TRANSPORTATION OPERATIONS | SIGNALS - SILICON VALLEY SMART CORRIDOR

Project Elements

The major transportation facilities within the corridor are freeways, expressways, surface arterials, bus routes, and LRT lines. The completed corridor will see all facilities instrumented with devices such as traffic detectors, CCTV cameras, and dynamic message signs. The freeways will also have highway advisory radio (HAR) transmitters. A network of traffic detection loops and monitoring cameras will provide real-time data to engineers so that the flow of traffic can be efficiently managed. Changes to signal timing will be instantaneous and will be implemented across jurisdictional boundaries. Up to the minute data will be conveyed to the motorist through highway advisory radio and dynamic message signs so that personal travel decisions can be made to reduce the time a motorist spends on congested roadways. The distribution of data is further enhanced by the partnership with TravInfo, the Bay Area's regional traveler information provider. Traffic data collected by the jurisdictions will be made available to such public/private data clearinghouses for processing; in turn, this data will be provided to motorists via radio broadcasts, phone queries and in-vehicle navigation devices. Effective management of the corridor's transportation network relies on the use of advanced technologies. The project is comprised of the following elements:

CCTV Cameras
Real-time traffic conditions will be visually monitored through the use of CCTV cameras. Cameras installed along the freeway and at critical intersections in the corridor will transmit video images to each agency's traffic operations center (TOC). Visual confirmation of field conditions allows operators to effectively detect and report incidents, and subsequently make any necessary adjustments to the traffic signal system.

Changeable Message Signs
Dynamic or changeable message signs provide motorists with up-to-date messages advising them of major traffic incidents and, in some cases, diversion or alternate route messages. Signs will be installed primarily along the freeway and at selected locations on the surface streets. Displayed messages can be changed remotely from each agency's TOC. By providing motorists with early warning, motorist delay and secondary incidents may be effectively reduced.

HAR (Highway Advisory Radio)
Motorists will have the ability to tune into a designated radio channel to receive real-time traffic reports on conditions that may be affecting the corridor's roadway network. HAR messages consist of warnings, advisories and directions.

Traffic Responsive Signal Timing
Traffic responsive signal timing plans will be activated through the use of vehicle detection devices. Detectors will be installed on local surface streets to gather volume and occupancy data. Coordinated signal timing plans can then automatically be selected across jurisdictional boundaries based on current traffic conditions, instead of changing timing plans only at fixed times of the day. This ensures that the most appropriate timing plan is used even when traffic conditions change unexpectedly.

A fiber optic network will serve as the communication medium through which data and video images will be transmitted between traffic control centers. The fiber optic network will allow for the automated exchange of data and will enable agencies to view each other's cameras when desired.

The data exchange network (DEN) is the critical element that make multi-agency cooperation possible. It consists of a collection of computers linked together to allow for real-time data sharing and exchange between agency control centers. Since each agency has its own unique traffic management system, the DEN translates all data and provides a common interface for all users. The real-time data to be exchanged between agencies will include traffic counts, facility status, incident information, equipment status, planned events, and operational changes.