DESIGN STANDARDS OF THE ROADS ARE RELATED TO ACCIDENTAL RISKS FOR WHICH COMPUTATION OF THE TRAFFIC FOR USE OF CBR IS NECESSARY.

Accidental risks are related to the accuracy of road design standards for which it is necessary to design the standard of roads as per the volume of vehicles accounted for the prescribed measures by the study of density of traffic as such the accident risk to pedestrians on a zebra crossing at a high speed intersection (average vehicle speed more than 35 km/hr)is more than twice the risk to pedestrians at a low speed intersection with identical road standard .The risk to cyclists seems to be much higher then to pedestrians in location with the same road design standard.Experiments conducted in this behalf indicate that there are twice as many accidents at cross roads than Y junctions at a speed limit of 50 km per hour and four times more at 80 km/hr .At cross roads there are twice as many accidents at 80 km/hr ,as at 50 km/hr .The effects of channelising the traffic flow results in a fifty percent reduction in accidents .Some Engineers however disagree about the worth of staggered intersections .It is considered that besides providing a poorer service,it is more dangerous for crossing the roads .The summit radii in the longitudinal alignments and the radii of bends in the horizontal alignment should be made as long as possible for changing the visibility conditions arising from the lower driving positions of the more modern cars that are coming up .The overtaking visibility distance should be provided on as a great percentage of the length of the road and as uniformly as possible.It is necessary to have computation of traffic required for the use of CBR and distribution of traffic over the carriage way the traffic is considered in the units of the commercial vehicles.(1) Single -lane roads 3.75 Mt wide :-- The design is based on the total number of commercial vehicles per day in both directions, multiplied by two .(2) Intermediate width roads 5.5 Mt width :--The design should be based on the total number of commercial vehicles per day in both directions multiplied by 1.5 .(3) Two -lane Single carriage way roads:-- The design is based on 75 percent of the total number of commercial vehicles in both directions.(4) Four -lane Single carriage way roads :- The design should be based on 40 percent of the total number of commercial vehicles in both directions.(5) Dual Two lane carriage way roads :--The design should be based on 75 percent of the number of commercial vehicles in each direction and the distribution factor shall be reduced by twenty percent for each additional lane of the road .