|From:||Montford Bridge (SJ425157)|
|Length:||17.9 miles (28.8 km)|
|Meets:||A5, B4473, A458, B4386, A488, A5112, A5191, A458, A5, A5064, B5061, B4394, A458, A4169|
|Old route now:||B4373, A4169|
|Route outline (key)|
The B4380 is a route in mid-Shropshire which has shifted westward over time.
Today it starts on the A5 at Montford Bridge, to the west of Shrewsbury and heads east, bypassing the town centre to the south via Meole Brace. After crossing the A5 it goes over the River Severn at Atcham, then TOTSOs right to pass Wroxeter. At Eaton Constantine, the B4380 throws out a short branch to Cressage on the A458, after which the mainline to end at a TOTSO on the A4169 at Buildwas.
The western end of the present route, from Montford Bridge to the gates of Attingham Deer Park, between Atcham and Viroconium Roman city, was once part of the A5 (explaining the TOTSO at the original western end of the B4380). A large proportion of this is the 1930s Shrewsbury southern bypass.
At its eastern end, the B4380 once continued beyond Buildwas through Ironbridge and Madeley (now part of Telford) to a point on the B4379 immediately west of Kemberton. By the 1970s the section east of Coalbrookdale had become part of the A4169. Today's B4373 and the A4169 now cover parts of this former section, although most is unclassified.