GOVERNMENT TECHNOLOGY/Improving commutes with ITS
Many cities and counties benefit from applying information and telecommunication technologies to their transportation issues and challenges. Known collectively as Intelligent Transportation Systems (ITS), the technologies can save time, money and lives in urban and rural areas.
For many communities, the development of ITS begins with the design and installation of an advanced traffic signal control system, which continuously adapts to changes in traffic flow and coordinates signal timings from one intersection to another. Traffic sensors and a telecommunications network provide traffic data to a central traffic management center, where computers and technical staff monitor and manage the traffic signals on an area-wide or regional basis.
The Split Cycle Offset Optimization Technique (SCOOT) and the Sydney Coordinated Adaptive Traffic System (SCATS) are two adaptive signal control systems used in the United States. Unlike typical traffic control systems that use fixed coordination timing plans, which are programmed according to common traffic patterns at different times of the day, adaptive control systems continuously adapt to traffic patterns to optimize traffic flow.
Adaptive signal control systems have been used for approximately 20 years, and communities have found that they reduce travel times for residents by providing shorter queue lengths and fewer stops. Communities also have found that the systems help squeeze more capacity from existing roadway and highway infrastructure by allowing more vehicles to move through the network.
Advanced traffic signal control systems also save cities and counties money by eliminating the task of re-timing traffic signals every six months. Because the systems automatically calculate and apply the right signal timings for traffic conditions, the signals always are well-timed.
“In practice, few agencies have the resources to update their signal timings regularly,” says Peter Martin, director for the Traffic Lab at the University of Utah. “Research has shown that under stable conditions, timings age at a compounding annual rate of 3 percent.”
While adaptive signal control systems are beneficial on their own, they can be combined with other technologies to improve commutes for residents. The sensors in the roads that provide traffic data to the signal control system can generate and deliver information, such as travel times and congestion alerts. Data from surface streets can be combined with data from freeways and expressways to coordinate urban surface street, arterial and limited access highway management. Add data about the local transit system, and cities and counties can create a multi-modal transportation management and information system that can help balance the use of cars and transit, while improving the traveling experience for a greater portion of the population.
By planning ahead and providing enough capacity in the telecommunications network, cities and counties can add CCTV surveillance cameras for incident detection along roads. The network also allows transportation managers to operate roadside dynamic message signs that provide drivers with information on the status of the highway network.
The traveler information system helps residents make the best use of the transportation services and facilities in the community. Additionally, ITS can help local officials respond to a natural or man-made emergency, such as a hurricane or terrorist act. By equipping transportation networks with technology, cities and counties can control traffic problems and make informed choices about transportation alternatives.
The author is vice president and ITS Division Manager for Miami-based PBS&J.
