Design And Implement Of The ETC Roadway Data Exchange Subsystem

The ETC (Electronic Toll Collection) system achieves the wireless communication between the vehicles and the toll gate by the automatic vehicle identification technology, which realizes the automatic toll collection without car stopping, and therefore relieves the traffic jam problem effectively. Because it involves the toll collection problem, the correctness of the ETC transaction data is very important, and ensuring its security and reliability is also the basic requirement of the national highway toll collection standard. Depending on the function requirements of the roadway software of the Chongqing ETC system, this paper realizes the ETC data's exchange between the local database and the toll gate business logic control subsystem, and also the databases between the toll gate client side and the toll station server side. Depending on the methods of the data's exchange, the data exchange subsystem can be separated into the information management and the data transfer two modules.The information management module wraps the operations on the local database, and also provides the API functions for the control subsystem of the roadway software, which makes the upper logic much easier. The information management module mainly realizes the records querying, records saving and toll calculation three functions. Each function module's realization has been optimized by its own data's features, and they all have the characteristics of high performance, failover and stability.The data transfer module realizes the network transmission of the ETC data between the client side and the server side, and runs at the background as the daemon threads of the ETC system. The data transfer module mainly realizes the data download; data upload and time synchronization three functions. The data download function is realized using the middle database method, which has the characteristics of real time and high reliability. The data upload and time synchronization functions are realized using the network communication method under the C/S mode architecture, which ensures the reliability during the network delivery process of the ETC records, and also control the load at the server side effectively.This paper gives the architecture design of the data exchange subsysterm, the detail design and the optimization strategy of each function module. This data exchange subsystem has been used in the roadway software of the Chongqing ETC system, and also has passed the lab test phase and the field test phase, the system runs steadily and achieves good results.