Needing to build a low water bridge over a dry creek. Plan on using two 24” plastic culvert pipe to let water pass under bridge after heavy rain. Plan on installing footer under culvert on upstream side of bridge. Packing 1” minus around culverts and on driveway. Then pouring a concrete slab on top of gravel about 6” thick.This slab would be around 10’ wide & 30-40’ long.
Wondering if it would be easier, less expensive, to work a trench into the creek bed add buttress walls about 6-10 feet apart and then pour a concrete slab over the buttress walls to complete the bridge. Can a concrete slab with only mess & rebar (no I beams) span 6-10 feet and support traffic. The bridge will be in my driveway with normal residential use. That could include some equipment like a concrete truck, truck & trailers with back hoes or maybe a dozer. Thanks in advance for your thoughts and comments.