THE SAFE STOPPING SIGHT DISTANCE SHOULD INVARIABLY BE PROVIDED THROUGHOUT THE LENGTH OF ALL ROADS, DESIGNED FOR THE PARTICULAR SPEED ALLOWED ON THE ROAD

The alignment of hill roads should ensure clear visibility up to the minimum stopping sight distance all along the length. It will be impracticable normally to provide visibility corresponding to the overtaking sight distance. Vision berms should be provided on the inside of the horizontal curves up to a height of 0.6 metres. The width of these berms should equal the set-back distance minus the width of drain. While designing for the safe visibility distance, it should not be ignored that drivers visual difficulty is magnified by, hazy visibility during the monsoons. The sighting distance provided on roads should not be less than the safe Stopping distance for the particular speed allowed on the road. Where the minimum stopping distance cannot be provided, warning boards should be fixed for reducing the speed. For the purpose of measuring the stopping sight distance or visibility ahead, IRC has suggested the height of the eye level of driver as 1.2 metres and the object height as 0.15 metre above the road surface. Hence stopping distance at a summit curve is that distance measured along the road surface at which an object of height 0.15 metre can be seen by a driver whose eye is at a height of 1.2 metres above the road surface. The minimum sight distance should be based on the accepted speed of the vehicles and the breaking distance required to stop and which should also include the driver's reaction time to the danger. The safe sight distance is dependent on the breaking time of the vehicle and is generally taken as being equal to twice the distance required for a vehicle to stop. Mechanical and human factors should be taken into account-- the breaks may be defective, the driver may be drunk, and these factors will need more of stopping distance and the reaction time. Hence the safe stopping sight distance should invariably be provided throughout the length of all roads:-- Er Fateh chand Guleria, Director RTI, Welfare Association registered number HPCD, 3552 , Bilaspur HIMACHAL PRADESH Phone number, 9459334377