01475067

Component

The shortest path problem is very important in transportation field, but limited researches have considered intersection delays caused by traffic signals and queuing vehicles when seeking shortest path. When considered, the traffic signal was mostly modeled as fixed timing. Delays caused by queuing vehicles were seldom considered. Consequently, shortest path problem considering traffic signals is usually deterministic. In the case of actuated traffic signal control, however, the intersection delays are stochastic in nature. In addition, the delays experienced by a vehicle at a downstream intersection may depend on the delays it experiences at upstream intersections. In this paper the shortest path problem considering traffic signals is modeled based on the theory of Markov decision problem (MDP). The delays caused by actuated traffic signals as well as by queuing vehicles are included in the formulation. The problem is first formulated as an infinite horizon and countable state space MDP with absorbing state set. This formulation allows the intersection delays to be considered as stochastic and delays experienced by a vehicle at downstream intersection will depend on those at upstream intersections. As the MDP with countable state space cannot be solved directly in practice, a corresponding finite state space MDP is formulated taking advantage of the cyclic property of traffic signals such that the optimal policy can be solved for using value iteration algorithm. The output of the algorithm will be an optimal policy instead of a single optimal path. We show that the required input information for the model can be estimated from high resolution traffic data obtainable from field and numerical tests are carried out at the end.

This paper was sponsored by TRB committee ADB30 Transportation Network Modeling.

01470560

13-4988

English

17p

2013

Transportation Research Board 92nd Annual Meeting

Digital/other

Figures; References; Tables

Markov processes; Shortest path algorithms; Traffic actuated controllers; Traffic queuing; Traffic signals

Data and Information Technology; Highways; I71: Traffic Theory

Transportation Research Board Annual Meeting 2013 Paper #13-4988

TRIS, TRB, ATRI

Feb 5 2013 12:57PM