Variable Speed Limits – Telegraph Road to Springfield Interchange


For those of you that travel in the Woodrow Wilson bridge corridor, you may have noticed electronic speed limit signs as well as other electronic signs going up in this corridor. After 18 months of study, a variable speed limit system will be set up on the Capital Beltway between the Springfield Interchange and the Telegraph Road Interchange. It will be turned on in late July.

Sensors and cameras will monitor traffic flow, then alert an operator in a control center to adjust speed limits to allow for better flow through the area. The basic concept is to slow traffic down so that drivers avoid hitting the same congestion all at once. By doing that, it allows for a ‘smoother’ ride through the affected area.

This is the same type of concept used in the “ramp metering” systems, which are used in the D.C. region. Those devices have red and green traffic lights on ramps to highways, and only allow a certain number of cars to enter a freeway at a time.

Initially, the variable speed limit system will only be used during overnight construction periods near the Wilson Bridge, when there are lane reductions. However, there is the potential for the system to expand full time. If that happens, the system will be turned on 24 hours a day, constantly updating the speed limit to allow for a better flow to and from the bridge.

There will be a VIGOROUS police enforcement of the new system. State Police will be on hand to make sure drivers obey the changing speed limits. Initially, the police will be issuing warnings and after a week those warnings will turn into stiff fines.

The highest the speed limit will go is 50 mph, the lowest it could go is 35 mph. The system also will tell drivers how long they have before they reach a certain point. For example, a driver getting on the Beltway at the Springfield Interchange may be told it will take 15 minutes to reach the Wilson Bridge.

Transportation officials from the Wilson Bridge project are looking for ways to cut down on the number of fender benders and accidents near the bridge. Those incidents ultimately lead to hours of delays. The hope is that the variable speed limit system will reduce the number of collisions by keeping traffic flowing at an even keel.

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