The now-unclassified former B904 in Old Polmont
The B904 was a short link road to the east of Falkirk.
It started on the A9 (now A803) in Polmont and headed north along Bo'ness Road before bearing right onto Smiddy Brae. It zigzagged to cross the River Avon at a narrow bridge before continuing east to end on the A904.
The road survived until the 1970s, gaining a bridge where it crossed the M9, but no longer exists. Most of the road is now unclassified but the easternmost section - beyond the Avon bridge - is now part of the A905.