Most standard MDFCTA troughs are either 4ft, 6ft 6in, 9ft 6in or 18ft long. However, I have found a few exceptions. This page only includes troughs that are definitely, or possibly, MDFCTA structures - many troughs that I've classified as a non-MDFCTA structure are of a non-standard size.
Southfleet (moved to New Barn)