Drivers can soon leave that 55-mph speed limit along the top end of I-285 in their rearview mirror.
Starting in September, the maximum speed limit along 36 miles of the Perimeter within Fulton, Cobb and DeKalb counties will be raised to 65 mph, matching a speed limit increase that took effect Nov. 1 on the south end of the Perimeter.
But don’t celebrate just yet. During times of heavy congestion, accidents or severe weather, the Georgia Department of Transportation will begin using new overhead electronic messaging signs to slow traffic speeds in 10 mph increments — to as low as 35 mph.
State transportation officials acknowledge most drivers already travel well in excess of 55 mph on I-285 when conditions are normal.
“This is not about speed-trapping anybody,” said Karlene Barron, a spokeswoman for the Georgia Department of Transportation. “This is actually the opposite. We are trying to get people closer to the level they are actually going when conditions are safe enough for them to go that speed.”
GDOT will be able to reduce the speed limit in real time, when workers monitoring conditions on cameras in its Transportation Management Center decide conditions merit it.
Research in other cities that have variable speed limit systems (such as Orlando, Seattle and St. Louis) has shown they reduce stop-and-go traffic by allowing cars to travel at slower, more consistent speeds. This in turn helps reduce rear-end and lane-change wrecks associated with sudden stops at the back of congested areas, according to GDOT.
The technology is only being deployed along the top end of the Perimeter right now because it carries more traffic and has nearly twice as many interchanges. More traffic and more interchanges cause more weaving, merging and congestion and a greater risk of crashes.
It’s possible that other interstates or the south end of I-285 may get the same treatment in the future. But Barron said the department intends to wait and see how the variable speed limit works on the north end first.
Preliminary construction has already begun on the sign structure and will continue through July. There will be a 30-day test of the signs in August before the variable speed limit system takes effect in September.
About the Author
