It's one of an array of ideas that IDOT and the city are mulling as part of yearslong effort to map out elements for a North Lake Shore Drive overhaul. The Drive is more than 80 years old, and its northern stretch needs more than another resurfacing. Bridges need to be rebuilt, pedestrian tunnels need shoring up and backups at busy exit ramps need unclogging. The effort has the right scope, a comprehensive look at making things better for motorists, bus traffic — even runners, walkers and cyclists along the Lakefront Trail.