2020 Volume 6 Issue 2 Pages A_198-A_205
At the planning stage of road projects, their feasibility is evaluated by the cost-benefit analysis (CBA). In this process, the speed flow relationship (Q-V formula) based on the road type is being used for traffic assignment in Japan. However, in road projects such as grade separation of intersections, if the traffic volume is unchanged through the project, the estimated travel speed is also unchanged, and the effects of the project cannot be properly reflected to the CBA. In this paper, the impact of signalized intersection density on the free speed of the Q-V formula is analyzed by using a traffic simulator. An impact of benefit that is sensitive to the grade separation of intersections by using the calculated free speed is evaluated. As a result, it was confirmed that the free speed of the Q-V formula changes based on the signalized intersection density, the green time ratio and the desired speed. Finally, three benefits of road projects were calculated by a proposed Q-V formula using the free speed based on the signalized intersection density. And the effect of the new formula was clarified by showing the difference in benefits compared to the conventional method.
