The Maryland State Highway Administration Statewide Operations Center (SOC) needed to develop an overall strategy for the enhancement of their communications system. The original decentralized network of DTMF, leased 56 KBPS dedicated, and T1 telephone lines developed over a period of years in an incremental fashion as various pieces of traffic control and monitoring equipment were installed. A resource sharing agreement between the State of Maryland and MCI Telecommunications created a fiber "backbone", and gave Maryland engineers controlled access to the utilities' fiber trunk line from the Maryland/Pennsylvania border, down the entire length of I-95, to the Capital Beltway, including a fiber "spur" to Maryland's SOC. This public/private partnership provided a vehicle for testing alternative image transmission technologies, utilizing the direct fiber connection to the SOC. Frequency division multiplexing (FDM) was one such alternative, and was, in fact, used as a test demonstration to bring pictures back from several camera sites along the Baltimore Beltway to the SOC for its inauguration. As a demonstration project, two CCTV sites along I-95 were connected to the fiber "backbone", and the images transported back to the SOC using the same brand FDM equipment used during the inauguration of the SOC. The images were displayed on the monitors, along with the compressed images. Feedback was obtained from the operators, as well as members of the SOC management team. After several months of viewing the images, it was decided that in the absence of unlimited bandwidth, image quality was of secondary concern in a traffic monitoring environment. The full-motion video was beneficial when the cameras are zoomed down onto an accident scene, but it was not necessary most of the time when the cameras are being used to monitor a highway section in general. (A*)
Samenvatting