Answer to Question #281443 in Civil and Environmental Engineering for Riyan Malik

Question

As a part of traffic management measure, it is proposed to ban the heavy vehicle from a city street. It has been observed that the mean free speed is 60 km/hr. The percentage flow is 1200 veh/hr. per lane, the composition being: Private Cars: 80, Commercial vehicle: 09 and Buses: 11. The average occupancy of the vehicle is privale cars: persons per cars and Buses: 35 persons per bus. 2%, After the commercial vehicles are banned, it is expected that 15% new cars are in the street and attraction 10% of cars in the street. But the average space occupied for new and attractive cars 1.0 persons per car. The average space occupied by each types of vehicles when stationary in the jamming condition is: Private car: 6m, commercial vehicles: 10m and bus: 8m. Find: (i) The maximum capacity of the street before and after the imposition of the ban on heavy vehicles. (ii) The mean speed of traffic in km/hr. before and after the imposition of the ban on heavy vehicles.

Answer 1

Traffic congestion is a condition in transport that is characterised by slower speeds, longer trip times, and increased vehicular queueing. Traffic congestion on urban road networks has increased substantially, since the 1950s.^[1] When traffic demand is great enough that the interaction between vehicles slows the speed of the traffic stream, this results in some congestion. While congestion is a possibility for any mode of transportation, this article will focus on automobile congestion on public roads.

One of the most frequently used methods of managing travel speeds is the posted speed limit. The setting of speed limits predates the automobile by some 200 years, when Newport, Rhode Island, prohibited the horses galloping on major thoroughfares to prevent pedestrian deaths. Similarly, Boston, Massachusetts, limited horse-drawn carriages to "foot pace" on Sundays to protect church-goers.

Selecting an appropriate speed limit for a facility can be a polarizing issue for a community. Residents and vulnerable road users generally seek lower speeds to promote quality of life for the community and increased security for pedestrians and cyclists; motorists seek higher speeds that minimize travel time. Despite the controversy surrounding maximum speed limits, it is clear that the overall goal of setting the speed limit is almost always to increase safety within the context of retaining reasonable mobility.

PURPOSE AND SCOPE

Despite the wide-spread acceptance and use of speed limits throughout the world, there has been no consensus among practitioners concerning the methods and techniques that should be used to select the most appropriate speed limit for a particular facility. Currently, it appears unlikely that consensus will be achieved in the near future. This leaves practitioners without definitive guidance on this important issue, and in search of information that may assist them. This report provides the information necessary for practitioners to make informed decisions concerning the method that is selected for setting speed limits in their jurisdiction.