Design of ETC Violation Enforcement System
for Non-payment Vehicle Searching
Guo-Huang Hsu*, Liang-Rui Lin**, Rong-Hong Jan**, Chien Chen***ITRI(Industrial Technology Research Institute), Hsinchu, Taiwan R.O.C.
**Department of Computer Science, National Chiao Tung University, Hsinchu, Taiwan R.O.C.
GHHsu@itri.org.tw, {ljlin, rhjan, chienchen}@cs.nctu.edu.tw

Abstract—As we know, the heaviest traffic congestion on highways occurs near toll gates where vehicles make a short stop to pay thetoll. So an electronic toll collection (ETC) system is usually built to eliminate the traffic jams. In order to find out the non-payment
vehicles, the violation enforcement usually includes cameras to capture images of license plates, and a license plate reader system torecode photographs and license plate numbers of all vehicles. Thus, automatic license plate recognition (ALPR) technology is often usedin violation enforcement. However, the identification precision of ALPR is not always reliable. Human review and correction will beneeded to improve the accuracy and therefore will result in extra manual operation cost. In this paper, we consider multilane-free-flow
ETC systems and formulate the non-payment vehicle searching problem into a matching problem and propose a
Photograph-to-Transaction matching algorithm (PT algorithm) based on bipartite graph. The PT algorithm not only can reduce thehuman loading to review and correct the image recognition results but also can accurately identify all non-payment vehicles. The
performance of the PT algorithm was evaluated in ns-2 simulator and three different traffic scenarios: congested traffic, normal trafficand sparse traffic. The simulation results show that our algorithm greatly reduce the number of plate recognitions, and is more feasible
and reliable for ETC enforcement. This will activate some consequent activities against the violation vehicles.
Keyword—ETC, multilane free flow, violation enforcement, bipartite graph, matching.
Guo-Huang Hsu received the BS degree in electronic engineering from National United University, Taiwan, Republic of China, in 2002, andthe MS and PhD degrees in computer and information science from National Chiao Tung University, Taiwan, Republic of China, in 2004
and 2009, respectively. He is currently an engineer in the Information and Communication Research Laboratories of Industrial Technology
Research Institute. His research interests include telematics, interconnection networks, analysis algorithms, and graph theory.

Liang-Rui Lin received the BS degree in Department of Computer Science and Information Engineering from National Taiwan Normal
University, Taiwan, Republic of China, in 2009 and the MS degree in computer and information science from National Chiao Tung
University, Taiwan, Republic of China, in 2011, respectively. He is currently an assistant Clerk in Data Communications Business Group ofChunghwa Telecom.

Rong-Hong Jan received the B.S. and M.S. degrees in Industrial Engineering, and the Ph.D. degree in Computer Science from National
TsingHua University, Hsinchu, Taiwan, in 1979, 1983, and 1987, respectively. He joined the Department of Computer Science, National
Chiao Tung University, in 1987, where he is currently a Professor. During 1991-1992, he was a Visiting Associate Professor in theDepartment of Computer Science, University of Maryland, College Park, MD. His research interests include wireless networks, mobilecomputing, distributed systems, network security, and network reliability.

Chien Chen received his B.S degree in Computer Engineering from National Chiao Tung University in 1982 and the M.S. and Ph.D. degrees
in Computer Engineering from University of Southern California and Stevens Institute of Technologies in 1990 and 1996. Dr Chen hold aChief Architect and Director of Switch Architecture position in Terapower Inc., which is a terabit switching fabric SoC startup in San Jose,
before joining National Chiao Tung University as an Assistant Professor in August 2002. Prior to joining Terapower Inc., he is a key member
in Coree Network, responsible for a next-generation IP/MPLS switch architecture design. He joined Lucent Technologies, Bell Labs, NJ, in1996 as a Member of Technical Staff, where he led the research in the area of ATM/IP switch fabric design, traffic management, and trafficengineering. His current research interests include vehicular ad-hoc networks, content-centric networks, and cloud computing.