From Warminster And District Archive magazine, No.4, May 1990:
Cannimore Underpass
This structure provides a bridleway and a private road [Cannimore Lane] crossing under the Bypass at a skew of 23 degrees. The width of the private road is 3.5 metres with half metre verges on either side. The clearance provided is 4.8 metres. The structure consists of a reinforced concrete box having equal floor, wall and roof thicknesses of 500mm. At the ends, integral reinforced concrete splayed wing walls are provided.
Here the Bypass is on an embankment and runs 2 metres above the roof of the underpass. The structure has 2 partial contraction joints at third points along its length and at each wing wall extension. The steel reinforcement is continuous through each joint, the concrete is keyed and the joints sealed against water ingress by an external plastic waterstop and a sealant on the inside faces.