Best Practice

BEST PRACTICE:

J1−2: Mobile Surveillance/Ramp Metering

DESCRIPTION:

This practice features self−powered mobile surveillance trailers with various off−the−shelf technologies such as wireless communication infrastructure operating in several unlicensed frequencies (spread spectrum), and video image processing. This technology is able to provide images and traffic data (speed, volume, occupancy) to the traffic management center (TMC) from locations that do not have permanent surveillance infrastructure (e.g., sensors, loops, CCTV) or have had it interrupted during road work. The trailers can be used to control ramp meters that have had their normal capabilities disabled and can keep them in communication with the TMC.

REASON(S) FOR ADOPTING:

The reason for exploring this method of traffic surveillance is in some instances during construction, surveillance for essential links in the freeway system or in the city street network may be disrupted. If no existing surveillance infrastructure existed before construction began and considerable traffic disruption is expected, this method would allow for collection of information that can be used to detour or inform the traveling public by activating variable message signs. During an event management scenario (Super Bowl, large conventions, or the State Fair), the trailers can be helpful in managing traffic.

PRIMARY BENEFIT(S):

This practice will allow the collection of traffic data (speed, volume, occupancy) and the transmittal of video images while the existing surveillance infrastructure is inoperable (due to construction, maintenance, etc.) or if there is no existing infrastructure. Freeway ramp meters will be running in normal mode and will remain in communication with the TMC although their sensors and loops may not be operating.

MOST APPLICABLE LOCATION(S)/PROJECT(S):

This method of collecting data can be used on freeways and city streets, in urban areas and rural areas, in a variety of construction activity.

STATE(S) WHERE USED:

California

SOURCE/CONTACT(S):

Ed Khosravi, Senior Transportation Engineer, Caltrans, District 11
Phone: (714) 724−2453
E−mail: ed_khosravi@dot.ca.gov