DyETC: Dynamic Electronic Toll Collection for Traffic Congestion Alleviation (2018)
Haipeng Chen, Bo An, Guni Sharon, Josiah Hanna, Peter Stone, Chunyan Miao, and Yeng Chai Soh
To alleviate traffic congestion in urban areas, electronic toll collection (ETC) systems are deployed all over the world. Despite the merits, tolls are usually pre-determined and fixed from day to day, which fail to consider traffic dynamics and thus have limited regulation effect when traffic conditions are abnormal. In this paper, we propose a novel dynamic ETC (DyETC) scheme which adjusts tolls to traffic conditions in realtime. The DyETC problem is formulated as a Markov decision process (MDP), the solution of which is very challenging due to its 1) multi-dimensional state space, 2) multi-dimensional, continuous and bounded action space, and 3) time-dependent state and action values. Due to the complexity of the formulated MDP, existing methods cannot be applied to our problem. Therefore, we develop a novel algorithm, PG-beta, which makes three improvements to traditional policy gradient method by proposing 1) time-dependent value and policy functions, 2) Beta distribution policy function and 3) state abstraction. Experimental results show that, compared with existing ETC schemes, DyETC increases traffic volume by around 8 percent, and reduces travel time by around 14.6 percent during rush hour. Considering the total traffic volume in a traffic network, this contributes to a substantial increase to social welfare.
In Proceedings of the 32nd AAAI Conference on Artificial Intelligence (AAAI-18), New Orleans, Louisiana, USA, February 2018.

Josiah Hanna Ph.D. Student jphanna [at] cs utexas edu
Guni Sharon Postdoctoral Fellow gunisharon [at] gmail com
Peter Stone Faculty pstone [at] cs utexas edu