I know it's a long shot, but if you ever find yourself near Williamsport, PA, check out the Arch St bridge - http://bridgehunter.com/pa/lycoming/412064001000000/
It's an open grate bridge, so I wouldn't recommend riding it. Crossing on foot can even be interesting, as the bridge bounces quite a bit with traffic. It's in poor condition, but still used heavily.
1967 Yamaha YDS3 250cc smoker - project of the decade
1981 Yamaha XS850S Triple! - current project
1981 Suzuki GS450 - coming soon!