Two major problems influenced the Idaho Transportation Department’s design of the recently completed intersection of U.S. Highway 12 and 21st Street in Lewiston.

One of the most common traffic moves at the busy junction came from vehicles — especially heavy trucks — turning left onto East Main Street when coming off Memorial Bridge. Traffic backed up onto the bridge during busy times since there was no signal, and vehicles had to wait in an ever-growing queue for a chance to zoom through a gap in oncoming traffic to make the turn, according to project manager Curtis Arnzen. Double left-turn lanes at every signal should alleviate that problem.

The old design also had an unorthodox five legs, which created more potential points of conflict between vehicles and pedestrians. The new design reduces the number of conflict points by eliminating one of those legs to create a simplified, more traditional intersection.

The $7.5 million project also features other pedestrian safety improvements and better infrastructure under the roadway to drain the torrent of stormwater that can hit the intersection during major rain events. And eastbound motorists on Main Street can now turn right onto southbound 21st Street. They previously had to use 18th Street to get to G or Idaho streets, and then to 21st.

— Joel Mills, of the Tribune

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