Braunston Tunnel ft (2.13 m) beam boats to pass. There are three air shafts along its length. The tunnel passes underground alongside another Grand Union Canal feature, Drayton Reservoir, from which the feeder enters the canal at the east end of the tunnel. Braunston Tunnel Braunston Tunnel is on the Grand Union Canal about 830 yds (760 m) east of Braunston, Northamptonshire, England top lock. It is in the northern outskirts of Daventry, about 2 km east of the village of Braunston. Braunston Tunnel is 2,042 yards (1,867 m) in length. Built by Jessop and Barnes, the tunnel has no towpath and
Netherton Tunnel Branch Canal was later converted to electricity and it is now unlit. The air vents that run along the line of the tunnel and provide ventilation, and a shaft of light into the canal, are known by the locals as "pepper pots", because of their shape. They are brick-lined and the openings are covered by an iron frame or grill. The wide bore and good ventilation mean that boats using the tunnel today are allowed to use the power of their internal combustion engines, which is prohibited in the narrower Dudley Tunnel. The tunnel cost £302,000 as opposed to the £238,000 estimate