 180, Ta ble 7-7.

31 32


29

au th or has observed productivities increa se by a factor of four, simply by int roducing task work m eth ods to an experienced da ily paid labour gan g. Conver sely, piece worker s ten d to work very long h ours indeed if the m oney is ava ilable. Twelve to 14 hours were not u ncomm only observed occurr ences on su b-cont ra cts in th e Indian s ub-continen t. Although p iecework demonstra bly gives th e highest out put , it does ha ve its own problems a s discussed in section 2.2. On a well-organ ised an d contr olled const ru ction sit e with easily measur able quant ities, there are real advan ta ges for all involved, par ticular ly if th e workforce is living in a constr uction cam p awa y from home, with th e sole motivat ion being maximum ear nings in a min imum t ime. However, in th e more t ypical ru ral works, dra wing on local labour with oth er h ome-based int erests (par ticular ly subsistence agricultur e an d family care), ta skwork h as proved a mu ch more viable option. However, for ta skwork t o fun ction corr ectly it is essentia l to esta blish th e correct daily wage. If th e wage is much lower th an th e prevailing cash wage for similar work in th e area th en th ere is a danger th at a n insu fficient nu mber of workers will be attr acted, an d th e att endan ce of those th at do come will be un reliable. If th ere is very high u nem ployment , or more comm only if th ere a re few alt ern at ive cha nces of getting waged employment (as opposed t o payment in kin d), it ha s been found th at , although worker s will be recru ited, th ey will lack motivat ion a nd be resen tful of norm al ta sk rates. Responsible man agement m ust avoid the situa tion where below-povert y-line-paym ent s a re bein g accepted by desperat e people. Conversely it is import an t t ha t wages are not so high a s t o distort th e local economy. Labour -based projects seldom creat e perma nen t em ployment, an d if workers are t empted a way from existing full time employment in essential a gricultu ra l or service area s, then th e local economy m ay su ffer. It is usu al pra ctice to carr y out a t horough labour m ark et ana lysis in any n ew area wh ere labour-based programm es are being st art ed. This should establish th e basic acceptable wage, and most import an tly the inflation index whereby an nu al increments can be determined 3 3 . One problem facing the site man ager is th at , because a work force does improve with experience, th ere is t he tempt at ion t o car ry th e workforce forward for t he du ra tion of th e project. The n ormal pr actice is to recru it workers adjacent to the works an d let worker s go as t he work progresses. This has th e benefit of spreading ear nings an d skill acquisition th rough t he served commu nity. On th e oth er ha nd, keeping on workers can result in t he establishment of 33

There h ave been several documen ted cases where, alt hough thoroughly resea rched wage levels have been established a t th e star t of a pilot project, wage levels have then been kept at tha t level for m any year s in count ries experiencing high inflation. In all cases the pr oblem ha s been th e lack of an accepted mechanism for wage adjustment .

30


labour camps an d the disruption to ru ral settlements th rough t he influx of a r elatively lar ge num ber of cash rich migrant s. On balan ce it is recommen ded tha t th e unsk illed labour force is d iscoura ged from following t he project, a nd cam ps an d tr an sport should not be provided un less there is insufficient population in t he ar ea. On the other h an d, individua ls with special skills can be ta ken on as supervisors, art isans, or fut ur e maintena nce workers. If a commu nity ha s su fficient vested interest in th e works being car ried out becau se of th eir direct benefit, th en it is possible tha t worker motivat ion will be much higher. However, it is difficult to program me for t his, an d an y such pr oductivity boost sh ould best be considered a s a bonus ra th er th an as a factor to be built int o th e expected ta sk ra tes. Convers ely, if a work force is in ver y poor p hysical condition becau se of maln ut rition, it is inappr opriat e to expect n orma l out pu t. Any project opera tin g in conditions of fam ine or extr eme poverty sh ould alter its n orms accordingly.

4.2

ORGANISATION OF THE WORK This factor relies entirely on th e tr aining a nd experience of th e site supervisory sta ff, and its importan ce cannot be un derest imat ed. The labour force will in fact qu ickly learn wha t is expected of th em an d in our general experience will th en work well and skilfully. However, th e initial direction can only be given by th e sup ervisors. Ha ving said t ha t, it ha s to be recognised th at labour-based technology is very su pervisor intensive, and without t he continu ed pr esence of train ed su pervision, outpu ts will drop substa ntially. Table 13 sets out t he variat ion in ha ulage times for m at erial depending on t he qua lity of th e ha ulage route. This is not entirely a measu re of th e roughness of th e route, but of th e set-up of th e quar ry an d th e site unloading opera tion. These factors are lar gely dependent on th e organisa tion of th e work . Similarly, the qu ality of work will also decline if th e level of su per vision is r edu ced. Training ma terials ha ve been developed by a n umber of pr ojects which give det ailed s pecificat ions for a ll activities, how to organ ise the work, worker balan ce between th e var ious crit ical a ctivities etc . These training ma terials can only be effectively applied in conjun ction wit h a tr ain ing site, an d t his pr ocess of super visor tr aining is a prerequ isite for an y large-scale operat ion. A listin g of suita ble published tr ainin g mat erials can be obta ined from ASIST. Tra ining cour ses covering th e man agemen t of labour-based road works ar e also provided by the Kisii Training Centr e 34 in Kenya.

Contact t he P rincipal of KIHABT, PO Box 57511, Nairobi, Kenya (Fax +254-2-534890) for t he lat est course det ails.

34


31

4.3

T OOLS AND EQUIPMENT SPECIFICATION AND MAINTENANCE Unfort un at ely, there is n o precise data on t he exact ma gnitu de of th e effect on pr oductivity of ha ving poor qu ality tools. Recent st ud ies 35 indicate t ha t blun t or worn excavating tools can redu ce worker outpu t by up to 25 per cent . Badly ma de or poorly fitt ed ha ndles a lso ha ve a significan t n egative effect, but th is was n ot measu red qu an tita tively. However, th e actua l effects of th ese factors on outpu ts in a project a re disguised by the taskwork system. Stan dard n orms a re esta blished with good qua lity tools at t he st ar t of a pr oject. As t ool qua lity decreases, the worker s h ave to compensa te by put ting in longer hours t o achieve their daily task . This is not fair on t he work force, nor is it r ealist ic for long-ter m p roject effectiveness . The overall effect for th e pr oject is a gra dua l lowering of morale an d a decline in sta nda rds a s th e task s become hard er. The bottom line is t ha t if a t ool ha ndle is broken or th e point of a pick is fractured t hen th e worker using it can not pr oduce th e required amount of work for t he day in th e time ava ilable. The work er is effectively on down tim e, as with an y item of broken powered equipmen t. As a genera l rule, poor t ools can redu ce individua l worker outpu t in th e long run by a least a half. Tool man agement m ust achieve two th ings to ensu re ma ximum pr oductivity. First ly a h an dt ool of th e correct str ength for th e rigour s of const ru ction work mu st be specified and procur ed so th at it does not eas ily break or bend on th e job. Secondly a system of rout ine ma inten an ce an d tool replacement mu st be in place on any site to ensur e th at workers always ha ve good t ools. The s pecificat ion of tools is covered in a nu mber of pu blicat ions , the definitive work bein g th e ILO Guide t o Tools an d E quipment 36 . As th is guide shows, agricultur al tools are not a ppropriate for m an y roadwork activities, and it ma y be necessary to get local ma nu factu res to cha nge th eir specificat ions. Th is can be a n expen sive option for a sma ll tool ru n so it is often n ecessa ry to import from abr oad. An alt ern at ive is to encoura ge small-scale specialist pr oduction using scrap met als from cars or other indust rial uses. For cast items it is relatively easy for a man ufactur er to cha nge th e composition of th e met al, but r etooling for a n ew sha pe is mu ch more expensive. Maint ena nce of tools will requ ire an on-site work sh op which can replace ha ndles, shar pen edges of cut ting t ools, and reforge picks, chisels an d crowbars . The a ltern at ive is th at IT Transport Ltd. Effects of worn ha nd tools on worker productivity in labourbased roadworks. MART Workin g Pa per N o 9. Institu te of Development En gineering, Loughborough. 1997. Pau l Larcher. MAR T qu estionn aire on tools and equipment . Pr oceedings of the 6 th Regiona l Seminar for Labour -based

35

Pr actitioners. CTP 157. ILO, Geneva. 1998 36

Guid e to tools and equipm ent for labour-based constru ction. ILO, Geneva.

1981

32


tools are r egularly replaced on-site a nd sent for remedial ma inten an ce to a centr al depot. The worse situa tion is where tool ma int ena nce is left t o th e discret ion of individua l users . This can lead t o the fitt ing of “bus h” han dles, poorly secur ed axe and pick heads, and other h orrors th at can easily result in severe accidents a s well as poor outp ut .

4.4

M ONITORING NORMS Once norms ar e established, it is normal pr actice to build th ese into the da ily site reporting pr ocedur es an d to rely on th e supervisor t o set a nd check t he ta sks daily. It h as t o be appr eciated however t ha t, over time, super visors can become blasé about mak ing detailed measu rement s, and often fail to check t he finished quan tity against t he assigned task . The pegged dista nces are invar iably achieved, but th e physical quan tities thereby assumed by the supervisor ma y not equal th e theoretical norm. It is therefore essential th at m ore senior ma na gement sta ff periodically check th ese productivity settin gs. This mean s physically checking th e site measurement s, not just t he data sh eets. In a ddition, it is often th e pra ctice of mana gers to tak e th e reported da ily task s set for t he var ious a ctivities, and to assu me tha t th ese represent t he actua l out put of th e project. This ha bit ha s grown with force account operat ions where paymen t is not linked to production, but to worker mu ster rolls. In fact, quan tities ar e seldom equa l to the sum of th e set p rodu ctivities. Site obsta cles, diversion of worker s to other a ctivities, sickn ess, broken tools, wrong ta sk set tin g, all contr ibut e to a false total. It is n ot being suggested th at all finished work should be remeasu red. This would probably put t oo great a bu rden on t he typically small su pervision tea m of a labour -based project. At th e end of th e day, what is required is a usa ble piece of infra st ru ctur e at a cost -effective pr ice. It is ther efore suggested th at work pr ogress should be tr acked in t erms of certa in key out put s. In th e case of roads th is is usu ally kilometr es of form at ion completed, kilometr es of gra vel placed, an d linear m etr es of culvert s placed. As long as t hese figures ar e accur at ely recorded on site t ogether with t he nu mber of worker da ys expended t o achieve th is, a good measu re of site progress an d cost will be obtain ed. Some typical inpu ts from various pr ojects a re listed in Table 22. These ar e based on recent evaluations a nd a re calcula ted from tota l work er inp ut s to complete specified roads . As su ch t hey cap tu re all activities including th ose not specified or set as t asks . Mont hly reportin g of such t otals from site give man agemen t an excellent t ool for monitorin g progress an d problems. Ea ch project a nd program me sh ould esta blish its average input for key operat ions a s a first priority, an d check t his against site r e t u r n s e v er y m o n t h .


33

Table 22: Average worker input for completed operations P r o je c t

Op er a t ion

In p u t

Con stru ction of

w ork er d a ys/ k m

Botswana 37

Earth road

1981

Botswana 37

Gravel topping only

2157

Ghana DFR38

Gravel lowland road

1580

Kenya MRP 39

Earth lowland road

1442

Kenya MRP 39

Gravel topping only

1819

Kenya MRP 39

Regravelling

1209

Laos LAO/90/MO1/FRG40

Gravel lowland road

2203

Lesotho LCU 41

Gravel lowland road

2645

Lesotho LCU 41

Gravel mountain road

4400

Zimba bwe LBDU 41

Gravel lowland road

3260

See Brudefors, Ulf; Keam, Dave; Strøm, Ørnulf. LG-117 labour intensive public works labour-based road program m e. Review of techn ical status.

37

Ministry of Local Governm ent, Lan ds an d Housing, Botswan a. 1995 Tuffour, AY; Ampa du , KS. A study of the field performance of selected labourbased contractors in Ghan a. In: Proceedin gs of the Fifth R egional S emin ar for labour-based pra ctitioners, 22n d – 2 7 th April, 1996 Accra, Ghan a. August 1995

38

39 Annual

R eport for the Road Sector. Ju ly 1996 – Ju ne 1997 & J uly 1997 – Ju ne 1998. Ministry of Public Works an d Housing, Nair obi, Kenya.

November 1998 Due Langaa s, Marit. Laos labour-based ru ral road construction a nd maintenance. Internal evaluation . ILO, Geneva. 1996 41Lennar tsson, Maria & Stiedl, David. Techn ology choice: Man or Machin e. ILO/ASIST. 1995 40

34


ANNEX 1: References Note: T he reference nu m bers refer to the citation s in AS IS TDOC, the bibliographic database of AS IS T, w hich is ava ilable from th e Ha rare or N airobi offices, or from th e AS IST website.

GENERAL Gu ide to tools and equipm ent for labour-based road construction. ILO, Geneva . 1981. Ref. No. 00162

Ham per, J & Mason, D et al. Designs an d specifications for a stan dard trailer and hitch for labour-based w orks. Technical Brief No. 1. Thir d (revised) edition. ILO/ASIST N air obi, Kenya . 1997. Ref. No. 02334 Heavy du ty wh eelbarrow for labour-based infrastru cture works. An illustrated step-by-step guide to its construction.

ILO/ASIST, N air obi. 1997. Ref. No. 09557 Heavy dut y wh eelbarrow. Jigs an d fixtu res for batch production. ILO/ASIST, N air obi. 1997. Ref. No. 09570

IT Tran sport Ltd. Effects of worn han dt ools on worker produ ctivity in labour-based roadw orks. MART Working Pa per N o. 9. Lough borough U niver sity of Techn ology. 1997. Ref. No. 02381 Labour enh anced construction for bitum inous surfacings.

Man ua l 11. SABITA. 1993. Ref. No. 01591 Larcher, P. MART questionn aire on t ools and equipm ent. In : Pr oceedings of th e 6 t h Regional Semina r for La bour -based Pr actitioner s. ILO, Geneva. 1998. Ref. No. 02400 Scott Wilson Kirkpat rick & P art ners; Brian Woodhead & Co. Labour Construction Un it: Techn ical Manu al. Ministr y of Works , Lesoth o. 1983. Ref. No. 01000 S tan dard ised procedu res for the present ation of work plan s.

ILO, Geneva . 1990. Ref. No. 03658 Tajgman , D & de Veen, J . Em ploym ent intensive infra structu re program m es: Labour p olicies and practices.

ILO, Geneva . 1998. Ref. No. 14111 T he La bour-Based T echn ology S ource Book. A catalogue of key publications. Fourth (revised) edit ion. ILO/ASIST, Nairobi.

1998. Ref. No. 07143

USED FOR PRODUCTIVITY RATES Annu al R eport for the Road S ector. J uly 1996 – Ju ne 1997 & Ju ly 1997 – J un e 1998. Ministr y of Public Work s an d

Hous ing, Na irobi, Kenya . November 1998. Ref. No. 27686 Bentall, PH . Gha na feeder roads project labour-based rehabilitat ion an d m aint enance. Final report. ILO, Geneva. 1990. Ref. No. 26023


35

Bru defors, U. LG-34 Labour Intensive Road program m e. Final R eport. ILO, Geneva . 1991. Ref. No. 22101 Bru defors, Ulf; Keam, Dave; Strøm, Ørn ulf. LG-117 labour intensive pu blic works la bour-based road program m e. R eview of techn ical status. Ministry of Local Governm ent , Lands a nd

Housin g, Bots wan a. 1995. Ref. No. 22066 Contract conditions and specifications. Labour-based

Developmen t Un it, Depart men t of Roads, Zimbabwe. 1995. Costa et al. Gui delin es for the organi sation of special labourintensive works program m e. ILO, Gene va. Ref. No. 01637 Couk is et a l. La bour-based Const ruction Program s: A practical guide for planning and management. World Ban k. 1983. Ref. No. 00249 De Veen, J J . T he Ru ral Access R oad Program m e. Appropriate techn ology in Kenya. ILO, Geneva . 1993. Ref. No. 01245 Due Lan gaas, M. La os labour-based rura l road constru ction and m aintenance. Internal E valuation. ILO, Geneva. 1996. Ref. No. 43087 En gdahl, A. In troduction to labour-int ensive m ethods of road constru ction and m aintenan ce: Produ ctivity of labour.

Minist ry of Local Govern men t, Botswa na . 1988. Ref. No. 22087 Int ech Associat es. Min or Roads Program m e Technical Manual V olum e I. Minist ry of Pu blic Work s, Kenya . 1992. Ref. No. 27298 Int ech Associat es. Roads 2000 Works Man ual. Ministr y of Pu blic Works , Kenya . 1996. Ref. No. 27448 IT Tran sport. Techn ical man ual for low volum e roads upgraded an d constru cted u sing labour-based m ethods in Lesotho. Minist ry of Work s, Lesoth o. 1996. Ref. No. 28141

Karlsson, L. Pilot project on labour-based road const ruction and m aintenance in T hailand. Final R eport. ILO, Geneva. 1987. Ref. No. 43050 Karlsson, L. Pilot project on labour-based road const ruction and m aintenan ce in T hailan d. Com paction by labour compatible equipm ent. ILO, Geneva . 1987. Ref. No. 43048 Labour-based rehabilitation proposal for piecework system.

Office of the P rim e Minist er, Tan zan ia. 1988. Ref. No. 37189 Labour-based road constru ction: Field book for road supervisors. Departmen t of Feeder Roads, Ghan a. 1991.

Ref. No. 26030 Lenn ar tss on, Mar ia & St iedl, David. Technology choice: Man or Machine. ILO/ASIST. 1995 . Ref. No. 42033 Marshall, J . District coun cil road u nit. T echn ical Manu al. Ministry of Local Governm ent an d Lan ds, Botswa na . 1987. Ref. No. 22076 Multi Phi Beta. Pilot labour int ensive road project. Unit ra te analysis. ILO, Ind onesia . 1996. Ref. No. 43500

36


Norconsu lt A/S. S upervision of gravelling backlog and stud y of labour-based contracting. Contractor training programme. Final report, Volum e 1. Minist ry of Work s, Kenya. 1994.

Ref. No. 27096 Norconsu lt A/S. S upervision of gravelling backlog and stud y of labour-based contracting. Prelim inary results t rial site an d contractor evaluation. Minist ry of Works, Kenya . 1992.

Ref. No. 27381 Rockbreaking and rock drilling equipm ent. Ministr y of Work s,

Lesoth o. 1986. Ref. No. 28084 Scott Wilson Kirkpa tr ick. Labour Construction Unit S tage II Report. Minist ry of Work s, Lesoth o. 1987. Ref. No. 28023 Taylor, GA. Man ual for estim ating labour intensive works in Lesotho. Minist ry of Work s, Lesoth o. 1987. Ref. No. 28124 Tuffour, AY; Ampadu, KS. A S tud y of the field perform ance of selected labour-based contractors in Ghana. In: P roceedings of th e 5 t h Regional Semina r for Labour-based Pr actitioners. ILO, Geneva . 1996. Ref. No. 26044 Work norm s for agricultu ral and rural roads. Ministr y of

Local Developm ent , Nepa l. 1998. Ref. No. 43131 Workn orm s of N ingxia w ater conservan cy agency an d t hose ad opted by th e project. Pr oject 4071, China. 1992.

Ref. No. 43194 World B ank stud y of the substitution of labour an d equipm ent in civil constru ction: A sum m ary of the engineering fin din gs.

World Ban k. 1976. Ref. No. 01370


37

ANNEX 2: Country productivity data Note: Th ere are m any gaps in the tables below. H owever, it is h oped tha t th e publication and dissemin ation of this Brief will stim ulate readers to contribute to filling in th e gaps. If you hav e relevant d ata, please send it to one of the AS IS T offices (see the ba ck cover for ad d resses).

COUNTRY DATA FOR SITE CLEARING ACTIVITIES Production targets Country Botswana Cambodia China Ghana India Kenya Lesotho Mozambique Tanzania Thailand Zimbabwe World Bank Minimum Maximum Average Median Number of records

Bush clearing Dense m² m² Min Max 20

40

Medium m² m² Min Max 750 40 80

Light m² m² Min Max 750 80 120 350

130 50 50

150

50

200 150 100

300 250

100

250

80 750 230 125 6

300 150 120 750 315 275 8

200 20 20 20 20 1

Actual output

Unit

Clearing Dense Bush Medium Bush Light Bush Grubbing <20 cm De-stumping > 20 cm Boulder removal

m2 m2 m2 m2 No No

40 200 87 50 6

40 150 95 95 2

400

80 350 215 215 2

Other clearing Grubbing De-stumping Boulder removal m² m² No No No No Min Max Min Max Min Max 150 10 20 1 1 350 30 0 30

400 45 200 100 150

200 0 350 103 30 6

300 15 15 400 153 150 9

5 1 Exp 1 2

1 2 1 1 2

5

1 5 2 1 4

15 Exp Ds

Ds

Ds

1

10

1 5 3 3 2

10 15 13 13 2

Botswana Ghana Kenya Lesotho Mozambique Zimbabwe Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max 17.4 33.9 11.3 29.2 53.8 27.5 45 35 64.9 52.5 65 27.5 31.3 75

Ds = Depends upon the size; Exp = By experience

38


COUNTRY DATA FOR EXCAVATION ACTIVITIES Production targets for excavation in cubic metres per task Country Botswana Cambodia China Ghana Indonesia Kenya Lesotho Mozambique Tanzania Thailand Zimbabwe World Bank Minimum Maximum Average Median Number of records

Soft Min Max 3.8 4.5 2.5 3.0 9.0 3.0 4.5 4.0 4.0

6.0 5.0

Medium Min Max 3.1 4.5 1.5 2.5 7.0 3.0 4.5 1.7 3.5 2.0 5.0 3.0 4.0

5.0

6.0

4.0

5.0

3.5

5.0

6.0 6.7 3.0 9.0 5.6 6.0 9

5.0

6.0 4.2 2.5 7.0 4.6 4.5 10

3.0

2.5 5.0 3.9 4.0 7

1.5 5.0 2.9 3.0 8

Hard Min Max 2.5 2.5 1.0 1.5 3.0 3.0 4.5 2.5 1.5 3.0 2.5 3.0

1.0 3.5 2.4 2.5 7

Very hard Min Max 1.9 1.9 0.5 1.0 2.0 3.0 4.5 1.5 0.5

2.0 1.5

4.5

2.0

3.0

5.0 3.0 1.5 5.0 3.3 3.0 10

3.0

4.0 2.0 1.0 4.5 2.4 2.0 9

0.5 3.0 1.8 1.9 7

Rock Min Max

0.5 0.5

1.0 1.5

1.0

3.0 1.7 1.0 3.0 1.8 1.6 4

0.5 1.0 0.7 0.5 3

Actual output of excavation in cubic metres per task Soft Medium Hard Very hard Rock Country Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Botswana 5.2 3.6 5.2 3.2 5.2 2.9 Cambodia 6.0 6.0 6.0 6.0 6.0 China 10.0 10.0 10.0 10.0 Ghana 5.0 4.1 5.0 4.1 5.0 4.1 5.1 4.2 Indonesia Kenya 4.0 3.0 5.0 2.5 5.0 2.0 1.5 1.3 5.0 Lesotho 3.3 2.9 1.4 Mozambique Tanzania Thailand Zimbabwe 5.0 5.0 5.0 4.5 5.0 4.0 5.0 3.0 World Bank Minimum 4.0 3.0 5.0 2.5 5.0 2.0 1.5 1.3 5.0 Maximum 10.0 5.0 10.0 4.5 10.0 4.1 10.0 4.2 6.0 Average 5.9 3.8 6.0 3.4 6.0 3.3 5.5 2.5 5.5 Median 5.1 3.6 5.1 3.2 5.1 3.5 5.1 2.2 5.5 Number of records 6 5 6 5 6 4 5 4 2


Max

0.9 0.7

0.7 0.9 0.8 0.8 2

39

COUNTRY DATA FOR HAULAGE ACTIVITIES Production targets for hauling in cubic metres per task Country Botswana Cambodia China Ghana Indonesia Kenya Lesotho Mozambique Tanzania Thailand Zimbabwe World Bank Minimum Maximum Average Median Number of records

0-20 m Min Max 8.4

20-40 m Min Max 7.0

40-60 m Min Max 6.7

60-80 m Min Max 5.6

80-100 m Min Max 5.2

10.5 8.0

10.5 6.0

8.0 5.0

6.5 4.5

5.5 4.0

4.5 -

5.5

5.0

5.0

4.0

10.0

12.0

10.0

12.0

5.0

5.0

10.0 5.0 10.0 12.0 10.0 8.8 10.0 8.4 1 5

10.0 5.0 10.0 12.0 10.0 8.1 10.0 7.0 1 5

7.5

9.0

6.0

5.0 7.5 7.5 7.5 7.5 1

5.0 9.0 6.7 6.7 5

6.5

5.0

5.0 6.0 6.0 6.0 6.0 1

4.5 6.5 5.6 5.6 5

5.0 5.0 5.0 5.0 1

4.0 5.5 5.0 5.2 5

100-150 m Min Max 4.7

0.0 0.0 0.0 0.0 0

4.0 5.0 4.6 4.6 4

Actual output of excavation in cubic metres per task 0-20 m 20-40 m 40-60 m 60-80 m 80-100 m 100-150 m Country Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max Botswana 5.0 6.0 5.0 5.0 5.0 4.5 5.0 4.0 5.0 3.8 5.0 3.3 Cambodia China Ghana 5.9 4.6 5.9 4.6 5.9 4.6 5.9 4.6 5.9 4.6 5.9 4.6 Indonesia Kenya Lesotho 3.5 3.5 3.5 3.5 3.5 3.5 Mozambique Tanzania Thailand Zimbabwe 5.0 9.0 5.0 9.0 5.0 8.0 5.0 7.0 6.0 6.0 6.0 5.0 World Bank Minimum 5.0 3.5 5.0 3.5 5.0 3.5 5.0 3.5 5.0 3.5 5.0 3.3 Maximum 5.9 9.0 5.9 9.0 5.9 8.0 5.9 7.0 6.0 6.0 6.0 5.0 Average 5.3 5.8 5.3 5.5 5.3 5.2 5.3 4.8 5.6 4.5 5.6 4.1 Median 5.0 5.3 5.0 4.8 5.0 4.6 5.0 4.3 5.9 4.2 5.9 4.1 Number of records 3 4 3 4 3 4 3 4 3 4 3 4

40


COUNTRY DATA FOR LOADING, UNLOADING AND SPREADING ACTIVITIES Production targets Load, unload, spread Loading soil Loading gravel Unloading soil Unloading gravel Spreading soil Spreading soil Spreading gravel Spreading gravel

Unit m3 m3 m3 m3 m3 m2 m3 m2

Production targets Load, unload, spread Loading soil Loading gravel Unloading soil Unloading gravel Spreading soil Spreading soil Spreading gravel Spreading gravel

Actual output Load, unload, spread Loading soil Loading gravel Unloading soil Unloading gravel Spreading soil Spreading soil Spreading gravel Spreading gravel

Actual output Load, unload, spread Loading soil Loading gravel Unloading soil Unloading gravel Spreading soil Spreading soil Spreading gravel Spreading gravel

Botswana Min Max 12

10

Cambodia Min Max 8 12 5 7 15 20 12 15 5 7.5

Ghana Min Max

Indonesia Min Max

3.5

10

Mo zamb iqu e Min Max Min Max

14 12

16 90 15 60

60

5

12 50

5

Kenya Min Max 8 10 8 10 8 10 8 10 12 15

6.7

50 18

L eso th o Unit m3 m3 m3 m3 m3 m2 m3 m2

China Min Max

Tanzania Min Max 12 15 7 10

15 60

75

Thailand Min Max

18 90 12 60

35

15

50

Zimbabwe Min Max 8

9

7

10

World Bank Min Max

11

10

Botswana Cambodia China Ghana Indonesia Kenya Unit Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max m3 6 6 9 m3 6 6.25 6.5 6 9 m3 6 9 m3 6 12.7 6 9 m3 6 m2 5.4 91 6 13 m3 6 6 13 m2 5.8 86

Lesotho Unit Hr/task m3 m3 m3 m3 m3 m2 m3 m2

Mozambiqu

Tanzania

e Max Hr/task Max Hr/task

Thailand

Max Hr/task


Zimbabwe

World Bank

Max Hr/task Max Hr/task 5 6 5 6 5 11 5 11 5 11 5

Max

11

41

COUNTRY DATA FOR COMPACTION ACTIVITIES Production targets Handrammer Country Botswana Cambodia China Ghana Indonesia Kenya Lesotho Mozambique Tanzania Thailand Zimbabwe World Bank Minimum Maximum Average Median Number of records

Formation m³ Min Max 10.0

Structures m³ Min Max

12.5 5.7

8.0

10.0

8.0 10.0 9.0 9.0 2

5.7 12.5 9.4 10.0 3

Slopes m³ Min Max 7.5

10.0 1.5

2.5

6.0

9.0

6.0

9.0

6.0 6.0 6.0 6.0 1

2.5 9.0 5.8 5.8 2

6.0 7.5 6.8 6.8 2

1.5 10.0 6.8 9.0 3

Production targets Mechanical Formation m³ Min Max

Country Botswana Cambodia China Ghana Indonesia Kenya Lesotho Mozambique Tanzania Thailand Zimbabwe World Bank

250.0 170.0 280.0

Minimum Maximum Average Median Number of records

75.0 16.7 170.0 280.0 115.0 156.1 100.0 145.0 3 6

42

75.0 100.0 16.7

Structures m³ Min Max

Slopes m³ Min Max 10.0

Structures m² Min Max

Structures m² Min Max

13.5

100.0 150.0

700.0

140.0

700.0

10.0 10.0 10.0 10.0 1

Slopes m² Min Max

13.5 13.5 13.5 13.5 1

0.0 0.0 0.0 0.0 0

700.0 700.0 700.0 700.0 2


COUNTRY DATA FOR CULVERT LAYING ACTIVITIES Production targets Compaction Culvert laying 600 mm 900 mm Concrete work Stone masonry

Unit

Compaction Culvert laying 600 mm 900 mm Concrete work Stone masonry

Compaction Culvert laying 600 mm 900 mm Concrete work Stone masonry

L eso th o Unit m m m3 m3

Min Max 1

1.1

1.5 1.2

2 1.5

6

12

1 1

1.5 1.5

Mo zamb iqu e Min Max

China Min Max

Ghana Min Max

Indonesia Min Max

Kenya Min Max

1.4 0.9 0.2

0.1

Tanzania Min Max 0.36

0.33 0.33 1 1.5

Thailand Min Max

Zimbabwe

World Bank Min Max

Min Max 0.5

0.9

0.6 0.5

1 1

Botswana Cambodia China Ghana Indonesia Kenya Unit Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max m m m3 m3

Actual output Compaction Culvert laying 600 mm 900 mm Concrete work Stone masonry

Cambodia Min Max

m m m3 m3

Production targets

Actual output

Botswana Min Max

7

5

7 7

6 6

0.28 0.3

Lesotho Unit Hr/task m m m3 m3

7 7 7 7

Mozambiqu Tanzania Thailand Zimbabwe World Bank e Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max Hr/task Max 1 0.8 0.5 0.5


0.9 1 1

43

ANNEX 3: Labour productivities in construction works — a historical perspective By Gary Taylor, I. T. Tran sport, UK

Ther e is, of cour se, nothin g new about th e use of labourbased m eth ods for major engineering pr ojects. The grea t building feats of all cent ur ies prior t o the pr esent one were largely carr ied out by han d labour. It is th erefore int eresting to compare curr ent labour -based pr ojects with t hose of ear lier periods, pa rt icula rly in respect of labour produ ctivities for comm on opera tions. However, it is quite difficult to obtain s ta tist ics a bout labour pr oductivities for engineering projects carried out more tha n one hu ndr ed years a go. One of th e reasons for t his is th at ma ny projects were carr ied out by forced or bonded labour an d outpu t per day was n ot someth ing closely monitored. F or examp le, we kn ow from historian s th at t he Great P yramid of Egypt was built in about 2500 BC with either 300,000 men , according to Diodoru s Siculus , or 100,000 men , according to Herodotus , in about twenty years. The size of the pyramid is 230 metr es squar e and 147 metres high, and it ha s been estimat ed tha t it is cons tr ucted from 2,300,000 blocks of limest one of bet ween 2.5 to 15 tonn es each. The labour expen ded in t he bu ilding of th e pyram id ha s been calculat ed (by Lecount 4 2 ) as t he equivalent of liftin g 136 m illion cubic met res of stone one met re h igh. This su ggests an “avera ge” productivity of between 0.1 an d 0.3 cubic metr es of st one lifted one met re per ma nda y — not such a useful sta tistic, and one h edged ar oun d by various un certa inties over th e exact cont ent an d cont inuity of th e work! The Great Wall of China is anoth er examp le of a m assive engineering u ndert aking carried out by labour -intensive meth ods. The 2,250 kilometre long wall was bu ilt aroun d 200 BC an d is estima ted t o have occupied 500,000 work ers. The wall is eight m etres high an d six metr es wide and its t otal volume is about 100 million cubic met res. If th e wall took, say, 20 year s to build, th e avera ge labour p roductivity would be ar ound 0.2 cubic met res of st one lifted one m etr e per ma nda y. Tha t is probably of th e sam e order of productivity as for t he Great Pyram id, but again it is difficult t o bring th is to un its which we can compa re with pr oductivities on cur ren t day labour -based p rojects. The building of th e can als in E ur ope an d America from the late eight eenth centu ry onwar ds was th e beginning of an era of large-scale p ublic work s cons tr uction by la bour-inten sive met hods. Initially th e typical system of labour recru itmen t was for th e compa nies which were formed to const ru ct an d operat e th e works to hire labour directly. Their main 42

44

History of th e Railway Connecting London a nd Birm ingham , Lecount, 1839.


interest wa s to engage labour on terms which, as far as possible, boun d t he labourers to th eir employment for th e period r equired for th e works. Th ey paid labour on a “days worked” bas is an d relied on overseer s to achieve high productivity thr ough diligent supervision a nd t he enforcement of long working h ours. Consequen tly, it is a gain difficult t o obtain compa ra tive labour productivity dat a. Gradu ally th ere was a s hift t o the use of contra ctors, and in th e great r ailway-building era of th e mid-nineteent h centu ry, severa l large an d successful civil engineerin g contr actors emerged. This was a ccompa nied by a move on t he pa rt of cont ra ctors t o th e use of incentives to motivat e high pr oductivity from t heir la bour forces. These incentives varied, but th e most widespread a nd su ccessful was th e use of “piece work” — paymen t bein g based on outp ut . In 1864 it was reported th at, in th e building of th e Suez Can al “th e great er pa rt of th e excava tion is by piece work , for which excellent resu lts ar e obta ined...”43 . This contra sted with a d ifficult period before 1864 when forced labour ha d been used for t he ear ly part of the const ru ction work. The use of piecework brought m uch greater at tent ion t o the daily out put of labour, and some extra ordina ry feats are reported. In th e building of the Blackstone Can al in North America, san d was r emoved by ox-dra wn cart s: six labour ers loaded 50 carts per h our 44 . Assuming each cart held at least 0.25 cubic metr es, th is equa tes t o a pr oductivity of 2.1 cubic metr es per hour per m an , or 16.5 cubic metr es per man per eight-hour day. In a nother u nu sual feat of labour , three Irishmen on th e Erie Can al du g 228 cubic metres in five and a ha lf days of work. This equates t o 14 cubic metr es per ma n per day. This is reported to have been about th ree times the norma l avera ge, which m ust th en h ave been approximat ely 4 to 5 cubic metres per man day. By furt her compar ison, slaves working on t he San tee Can al some time ear lier, in t he 1790s, were expected to move about t wo cubic met res per d ay. Thomas Bra ssey was one of th e most su ccessful of th e British ra ilway cont ra ctors of th e nineteent h centu ry. At certain periods in his career, he an d his par tn ers were giving employment to 80,000 people45 . One of his agent s gives precise inform at ion on th e avera ge amoun t of labour done by th e English “na vvies”, the na me given to th e labour ers enga ged on t he ha rdest ph ysical work of ra ilway building. He sa id th at a full day’s work cons isted of fourt een set s 46 . A “set ” is a n umber of wagons — in fact a tr ain. There were two men to a wagon. Therefore each ma n excavated a nd filled the equivalent of seven wagons per da y. Ea ch wa gon cont ain ed just over t wo cubic met res. Th erefore ea ch m an load ed over 14 cubic metres per day, an d th e height of lift wa s about 1.8 Sue: De Lessep’s Can al, J ohn P udney, 1968 (p.109) Common Labour; Worker s an d th e Digging of Nort h American Ca na ls 17801860, Peter Way, 1993 (p.137) 45 Life an d Labours of Mr Bras sey, Art hu r H elps, 1872 (p.160) 46 Ibid. (p.77) 43 44


45

prod_norms

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