Transportation Surveillance Goes Digital
While preparing for the 2002 Winter Olympics in Salt Lake City, the Utah Department of Transportation (UDOT) used its traffic surveillance system to provide video feeds to local, state and federal security personnel. The idea worked so well that UDOT is managing current upgrades to the system with an eye to security and emergency management.
Like many state departments of transportation around the country, UDOT has traditionally used CCTV surveillance to monitor traffic and to coordinate local and state responses to traffic incidents. Utah’s current system monitors state roads, freeways and some surface streets in the Salt Lake region with 265 analog video surveillance cameras. “We are gradually pushing cameras out from Salt Lake to the rest of the state,” says Sam Sherman, a transportation systems engineer with UDOT.
A state-owned fiber-optic intranet carries camera video from the field back to UDOT’s Salt Lake-based Traffic operations center. The intranet also connects traffic management technology such as traffic lights to the operations center.
At the operations center, the fiber cable feeds the video into a matrix switcher, a device that manages video signals from multiple cameras. With a switcher, an operator can direct video from individual cameras to monitors and video recording systems, while adjusting camera views with pan-tilt-zoom (PTZ) controls. When first installed in the mid-1990s, the UDOT switcher formed the heart of a state-of-the-art intelligent transportation system (ITS) for traffic management.
By 2003, UDOT decided to convert the system from analog to digital technology, a move that will eventually eliminate the switcher. “Digital video technology will make it easier to expand our CCTV network and to distribute video to more distant locations,” says Michael T. Van Orman, an IT analyst with the DOT who works on the project with Sherman.
UDOT had two options: to replace the existing analog cameras with digital cameras; or convert the analog camera signals to digital data. Since the existing camera network had been specifically designed with Utah’s severe outdoor climate in mind, they decided to leave the cameras in place and convert the video.
UDOT chose VBrick Systems Inc. of Wallingford, Conn., to develop a conversion device to translate 265 analog camera signals to digital. Called the VBrick Security, Surveillance, and Monitoring (VBSSM) appliance, the encoder device is smaller and lighter than a laptop computer and can be mounted near cameras in any location — on telephone poles, bridges, and buildings, as well as in transportation vehicles. Conformal-coated circuit boards make the device practical for harsh environmental conditions.
The encoder accepts analog video in NTSC and PAL — analog video formats used in the United States and Europe, respectively — compresses the video and transmits it digitally over an Ethernet connection to the fiber-optic network.
In June, UDOT began the analog-to-digital conversion. The first step focused on transmission. At the traffic operations center, digital video will be decoded back to analog video and sent through the switcher to the existing monitors.
The current UDOT network includes fiber-optic feeds to analog monitors in other Utah state departments, such as emergency management and the state police. “We’re not ready to open up our intranet to generic PCs, which would mean that individuals we don’t know and cannot control would potentially have access to the system. That’s important because our network is more than an intranet. It is really a private field network that includes traffic control devices as well as cameras.”
In the early stages of the conversion, the new system will increase traffic monitoring capabilities without requiring new fiber-optic cabling. UDOT’s short-term goal is to complete the conversion to digital video transmission before the matrix switcher wears out, which will likely occur within several years. At that point, Sherman and Van Orman will have to buy a new switcher or think about the security issues related to a total digital conversion.
A fully digital system would provide consumer Internet access to cameras showing traffic conditions. Perhaps more important, a digital system with an Internet link will make the system’s video easily available to local, state and federal agencies with emergency response, law enforcement and security responsibilities.