What is Ramp Metering?
Ramp metering is the use of a traffic signal(s) deployed on a ramp to control the rate at which vehicles enter a freeway facility. By controlling the rate at which vehicles are allowed to enter a freeway, the flow of traffic onto the freeway facility becomes more consistent, smoothing the flow of traffic on the mainline and allowing more efficient use of existing freeway capacity. Ramp metering can be an effective tool to address congestion and safety concerns that occur at a specific point or along a stretch of freeway. Ramp metering can also improve overall system performance by increasing average freeway throughput and travel speed, and decreasing travel delay. Finally, ramp metering can lead to a reduction in fuel consumption and vehicle emissions. Specific benefits documented in past literature are described in Chapter 5 of the Ramp Management and Control Handbook.
