The Mt. Pleasant Planning Commission's discussions about improvements to Mission Street have, once again, brought out well-meaning questions asking why the Michigan Department of Transportation doesn't just build some pedestrian bridges over the busy roadway.
The reason: They won't work. They would be a gigantic waste of money.
Here's why: In real life, most pedestrians, confronted with stairs, long ramps, switchbacks or even elevators to a pedestrian bridge, would choose to take their chances in traffic.
The Americans with Disabilities Act would require the construction of a pedestrian bridge with either a long ramp or an elevator.
The recommended slope for a public access ramp is 1:12, meaning 12 feet of ramp for each 1 foot of rise.
A pedestrian bridge's deck would likely be about 18 feet above the road, giving 15 feet for truck clearance and 3 feet for trusses supporting the bridge. That would require ramps 216 feet long on either side of the bridge.
How much is that? It's roughly the distance between Washington and Main streets - a city block.
Few people would walk two blocks out of their way - and climb - just for safety's sake. People, especially young people, judge real risks very poorly.
Take a look at a full explanation, with pictures, at pedestrian.org.
Any Mission Street pedestrian bridge would be a lot like the crossing pictured in Maryland - expensive, with the pedestrians running through traffic in the shadow of the bridge.