The eastern end of the tunnel was about 40 yards due west of the junction with the Northam Branch. Originally the tunnel was intended to be 880 yards (805m) long but in March 1797 this length was reduced to about 580 yards (530m). It seems that about 50 yards (45m) at the west end was to be constructed as a cutting and the tunnel cut short by some 250 yards (230m) at the east end where the top of the tunnel would have been only a few feet below the surface. It is not known how close construction of the tunnel got to completion, but it is unlikely that it was ever navigated.
It should be remembered that the canal’s water level would have been some 12-15 feet lower than the present road surface. The site of the tunnel entrance is about 30 yards west from the fence between the park and Palmerston Road. Considerable areas of the park were raised in level to dispose of the spoil generated by excavation of the railway tunnel.
The tunnel passes under Above Bar and in front of the present Civic Centre. The railway tunnel crosses over the canal tunnel at a very oblique angle under Civic Centre Road just west of West Marlands Road.
The tunnel emerged at its western end to the north-west of the later railway tunnel portal just north of Kingsbridge Lane in land that is now just outside the rear of the BBC Broadcasting Centre.
Kingsbridge Lane to Central Station Bridge
The canal would have left the tunnel in a cutting some 12-15 feet deep until it was at ground level by the western end of Kingsbridge Lane. When the canal was opened from Redbridge in December 1802, the usable canal would have ended near the bottom of the hill on what is now Blechynden Terrace.
The line of the canal ran just above high water mark. The road called Blechynden Terrace was built on the site of the canal. Before the coming of the railway there were plans to make Blechynden into a pleasant suburb with rows of good houses with ornamental gardens facing the water of the River Test. Blechynden Terrace actually dates from this time but the building of the railway prevented the completion of the project. In the period 1845-7, the railway was constructed on the foreshore around 60 yards south of the road.
Southampton’s railway station has changed since the station originally called Blechynden opened in 1847. This small station was situated just east of the present footbridge over the railway. In 1858, this was renamed Southampton West End. By the late 1880s the station was inadequate for its traffic, so land was bought for a new station nearby and Southampton West station was opened on 1 November 1895, while Southampton West End closed to passengers. Southampton West station was enlarged in 1933-34 when land was being reclaimed for the New Docks and was renamed Southampton Central. In 1967 the station was rebuilt and, following the closure of Southampton Terminus station the year before, was renamed simply Southampton. This reverted to Southampton Central in 1994.
A one arched canal bridge was built (see the pencil sketch below) carrying what was to become Sidford Street over the waterway. This road was effectively an extension of Hill Lane to reach the sea shore. The bridge had disappeared by 1846 and Sidford Street was in turn demolished in 1972 for redevelopment. The site of the bridge is near the western end of Starbucks Coffee in Grenville House. The Central Station Bridge was constructed as part of the building of the vast "New Docks" (now Western Docks) between 1927 and 1934, which led to all of West Bay being reclaimed and the station becoming landlocked.
Central Station Bridge to Millbrook Station
West of Southampton Central station, the canal ran at the foot of a small cliff or steep slope. It was reported in the 1960s that there were traces of the canal within the trees at the bottom of the slope but that it was very overgrown. It is not known whether this stretch remains today.
The canal continued to run along the shore of the tidal River Test for most of the way to Redbridge. When the railway was first built here it joined the line of the derelict canal in the vicinity of the north end of the signal gantry at the eastern end of Saxon Road. The railway as built was two track and also running along the shore. It was widened southwards onto reclaimed land during 1933-5 when the New (Western) Docks were being built. At this time, the original tracks which had followed a slight bend in the line of the canal west of Norman Road were straightened although a siding still occupies the old alignment.
It is possible to walk along the southern side of the present railway between Southampton Central and Millbrook stations.