Finished culvert
Once the concrete dries, simply slide the airform out to be used again and again. The dirt can be backfilled in a few days, and you have a simple, permanent, culvert.
Image from Airformed Culverts story
Once the concrete dries, simply slide the airform out to be used again and again. The dirt can be backfilled in a few days, and you have a simple, permanent, culvert.