Taff Vale Railway Viaduct over Mill Street including masonry weir

A viaduct of coursed rock-faced stone built in 2 phases. The earlier and wider single-track phase is the E side of the bridge. It has a single elliptical skewed arch across the river, and 2 round-headed arches to the S bank, of which the northernmost has an arched watercourse beneath it, while the southernmost is built into the bank. Thick bands are at impost level and beneath the parapet. The parapet is rebuilt. The later phase is also single-track, of 2 segmental arches spanning the river, of which the central pier has rounded cutwaters (the northernmost bay is now occupied by Mill Street, carried over the river on steel piers). A third narrower arch to the S bank is over a bypass channel from a weir beneath the main arches. The parapet is rebuilt and has a projecting band over the R-hand of the main arches only. The abutment to the N side is a later alteration, as it was built to carry a plate girder bridge over Rhondda Road. Built across the later 2 river arches is a weir, comprising a dam of coursed stone approximately 1.2m high, with stone paving to the downstream side. Projecting at the N end is an arched sluice. The main bypass channel is on the S side.