The Bath branch ran from the junction at Mangotsfield south-east through Warmley, swinging south-west to Oldland and then south east again to cross the Rivers Boyd and Avon beyond Bitton at Saltford. Continuing alongside the Avon, past Kelston Park, the line had to cross the river a further four times before terminating in Bath on the north bank.
From Mangotsfield the Bath branch curved sharply southwards and joined the third side of the triangle, which permitted through running from Bath to Gloucester. Between there and Warmley was the site of the Avon Tramway, which opened in 1832, was horse worked and connected Coal Pit Heath with the Avon at Bitton.
Warmley had a short platform and timber buildings and the yard was red from ochre which was mined locally and sent to paint factories. The 1 in 121 descent from Mangotsfield leveled out here, but the line soon fell again, at 1 in 204, south-west to Oldland Common (the site of the current northern terminus of the Avon Valley Railway). This station, opened in 1935, had a timber platform with corrugated iron shelters and no signalbox. The branch descended from Oldland Common at 1 in 706, shortly steepening to 1 in 121.
Just north of Bitton Station the line passed through a deep rock cutting. The pennant rock from this area yielded the fine building stone for most of the bridges. Nearly 250,000 cu yds had to be excavated. Also, in the cutting, the line ran over the former tramway tunnel which when bored was unlined, but was later lined for 90 ft by the Midland to bear the weight of the branch.
Bitton station, (the current headquarters of the Avon Valley Railway) is built out of local stone and is formed of two pavilions, whilst in the recess between these two is a pierced iron canopy support. The building is not symmetrical as it originally had an additional office at the north end. The up platform had a stone built waiting shelter, cruciform in plan.
South of Bitton Station the line is carried on an embankment 1¼ miles long containing nearly 400,000 cu yds of earth. The River Boyd is crossed by a stone bridge of three arches, followed by a longer bridge over the River Avon into Bath & North East Somerset. (At this point the Avon Valley Railway has constructed a new station “Avon Riverside”).
Kelston Station was opened on 1st December 1869, and closed on 1st January 1949. It was nearer to Saltford than to Kelston, which is three-quarters of a mile away and reached by a path, there being no road access. Only its use by anglers kept the station open for this long; as it was, it was latterly only a halt. Its signals, not regularly used, were to stop expresses for the local squire, a condition under which the station was constructed. Until about 1930 race trains from the north used to stop at Kelston and many passengers alighted and walked to Lansdown racecourse instead of continuing to Bath and reaching the course thence by other means of transport.
The Western Region main line can be seen on the other side of the River Avon and both lines run parallel to Bath. Under the Bath replanning scheme a connection was to be made across the meadows at this point and all Bath passenger traffic was to be handled at a new station near Bath West Goods Depot. An earlier proposal envisaged a cut-off from Kelston, going through the hills to the Somerset & Dorset line near Wellow.