Filling Traffic Detection Gaps on HOV Lanes

A California law allowing selected single-driver, electric-hybrid vehicles to use High-Occupancy Vehicle (HOV) lanes places an additional burden on crowded sections of HOV lanes. This burden potentially degrades lane performance and limits the incentive to carpool.

In fact, the Federal Highway Administration mandates that hybrids not clutter HOV lanes past a set level and requires monitoring speed and traffic flow in HOV lanes. Such monitoring is typically performed by traffic sensors, usually inductive loop detectors. However, long stretches of HOV lanes on California freeways are not equipped with detectors, or are equipped with deficient detectors.

CCIT, with sponsorship from Caltrans, has designed optimal methods to fill the gaps in current HOV-lane monitoring systems. Emerging sensor technology is cheaper and faster to deploy than traditional inductive loop technology. For instance, wireless sensors by Sensys Networks, of Berkeley, CA, collect traffic data of comparable accuracy to that collected by inductive loops, at less than half the life-cycle cost. These sensors take three to four times less installation time, requiring fewer and shorter lane closures.

These capabilities were demonstrated via a pilot deployment at two locations on US-50, and CCIT plans to conduct a pilot demonstration at two more locations on I-80. These tests were deployed in partnership with Caltrans District 3 (Sacramento).

The team also conducted a comprehensive review of detection gaps on HOV lanes in Districts 3 and 4, and drafted deployment scenarios to increase the number of monitoring stations on those corridors.