Maximum flow in road networks with speed-dependent capacities – application to Bangkok traffic

• Main Authors: Elvin J Moore, Wisut Kichainukon, Utomporn Phalavonk
• Format: Article
• Language: English
• Published: Prince of Songkla University 2013-08-01
• Series: Songklanakarin Journal of Science and Technology (SJST)
• Subjects: maximum traffic flow; flow-dependent capacities; Ford-Fulkerson algorithm; Bangkok roads
• Online Access: http://rdo.psu.ac.th/sjstweb/journal/35-4/35-4-15.pdf

A road network can be modeled as a graph with a set of nodes representing intersections and a set of weighted edgesrepresenting road segments between intersections. In this paper, a traffic flow problem is studied, where edge weightsrepresent road capacities (maximum vehicles per hour) that are functions of the traffic speed (km/hr) and traffic density(vehicles per kilometer). To estimate road capacities for a given speed, empirical data on safe vehicle separations for a givenspeed are used. A modified version of the Ford-Fulkerson algorithm is developed to solve maximum flow problems with speeddependent capacities, with both one-way and two-way flows allowed on edges and with multiple source and target nodes.The modified algorithm is used to estimate maximum traffic flow through a selected network of roads in Bangkok. It was foundthat the maximum safe traffic flow occurs at a speed of 30 km/hr.