On Thursday, VDOT unveiled new electronic speed limit signs that can display different numbers depending on road conditions on a 15-mile stretch of Interstate 95. The limits displayed on the signs will be anywhere from 70 mph down to 35 mph.
Twenty-four pairs of signs are now in place on northbound I-95 from near mile marker 115 in Caroline County to Route 3 in Fredericksburg. VDOT said that section of I-95 experiences major congestion, especially on weekends when people from the D.C. area return from trips.
Kelly Hannon, the spokesperson for the VDOT Fredericksburg District, said the point of the signs is to “gradually step down the speed limit to slow traffic before [traffic] reaches the point of congestion.”
She said sensors that detect vehicles on I-95 feed information to a computer that uses an algorithm to decide when to slow speed limits down and when to increase them.
VDOT believes the benefits will be two-fold. Hannon said the new signs should make the interstate safer by reducing rear-end crashes--55% of crashes on that stretch from 2015 to 2019 were rear-ended crashes that often happen when traffic suddenly stops. And they should also decrease the severity of traffic jams by preventing some stop and go situations.
In addition to the electronic signs that can display different speed limits, Hannon said both old and new message board will be used to explain why speed limits are lower at times.
“Maybe it’s a crash, it could just be congestion, or maybe we have a lane closed for a work zone,” she explained.
Hannon said other parts of the country have successfully installed variable speed limit signs and if, as VDOT expects, they are a success on I-95, VDOT will explore other areas to install them besides the 15-mile stretch of I-95 North.
In the D.C. region, it appears the only other roads that have such signs are express lanes such as I-95.
However, there are two other areas in Virginia that have them: Interstate 77 at Fancy Gap in Carroll County--where they are used to slow down traffic if fog suddenly rolls in-- and in the Hampton Roads area in the Hampton Roads Bridge-Tunnel and on the Monitor Merrimac Memorial Bridge-Tunnel. Nowhere else in Virginia are they on a free road for as long a stretch as they are on I-95.
Other metro areas that use them include Seattle, Las Vegas, and San Francisco.