PAVEMENT CONDITION INDEX METHOD compiled by Basil David Daniel
Main Reference: M.Y. Shahin, Pavement Management for Airports, Roads and Parking Lots, Springer, New York, 2005
Pavement Condition Index (PCI) Method Background
The Pavement Condition Index (PCI) method is used to obtain a Pavement Condition Index (PCI) value for pavements through a visual survey of the pavement. The Pavement Condition Index (PCI) is a numerical rating of the t he pavement condition that ranges from 0 to 100 (refer to Figure 1), with 0 being the worst possible condition and 100 being the best possible condition. The Pavement Condition Index (PCI) method was developed by the Construction Engineering Research Laboratory of the U.S. Army Corps of Engineers. This method can be used on both asphalt surfaced as well as jointed portland cement concrete (PCC) pavements.
Figure 1: Pavement Condition Index (PCI) Rating Scale and the corresponding Level of Service and Maintenance Activity
Performing a Pavement Condition Survey on Asphalt Surfaced Pavements
Equipment: Inspectors need a hand odometer or measuring tape to measure distress lengths and areas, a straight edge, a ruler to measure the depth of ruts or depressions, and the PCI distress manual (to assist in identifying distresses and determining their severity levels). Procedure: A sample unit is inspected by measuring the distress type and severity according to the PCI distress manual, and recording the data on the flexible pavement survey sheet (as shown in Figure 2). One data sheet is used for each sample unit.
Figure 2: Pavement Condition Survey Sheet
Dividing a Pavement Section Into Sample Units
A sample unit is defined as the portion of pavement section designated only for the purpose of pavement inspection. Figure 3 shows an example of sample units.
Pavement Section 6.5 m x 780 m
1
2
3
100 m
100 m
100 m
4 100 m
5
6
7
8
100 m
100 m
100 m
80 m
Figure 3: Example of a pavement section divided into sample units
The number of sample units in a pavement section to be inspected can be determined using Figure 4. When performing initial inspection, the PCI standard deviation for asphalt concrete is assumed to be 10.
Figure 4: Selection of the minimum number of sample units
It is recommended that the sample units to be inspected be spaced equally throughout the section, and that the first one be chosen at random (this technique is known as ‘systematic random’). Sampling interval is determined using the following equation: Interval, i =
N
where N = total number of sample units in section
n
n = minimum number of sample units to be inspected The sampling interval is rounded off to the smaller whole number (e.g. 3.6 is rounded to 3).
Example:
If N = 20, n = 9 (determined from Figure 4) Interval, i = 20/9 = 2.2
≈
2.0
Hence sample units to be inspected are 1, 3, 5, 7, 9, 11, 13, 15 and 17 (as indicated in Figure 5). 1
2
3
4
5
6
7
8
9
10
11
12
13
14
Figure 5: Sampling interval
15
16
17
18
19
20
Example The table below shows a pavement condition survey for sample unit 07, section JPB-KM2 of Jalan Parit Botak. Determine the Pavement Condition Index for this sample unit. JALAN PARIT BOTAK (ASPHALT SURFACED ROAD) CONDITION SURVEY DATA SHEET BRANCH: TRAFFIC LABORATORY UTHM DATE: 25 AUGUST 2007 SURVEYED BY: BDD SAMPLE UNIT: 07 SECTION: JPB-KM2 SAMPLE AREA: 6 m x 100 m 2 2 01. Alligator Cracking (m ) 06. Depression (m ) 11. Patching & Utility 2 2 02. Bleeding (m ) 07. Edge Cracking (m) Cut Patching ((m ) 2 03. Block Cracking (m ) 08. Joint Reflection 12. Polished 2 04. Bumps and Sags (m) Cracking (m) Aggregate (m ) 2 05. Corrugation (m ) 09. Lane/Shoulder Drop 13. Potholes (no.) Off (m) 14. Railroad Crossing 2 10. Longitudinal & (m ) 2 Transverse Cracking 15. Rutting (m ) (m) DISTRESS QUANTITY TOTAL SURVEY
03 M 01 L 01 H 11 M 13 M 10 L 10 M
7.8
4.1
2.5
4.2
1.8
6.3 3.1
0.4
0.5
0.8
0.8
1.2
0.3
0.7
1.1
0.4
0.5
2
16. Shoving (m ) 17. Slippage Cracking 2 (m ) 2 18. Swell (m ) 19. Weathering/ 2 Ravelling (m )
DENSITY %
DEDUCT VALUE
Solution:
(1)
Determine the Distress Density and Deduct Value
DISTRESS SURVEY
03 M 01 L 01 H 11 M 13 M 10 L 10 M
(2)
QUANTITY
7.8
4.1
2.5
4.2
TOTAL
11.9 1.8
8.5
6.3
6.3
3.1
0.4
3.5
0.5
0.8
1.3
0.8
1.2
0.3
0.7
1.1
0.4
0.5
2.8 2.2
DENSITY %
100*(11.9/600) = 1.98 100*(8.5/600) = 1.42 100*(6.3/600) = 1.05 100*(3.5/600) = 0.58 100*(1.3/600) = 0.22 100*(2.8/100) = 2.80 100*(2.2/100) = 2.20
DEDUCT VALUE
6 13 32 7 50 2 6
Maximum allowable number of deducts, m
Highest deduct value, HDV = 50 m = 1 + (9/98)(100 – HDV) = 1 + (9/98)(100 – 50) = 5.6 Deduct values in descending order: 50, 32, 13, 7, 6, 6, 2 Number of deduct values = 7 Since the maximum allowable number of deducts is 5.6, therefore only the first 5 and 0.6 of th the 6 deduct value are selected, i.e. 50, 32, 13, 7, 6, and 0.6*6 = 3.6.
(3)
Maximum corrected deduct value, CDV
Number of deduct values greater than 2, q = 6 Total deduct value = 50 + 32 + 13 + 7 + 6 + 3.6 = 111.6 From Figure B-45, CDV = 58 Reduce the smallest individual deduct value to 2 (q is now 5) and determine the CDV. Repeat until q reaches 1.
No. 1 2 3 4 5 6
Deduct Values
Total
q
CDV
50
32
13
7
6
3.6
111.6
6
58
50
32
13
7
6
2
110
5
58
50
32
13
7
2
2
106
4
61
50
32
13
2
2
2
101
3
65
50
32
2
2
2
2
90
2
63
50
2
2
2
2
2
60
1
60
7 8 9 10
Maximum CDV = 65
(4)
Determine the Pavement Condition Index
PCI = 100 – CDV max = 100 – 65 = 35 Based on the rating for PCI value of 35, this section of pavement is in very poor condition.
APPENDIX Asphalt Concrete Roads: Deduct Value and Corrected Deduct Value Curves
