Q. What is the peak hour (or 15 minute) capacity of a 12-foot wide pedestrian bridge, 175-feet long?  Our Parks Department is designing a bridge over a canal next to a new cultural center that could generate large numbers during events and want some assurance that 12-feet will be wide enough.

David Henderson
Miami-Dade MPO

A. Hi David.
I don’t have anything as technical as that. But, when we improved an old car bridge near our university, we went for the full width between the structural members (18ft). We had done a count before the structure was improved and came up with about 1200 people (bicyclists and pedestrians) in 12 hours on a spring day during school. At that time, the usable width was about 8 ft with 3 ft entrances on either end and was in a sorry condition. It was very helpful to have an existing structure there at the time, to give us some sense of typical use.

 

The improved structure could safely hold people standing shoulder to shoulder all the way across (according to the county bridge engineer). However, our real width considerations were more to do with whether pedestrians could stop and talk leaning on the railing and looking down at the river, and bicyclists could ride side-by-side while chatting. In other words, we looked at the bridge as a place. And a people mover.

 

I think that taking that use into consideration also allowed it to serve folks going to a special event, e.g., football games, concerts (the Stones came last fall and many folks used the bike/ped bridge).  If you’re going to get large amounts of event traffic, I’d push for more than 12ft. If you’ve got a couple of people leaning over the railing, watching the river (or whatever), and a bicyclist coming each way, it’s a little bit uncomfortable. We’ve got a couple of 14-ft bridges (with bulb-outs for folks who want to hang out, fish, etc). I got the idea from a bike/ped bridge on a trail near Sacramento and liked it.

Cheers!
J

PS: Here’s a bike/ped rail yard overpass we got done in the mid-90s.I believe it’s 18ft wide. It’s got bulb-outs, too.
http://www.bikeplan.com/project1.htm

 

Here’s a newish bike/ped bridge. I believe it’s 14ft wide (not close to the U or other major traffic generators but is part of the river-front trail system). You can’t see the bulb outs but they’re at the middle on both sides.
http://www.bikeplan.com/project2.htm