01660244

Component

Speed is a fundamental measure of traffic performance of a roadway system. It indicates the quality of service experienced by the traffic stream and it depends on traffic volume or density on the road. In a mixed traffic situation, congestion (or pavement occupancy) on a section will depend upon the number of vehicles of different categories in the traffic stream. For the same value of traffic volume, a vehicle may experience different congestion levels depending upon the proportional share of large size vehicles like heavy vehicles and small size vehicles like motorized two-wheelers. Hence the speed of a vehicle type will depend upon the total density on the road and this total density comprises of densities of individual vehicle types. In the present study field data were collected on different sections of four-lane urban arterials in New Delhi, Jaipur and Chandigarh by video recording method. The speed flow data collected from field shows the parabolic relationship between flow and speed that reproduce the linear speed-density relationship. The present study extends this linear speed-density relation to mixed traffic condition and attempts to develop a set of simultaneous equations relating speed of a vehicle type to the densities of all categories of vehicles in their individual terms. These equations are solved for some assumed values of traffic volume and traffic composition and effect on speed of each vehicle type is explained. It has been observed that there is a gentle reduction in speed of two wheelers from low flow level to the capacity level of flow whereas at the same time reduction in speed of heavy vehicles is steeper for the same flow range. It has been explained on the basis of vehicle manoeuvrability. Two wheelers are small in their physical size and because of better manoeuvrability as compared to the heavy vehicles can able to maintain the speed at high flow level. The degree of damaging effect on speed of heavy vehicle at the same time is high because of poor manoeuvrability. Accuracy of the equations is checked by comparing the observed values of speed with calculated speeds from simultaneous equations.

This paper was sponsored by TRB committee AHB40 Standing Committee on Highway Capacity and Quality of Service.

18-02567

English

16p

2018

Transportation Research Board 97th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Arterial highways; Four lane highways; Mathematical models; Mathematical prediction; Simultaneous equations; Urban highways; Vehicle mix

Speed prediction models

Highways; Operations and Traffic Management

Transportation Research Board Annual Meeting 2018 Paper #18-02567

TRIS, TRB, ATRI

Jan 8 2018 10:37AM