Directions to Asda Dartford is easy when you cross the bridge keep to the left lane on the toll booths and take the exit ahead up to the doughnut and straight across down the hill cross straight over the next doughnut then left at the next doughnut and Asda is straight ahead! The Tunnel is over 16ft if you take the tunnel on the right the left hand tunnel has a 15ft 9in height limit! 