The B5320 comprises the pre-bypass route of the A57 through the Lancashire town of Irlam. It gained its number following the opening of the bypass in the 1990s.
The road starts at a roundabout on the A57 at the northern end of the bypass and heads south along Liverpool Road, which becomes residential almost immediately. We run through the town centre but the street name does not change. After passing Prince's Park the B5311 bears left at traffic lights, after which we continue through the centre of Lower Irlam and go under the Manchester to Warrington railway line adjacent to Irlam station.
The road continues into Cadishead and ends at traffic lights; the only other classified road here is the B5471, which heads left to return to the bypass. Some road signs claim that the road ahead, under a dismantled railway line and back to the A57 at the southern end of the bypass, is also part of the B5320 but maps disagree.