Office of Operations
photos of traffic merging onto congested highway, congestion in snowstorm, variable message sign, cargo, variable speed limit sign in a work zone, and a freeway at night
21st Century Operations Using 21st Century Technologies

Traffic Bottlenecks

Combating Bottlenecks


Stopping a ramp queue from backing onto the mainline.

Bottleneck Project: I-70 onto I-695 (Baltimore Beltway). The single lane, eastbound approach off-ramp from I-70 to I-695 often backed up onto, and slowed, the mainline of I-70. The preferred cure would have been to widen the underpass through which this ramp passed, and create a 2-lane off-ramp. However, the cost was daunting because the bridge carried the I-695 mainline. Instead, the upstream ramp was repaved and widened only "up to" the bridge. This provided 2-lanes of storage off the I-70 mainline, which was adequate enough to eliminate the queue backup on (and hence, the delay on) I-70. Meanwhile, the 2-lanes of queued traffic on the off-ramp "self-meter" themselves into one lane under the overpass.