Re: Pontoon Bridge on SG on RYPN

The Milwaukee is the only road I know of that ever used them, all standard gauge. There was the one at Marquette, IA (actually a dual pontoon span, as there were two channels to cross before the lock and dam system), one at Wabasha, MN, and one across the Missouri at Chamberlain, SD. Fascinating structures, though. Having grown up only a few hours from the batch on the Mississippi, I always wished I'd been around to see one.

They were all rather tinker toy assemblies, fragile and requiring massive amounts of manpower to keep operating. Water level changes were accomodated with work crews constantly adjusting the track level on the pontoon using jacks and blocks. The pontoons only lasted about a decade before needing replacement. Ice caused damage nearly every year because of the large side surface area.

There's a webpage on the Wabasha bridge that shows the short slip apron onto the pontoon about halfway down the page. I wouldn't want to take something across it...