Well, Mayor Rahm Emanuel only promised one: 100 miles of protected bike lanes. But as I pointed out on Friday, July 22, 2011, there are 25 bridges that are still hostile to cycling.

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If you can see the water below, you’re on an open metal grate bridge. But don’t look down as you may lose your balance.

Let’s say that Emanuel and Department of Transportation (CDOT) commissioner Gabe Klein finally read that study the department conducted in 2004 and pledged to fix them.

And let’s say they offered this:

25 miles for 25 bridges. Instead of building 100 miles of protected bike lanes in the mayor’s four-year first term, his administration would only build 75 miles, but add bike-friendly decks to 25 bridges.

Would you take that deal?

Comparing costs

We know that the bridge plates cost $30,000 plus installation. And the half-mile Kinzie Street protected bike lane (in both directions) cost $140,000. So it seems bike-friendly bridge decks are cheaper than protected bike lanes* – most of the other bridges are longer than Kinzie and will cost more. The study does note the distances and portion of each bridge deck made of metal grates.

Another method of bike-friendly decking is filling the grates in with concrete, like you see on Randolph and Harrison Streets. This may be a more complicated installation because the bridge has to be able to accommodate the extra weight.

The next step

The City likely won’t offer that deal. If citizen cyclists want bike-friendly bridges, they’re going to have to raise a ruckus. “The squeaky wheel gets the grease.” The first thing you should do is find out who your alderman is.

Cross-posted to Moving Design. Read more policy insights from Steven Vance.

*What should be determined is the effectiveness of each facility change on the number of crashes reduced (or increase in the feeling of safety), or the change in the number of people bicycling here.