Saltersford Tunnel left, is 424 yards long. Due to bends within the tunnel it is impossible to see boats coming in the opposite direction. In order to make passage safe entry into the tunnel is timed. Northbound boats can enter on the hour until 20 min. after; boats southbound can enter on the half hour until 10 min. to the hour. By comparison Barnton Tunnel, above right, has no deep curves to obstruct your view. This means with care boaters can use the tunnel anytime.
The next tunnel before the Trent and Mersey becomes the Bridgewater canal is Preston Brook and again it has timed access.