JACKSON, Miss. (AP) — The Mississippi Department of Transportation aims to unstop one of the state's worst traffic bottlenecks.

The state Transportation Commission is contracting with Key LLC of Madison for $12.3 million to widen a bridge on northbound Interstate 55 at Interstate 220 in southern Madison County.

I-55 narrows to two lanes at the bridge, causing a miles-long traffic slowdown for northbound commuters most weekday afternoons.

Transportation Department spokesman Jason Scott says the state will remove railings and widen the bridge to three lanes. He says the state won't have to demolish a flyover to Interstate 220 supported by pillars flanking the I-55 bridge.

The project also includes repaving a short stretch of I-55 and part of Old Agency Road in Ridgeland. Scott says work will start this fall with repaving Old Agency.