Impact of vehicular lateral placement on speed under non-lane discipline traffic stream

The vehicles plying on the roads of developing nations such as India are mixed in nature and do not follow any lane markings. The vehicles can easily take place laterally on any free space across the road section anticipating better maneuverability on the next time step. The vehicles usually maintain different speed for faster and safer forward movement on the next time step. Therefore, this study aims to find the relationship between vehicular speed and lateral placement. For this purpose, two hrs traffic video data were collected from VIP Road, Kolkata, India. From the traffic video film, vehicle trajectories were extracted using image processing software TRAZER after applying appropriate corrections. From the lateral placement distribution of each category of vehicles, it is observed that LMV prefers median lane, whereas MTW and MThW prefer shoulder lane. Speed-placement models were developed for all vehicles clustered and each category of the vehicle using the first hour data. It was observed that the relationship between average speed and lateral placement is linear up to a certain distance from the median edge and quadratic for the remaining portion of the road width. The speed-placement models’ validation using second-hour data indicate that the developed models are highly accurate in terms of MAPE. The results obtained in this study may be used as an input parameter while assigning vehicular speed based on lateral placement for analyzing non-lane discipline traffic stream using the simulation model.