the road. The specific alignments and levels of the two tunnels meant that water was able to accumulate beneath the level of the new structure and saturate the surrounding gravels and clays. Just prior to the railway tunnel's planning opening date, saturation of the ground around the area of old the canal tunnel was reported to be responsible for a collapse of a recently constructed 100 yard section at London Road on 23 April 1847. The collapse caused two bystanders to fall into the workings, but they were fortunately unhurt and able to walk out of the eastern entrance. Just over two weeks later, on Thursday 20 and Friday 21 May 1847, Captain Coddington, the Government Surveyor of Railway, was able to inspect the line for the Board of Trade. He spent two to three hours in the tunnel and reported that the recent collapse had been repaired and that he considered the tunnel to be "a very well executed work". However, on 30 May, before the route could be formally opened, a bulge in the brickwork of the tunnel revealed a 60-foot section had begun to sink and the tunnel needed further repairs. The Southampton and Dorchester Railway was officially opened in June 1847 but the Southampton Tunnel section was only able to be opened to traffic two months later when repairs had been completed. Whilst the tunnel alone was closed, passengers were conveyed to waiting trains at either side via specially-chartered buses. Following repairs Captain Coddington visited the site again with Moorsom the engineer and Peto the contractor and reported: As constructed, the tunnel was 528 yards (482.8m) long and when inspected after construction had a maximum of of earth above it. Originally brick lined throughout, the line within rose at a gradient of 1:396 from each end to a point inside the tunnel. Two workmen are recorded as having lost their lives during construction. Operating history and services The tunnel remained in use fulfilling its intended purpose until, in the 1960s, the invert (tunnel base) was found to be rising at one point. Following this and concerns over ground movements in the vicinity of the tunnel extensive remedial work was undertaken between November 1964 and March 1965, with single line working through the tunnel allowing traffic to continue. During this work the heading was reopened between the railway tunnel and the canal tunnel in 1965. This revealed