This is a really interesting product that apparently has been around for a while but is new to me. A ten foot length is $2200.
“Finally, you can have a cattle guard without the inconvenience of having to keep a pit cleaned out. This revolutionary new cattle guard simply needs a level surface for proper installation. There is no maintenance required and the unit is totally portable, to conform with the needs of a modern ranch, farm, oil field or construction company. When driven across, the floor collapses level with the terrain, and upon exiting it begins a slow retrieve, taking 25 to 30 seconds to reach full height. This allows ample time to safely tow a trailer across. Because the floor settles completely against the ground the weight bearing capacity is tremendous. You will never clean a pit again.”
You can get more information at their website by clicking HERE.