Blisworth Tunnel sections lined with pre-cast concrete rings. It was also used to test out the materials that were later used on the Channel Tunnel. An unused ring is on display near the south portal. Blisworth Tunnel Blisworth Tunnel is a canal tunnel on the Grand Union Canal in Northamptonshire, England, between the villages of Stoke Bruerne at the southern end and Blisworth at the northern end. The northern end is about from the northern end of the Grand Junction Canal at Braunston, Northamptonshire and the southern end about . At 3,076 yards (2,813m) long it is the third-longest navigable canal tunnel
Blisworth opened on 21 May 1991. The by-pass runs to the west of the two villages, now following a newly created route from Tiffield. The road joins the M1 London to Yorkshire motorway at a new junction created at that time, 15A, at West Hunsbury, Northampton. From Northampton to Blisworth the by-pass closely follows the trackbed of the Blisworth to Northampton railway, long since closed. The new road makes a slight detour near the Northampton arm of the canal at the 'staircase' of locks near Rothersthorpe. The road's construction followed many years of long campaigns in the two villages. The London