Blisworth Tunnel was the only section unfinished. This was despite the tunnel having been under construction for seven years: the gap was filled by a temporary horse-drawn tramway over the top of the hill, with goods being transported from boat to wagon and back again. The tramway, built in 1801, was Northamptonshire's first railway. In March 1805, the tunnel was finally opened and the rails were used to connect the main line of the canal to the River Nene until the branch canal to Northampton was constructed. Until the 1870s travel through the tunnel was only achieved by men lying on their
William Jessop and the Pontcysyllte Aqueduct built by Thomas Telford. It is known as the Cosgrove aqueduct and was designed and built by Bevan. Two tunnels also had to be built, at Braunston and Blisworth. The Blisworth Tunnel caused great problems, and was unfinished when the rest of the canal was ready. In fact Jessop considered abandoning it and using locks to carry the canal over the ridge. Jessop's temporary solution was a railway line laid over the ridge to carry traffic until the tunnel was completed. The Grand Junction Canal was enormously important in encouraging trade between London and the Midlands.