Potholes are formed by water seeping through cracks in the asphalt surface of a road.

BBC: Jetpatchers at work

The other four options include variations on replacing the road surface with asphalt, raising the kerbs, the installation of guard rails and the restoration of two lanes of traffic each way.

BBC: Blackpool Council seeks to reverse prom revamp

"They've got a run of asphalt that's coming out of the surface and, also, I did notice at least one pothole in the main wheel track of the road as well, which is surprising for a motorway surface, " Mr Bullock said.

BBC: Condition of M5 near Bridgwater raises concerns

"When you replace soil and grass with concrete and asphalt, you alter the balance of energy that occurs at the earth's surface, " says Dr. Robert Bornstein, a professor of meteorology at San Jose State University in California.

CNN: In-Depth Specials - City Limits