Simulation of mixed traffic flow on two-lane roads

Data were collected at several locations of two-lane roads in different parts of India and were analyzed to study the speed, placement, arrival, acceleration, and overtaking characteristics of different types of vehicles. A computer program is developed to simulate the traffic flow on a two-lane highway incorporating all these characteristics. The simulation program is coded in Visual Basic language and has also been animated. A number of simulation runs were performed to determine the capacity of a two-lane road and to study the effect of traffic mix on capacity and speed. The passenger car unit (PCU) for an individual category of vehicles is calculated and the effect of directional split on capacity is evaluated. Capacity of a two-lane road under an all cars situation is estimated as 2,860 PCU/h. It increases to 5,600 vehicle per hour (vph) in case of all two-wheelers and reduces to 580 vph in case of all tractors situation. The capacity also reduces as the directional split moves away from an even split of 50/50 and this reduction is linear. It is further observed that the capacity of a two-lane road decreases as the proportion of three-wheeler, tractor, or heavy vehicle increases in the traffic stream. But, in the case of two-wheelers the capacity was found to increase with their own proportion. This is attributed to the small size of two-wheelers and their maneuverability.