The route was surveyed in 1793 and authorised by an Act of Parliament in 1795. The proprietors appointed Joseph Hill as the surveyor, who estimated that the project would cost around £50,000. Although the canal had initially attracted strong support from merchants in Bristol, who saw it as part of a link between Bristol and Southampton, many of the shareholders did not respond to the calls for money, and so the company was always short of working capital. The job of constructing the tunnel in Southampton was given to Thomas Jenkins, but the work did not go well, and John Rennie was asked to inspect it. His report highlighted serious deficiencies with the work.