Anyone with an interest in our signalling heritage simply must pay a visit to Shrewsbury, home to the world’s largest working mechanical signal box, Severn Bridge Junction. This is one of three boxes that can be seen from the station platforms, along with more than two dozen working mechanical signals.
Amongst these, the real gem is SBJ11, a pair of extremely rare lower quadrant centre pivot signals controlling the southern end of platform 7. Severn Bridge Junction is one of two listed boxes at Shrewsbury, the other being the almost equally impressive Crewe Junction box at the north end of the station, where the route to Crewe diverges from the line to Chester.
Signalling at Shrewsbury is an interesting mixture of upper and lower quadrant semaphores, with colour lights controlling exit from the two south facing bay platforms (5 & 6) and the down (northbound) end of platform 4.
As if what can be seen on the station was not enough, a pleasant 15 minute walk through the town and over the River Severn gets you to a fourth box, Sutton Bridge Junction, which controls the Junction from the Marches Line to the Aberystwyth route.
Sutton Bridge was once also the point where the Severn Valley line began and a red brick bridge behind the signal box is a remainder of the lost route to Bridgnorth.
Here again there is a curious mix of upper and lower quadrant, with the most notable signal being a lower quadrant down distant, which stands beneath Severn Bridge Junction’s advanced starter and can be seen – though not easily photographed due to lineside vegetation – from the road leading south outside the Abbey.