OP
paintman161
Silver Member
As for the steel girders, clean the dirt away from the ends and don't worry about them. They'll still be there and plenty strong in 100 years.
For the decking on top, if you plan to run boards length wise as a top layer, I wouldn't be putting the 8x8 that close together unless you only run the lengthwise boards on the tire track areas. If you fully deck the top with 2x or thicker lumber, if it were mine, I'd leave a 12" or so between the 8x8s. Only leaving 3/4" of an inch will certainly make for a stronger bridge but will also be way overbuilt than need be for a CUT and foot traffic.
The shim idea mentioned above, while a neat idea, to me seems like WAY more work than what it's worth. If you are concerned about water sitting on the deck boards, make sure you install them with the grain of the wood like a U (look at the end grain) When wood dries, the growth rings try to straighten out giving a slight crown on the top of the board shedding the water. If you install them with the grain like an upside down U, they may dry to hold water, but not much.
If you run one of the 8x8 extra long every 6 or 8 feet sticking a couple feet out each side it will allow for bracing of sides/handrails without impacting traffic on the bridge
Thank you for the idea, gotta keep cost down some too. Your idea makes sense and yes i did plan on running either the 8x8 longer every few feet or just a 2x8 longer for support for the railing.