INTRODUCTION Skid resistance is very important parameters that need to be considered in designing the highway. The skid resistance is important to ensure that the vehicles that use the road under the design speed do not slide. Skid resistance is a force that is developed when the vehicle tyre is on contact with the surface pavement. The road designer must ensure that the force developed must be enough to ensure the vehicle does not slide.
One of the surface requirements of road pavement is that it should posses adequate skid resistance. Skid resistance is important for road safety. With skid resistance it allows for better 'grip' between tire and road surfaces. Most road surfaces have adequate skid resistance in the dry as compared during wet condition. The presence of water between the tire and road surface reduces the contact area which are needed to create the 'grip'.
OBJECTIVE The objective of the experiment is to determine the skid resistance value, for different type of microtexture on the road pavement surface by performing skid resistance test.
APPARATUS
Skid Resistance Tester
PROCEDURE 1. The skid resistance tester was setup at the location. 2. The bubble was adjusted to be at the middle by adjusting the three adjusting the levelling screws at the base of the skid resistance. 3. The height was adjusted until the friction plate touches the pavement surface. 4. The pendulum arm was placed at the starting point. 5. The maximum swing indicator was set to zero. 6. The pendulum arm was released and catched to prevent backswing of the pendulum arms. 7. The result was taken for the wet and dry condition. 8. The procedure was repeated for the medium and fine surface.
RESULT Type of surface
Dry
Wet
(130+132+135)/3
(114+111+114)/3
(car park)
= 132.33
= 113
Medium
(124+127+126)/3
(75+70+68)/3
(motorcycle park)
= 125.67
= 71
Fine
(83+91+89+91+90)/5
(81+79+81+80+81)/5
(concrete)
= 88.8
= 80.4
Coarse
DISCUSSION
From the skid resistance test that we have done, we found that the skid resistance value is different for 3 types of surface, for both dry and wet condition. We found that the value of skid resistance is highest on the coarse surface and the lowest value of skid resistance is on the fine surface. What we can discuss is, we found that the value of skid resistance is different because of the surface macro-texture of the pavement. For the highest value of the skid resistance, the surface texture of the pavement is coarse which have average texture depth greater than 0.5mm. This type of pavement is suitable for roundabouts, road with bends with radius less than 150m on unrestricted roads, road with gradients 1 in 20 or steeper of lengths greater than 150m. Other than that, this type of pavement is also suitable for wet climate region which rain often occurs on that place. For the medium value of the skid resistance, it has an average texture depth from 0.25mm to 0.5mm. This type of surface pavement is suitable for motorways, trunk and class 1 roads and heavily trafficked roads in urban area which carry more than 2000 vehicles per day. For the lowest value of skid resistance, the surface pavement has a very fine texture. It is suitable for any other sites that rarely used by vehicle. More than that, hot climate region also suitable for this type of pavement. With fine surface of pavement, the intensity of the tyre thread to be burn can be lowered as compared with the friction of the tyre on the course surface pavement.
SAFETY AND HEALTH Student must use safety jacket during the experiment in order to make sure the safety of ourselves. Traffic cone is used to aware any vehicles that approaching the location of experiment. Group leader should advice and look after the other members. Students also have to make sure the experiment is conducting opposite the road so that aware with the vehicles approaching the location of the experiment.
CONCLUSION
In this experiment, we can conclude that pavement have many type of microtexture for difference suitable function for every type. The skid resistance values show us the friction between tyre and the microtexture. The objective of the experiment is achieved.
REFERENCE 1. Laboratory manual. 2. Skid resistance test, nanyang technology university, school of civil engineering https://www.google.com.my/url? sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwjrkMC9qNDPAhXLpo8 KHbgYCVMQFggbMAA&url=http%3A%2F%2Fwww3.ntu.edu.sg%2Fcts%2Ftlab %2F006.pdf&usg=AFQjCNHgYdnplCn71l28f1anzIf1l_dwig&bvm=bv.135258522,d. c2I&cad=rja
