Network-Enabled Electronic Toll Collection and Surveillance System Electronic Toll Collection systems are becoming an increasingly popular way to both speed up toll collection and to monitor driving patterns, traffic movement, and congestion problems. As shown in the diagram above, the typical system consists of a transponder or "smart tag" located in the vehicle that is accessed by a tag reader (located on an overhead archway) that is connected to one port of Quatech's DSE-400D device server. The vehicle is tracked at the toll entry point, and a flat toll is immediately assessed, or if a variable usage toll is employed, a second smart tag reader at the exit will access the smart tag and assess the appropriate fee. This dual point system can also be used to track traffic patterns, measure the average travel time between two toll points to indicate traffic slowdowns or potential accident sites. To prevent "toll-skipping" cameras are typically co-located with smart tag readers in order to photograph drivers attempting to pass without paying. These images can be relayed to upstream patrol cars, or can be recorded for subsequent prosecution. While a fixed camera is acceptable for many systems, the ability to control the positioning of the camera is a useful addition. Using the second port on the DSE-400D as an RS-422 interface, Pan-Tilt-Zoom control of these cameras is easily accomplished via remote control.

With device servers, the remote serial equipment can be network-enabled using the fiber LAN network already in place along most major roadways. The devices can then be accessed by any authorized PC or server on the network, regardless of operating system, just as if it were directly attached to a local COM port. And, while only one computer at a time can access a particular port, multiple computers running different operating systems can access different ports on the device server simultaneously--thus the toll collection agency can be constantly polling the tag reader using a Windows system at the same time a police agency running a Linux system accesses the camera PTZ controls.

Quatech device servers are particularly well suited for this electronic toll collection system because they offer the industry's lowest latency. Particularly in heavy traffic locations, electronic toll collection is a polling-intensive application. Quatech's high performance device servers in ultra low latency mode offer the speed and reliability required to keep electronic toll collection systems functioning flawlessly.

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