Building a Driveway Bridge

[erwinpaul]

I am spanning a creek that is separated by an island. the driveway going across is only 10' wide made possible by the ten foot culvert pipes. it is filled and graveled level, but I wish to build a bridge structure for the weight and width of the concrete trucks. I have 25 feet of distance to cover, and already have about 70 pieces of 4x6 pressure treated that are 12 feet long, and these will run side to side on the bridge. I am wondering what I can attach these to, whether it can be a couple of utility poles stretching across or if I can get by with 6x6 pressure treated stock. the area is level and they will lay flat, but I wanted a little wider (hence the 12' 4x6's) and looking cool too. can this hold up to a concrete truck or dump truck?

[Mr T]

25' is quite a long distance to cover. This is something you are going to want to get a engineer out for.

For starters utility poles are not strong in the way you want to use them. They are used for a compression type weight (such as supporting wires, ect) Ever seen what a car can do to one? They are intended to break easily if hit/flexed/sheered.

If your bridge doesnt hold when a concrete truck goves over it, I'm sure the owner of it will be talking to you about paying for damages caused+ the wasted load of concrete. Your insurance company will look at it too, and if it was not a safe/proper/inspected design, they may deny any claims on it. Concrete trucks are not cheap.

If your house catches fire, the last thing you want happening is the fire dept stopped at the base of the bridge debating if they want to risk crossing it or not....or what they are going to do next, if the bridge doesnt hold their weight... Meanwhile your house is burning down.

[erwinpaul]

Maybe I should clarify. it is not a working bridge in the sense that it will span a void, rather it is mainly for decorative purposes on an already existing roadway. However with that in mind I do not want it to go crack everytime someone drives on it. I am planning on forming a beam of three layers of 4x6 stock, and bolting the remaining 4x6's across that. I just wanted something more comfortable than the 9 foot wide driveway that went over the culvert pipes