How Wide the Roadway Should Be: A Continuous Model on the Roadway Design in a Corridor City

This paper discusses the roadway design problem in a corridor city. The residents are located along the corridor and each individual makes work trip to the CBD at the end-point of the corridor. The government is assumed to build an artery roadway on this corridor to satisfy the trip demand along the corridor. The optimal road width, a function of the distance away from the CBD, could be a benchmark for evaluating the roadway design. It was found that if the roadway is constructed according to the optimal width, the road will keep on the same congestion level along the corridor, namely the demand/width ratio keeping constant. Furthermore, the commuters´ trip cost will increase linearly with the distant from their residence to the CBD. Additionally, if the local authorities levy the optimal road congestion price along the corridor, the total revenue of road pricing can just cover the total construction cost of the road.