Have any of you ever built a cattleguard? I hate having to open and close the gate across my driveway (and my GF can just barely do it). But the range cows seem to have some sort of psychic sense that brings them in from miles around if I ever leave the gate open.

It'd have to take the weight of the propane truck, and not injure any cows - Their owner is a bit of a SOB, and I'd hate to have to buy one of his critters.

I've thought about just leveling out the area and laying some 4x4s on the ground with a 2" or so gap between them and nailing a couple of 2x4s perpendicular across the tops to keep them from moving around. Any thoughts?