Mertoun Bridge has no piers built into the bedrock and it goes over the River Tweed.
The piers built between 1 and 3 feet (0.30 and 0.91 m) into the bedrock, which was achieved by using cofferdams, and the depth of the bottom of the piers is between 6 feet 3 inches (1.91 m) and 11 feet 7 inches (3.53 m) below the summer level of the river. 
