Managing Managed Lanes

Supporting Technologies and Strategies

Managed lanes require management, which in turn requires the application of advanced technologies and strategies to optimize system operations. Some strategies and technologies have been applied widely, including in northeastern Illinois. Some of the strategies discussed for managed lanes are experimental.

Management of a managed lane facility is usually coordinated through a traffic operations center, which is the nexus of a Transportation communications system linking highway data (sensors indicating volumes and speeds, audio-video feeds, and traffic control device status data) with control features (dispatch of emergency and incident personnel, ramp meter controls, and traveler information provided through expressway variable message signs, broadcast and Web-based information services). A key control strategy for traffic management centers is the detection and quick removal of incidents. Future advancements, through an integrated corridor management system, could integrate freeway and arterials with arterial variable message signs, traffic signal control, and access controls. Integration would facilitate a system-wide response to serious incidents, while likewise facilitating alternative routes through signal and access controls.

A second control strategy employed by traffic operations centers to manage lanes is to smooth the flow of vehicles to prevent incidents and optimize travel speeds. To smooth traffic flow, traffic operations centers can control ramp meters, close access points, and could, with appropriate authority, establish speed and lane control regulations. For example, speed management establishes speed limits or speed guidance in real time to ramp down speeds slowly as traffic approaches slower speeds ahead. Such a system prevents crashes, maximizes throughput, and reduces shock-wave effects of stop-and-go traffic resulting from incidents and bottlenecks.

For dynamic pricing applications, highway information explained above is used to establish the price at which the established performance measure (e.g., maximum hourly volumes and minimum speeds) is maintained and sustainable. The established price is then transmitted to toll notices on the highway, the corridor, and through information services, allowing travelers to make route and mode choices in real time.