Quatech Products Used: QSE-400D 4-Port RS-232/422/485 Device Server

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Intelligent Transportation Systems serve many purposes from providing motorists with traffic information via variable message signs, to monitoring traffic flow using remote controlled cameras, to managing that traffic flow using lane control signals. A wide variety of serial devices are used in these systems in addition to those just mentioned, such as pavement sensors that detect traffic volume at lights, loop detector networks used to track traffic movement and radar and sonar vehicle detectors--to name just a few. Traditionally these systems were implemented with PCs located in roadside NEMA enclosure connected to the traffic control devices via serial cables. As shown in the above diagram, a single device server can be used to replace the PC--a significant cost savings. In addition, by using the device server, system performance is significantly enhanced because not only is real-time data available for analysis by the Traffic Management Center, this data can also be disseminated to drivers via message board alerts and via the Internet. In addition, lane control signals, traffic lights, and ramp meters can be used to mitigate congestion.

Thus, network-enabling the serial traffic information system equipment significantly increases its value as a traffic management and control instrument. Further, it enables the system to comply with NTCIP requirements that the devices be available to all authorized jurisdictions, in addition to the Traffic Management Agency that owns the system. 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. For example, as shown in the diagram above, two authorized jurisdictions running Unix and Linux servers can access and control the devices even though the core Traffic Management Server is a Windows-based system. 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.

Other Intelligent Transportation Systems Applications:

• Network-enabled electronic toll collection system
  
  
• Traffic information system (USB)
  
  
• Network-enabled ramp metering system
  
  
• Network-enabled red light camera system
  
  
• Network-enabled remote traffic monitoring system