The bridge which carries the A73 over the infant North Calder Water at Chapelhall, south east of Airdrie is, at first glance, of little interest. The road dips sharply to cross the bridge, with tight bends at each side making it a slow point on an otherwise good road, and the low stone parapets seem to only hold back the branches of the mature trees on the river bank.
However, venture down the steep paths to the river itself (sadly watching the path for broken glass and litter) and you will find an impressive high stone arch. This arch was clearly insufficient for the motor age and has been widened with semi-cantilevered concrete sections on both sides. In order to try and alleviate the sharpness of the approach bends the concrete sections are not parallel to the arch, but skewed with the bulk of the new structure on the western side of the old arch. The concrete also extends to new widended abutments, rising the significant height from the riverbank below, and various concrete fins tie the two/three structures together.
