Ramp Management and Metering
Managing traffic on freeway entrance and exit ramps, or ramp management, is the "application of control devices, such as traffic signals, signing, and gates to regulate the number of vehicles entering or leaving the freeway, in order to achieve operational objectives". Most ramp management strategies are employed to balance freeway demand and capacity, maintain optimum freeway operation by reducing incidents that produce traffic delays, improve safety on adjacent freeways or arterial streets, or give special treatment to a specific class of vehicles.
Ramp management strategies and the systems that support them are often implemented in conjunction with other freeway management programs to create operational efficiencies and assist in the delivery of overall transportation management goals and objectives. Ramp management goals, objectives, and the strategies to achieve them should be consistent with regional transportation goals and objectives and must support the mission and vision of the operating agency. Ramp management goals, objectives and strategies should be defined at the regional level and should fit into the context of the broader transportation planning process including the freeway management program.
The selection and implementation of ramp management strategies must be based on needs. The existing needs must be appropriate in order for ramp management to be effective and to justify the investment in these strategies. Ramp management strategies may be used to control access to selected ramps, thus limiting the periods when vehicles may access the ramp or possibly restricting access to the ramp permanently. This significantly reduces, or may even eliminate, the potential for collisions that occur as a result of traffic entering or exiting the ramp facility and in turn smoothes the flow of traffic on segments of roadway where these collisions have occurred in the past.
Ramp management may also control the manner in which vehicles enter a freeway. For instance, vehicles that enter the freeway in platoons introduce turbulence into the freeway system, which causes vehicles on both the mainline and ramp to slow down to safely merge. This causes congestion around and upstream of ramp/freeway merge points. Ramp management strategies may be used to control the flow of vehicles entering a freeway, thus smoothing the rate at which vehicles are allowed to enter the freeway.
Why Is Ramp Management Important?
Ramp Management can offset congestion and safety problems that compromise efficient and safe traffic operations on ramps and or on the facilities to which they connect. In doing so, ramp management helps achieve greater return on investment for transportation infrastructure projects and contributes to the realization of pre-determined goals and objectives. Ramp management also serves as an effective medium through which different agencies can collaborate to address needs more effectively. Since ramps often join facilities that are operated by different agencies, ramp management can break down barriers that exist between agencies, allowing these agencies to work together to more effectively address issues. For instance, a state agency such as the Department of Transportation (DOT) may operate a freeway including adjacent ramps, whereas a local agency such as a city engineering department may be responsible for operating the street or arterial that runs parallel to and connects with the freeway. Using ramp management strategies and techniques, the state and local agency can work together to address traffic problems near the ramp, while remaining cognizant of each other’s concerns.
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United States Department of Transportation - Federal Highway Administration