A tunnel structure (10) is described comprising a plurality of cover support members (14) and a cover material (16) supported by and extending over the cover support members (14), the cover support members (14) being of generally arcuate profile and including an upwardly projecting hump (14c), the humps (14c) of the cover support members (14) being aligned with one another such that the cover material (16) defines a ridge (16a) having sides that are more steeply sloped, in use, than the parts of the cover material (16) adjacent the ridge (16a).

A tunnel structure (10) is described comprising a plurality of cover support members (14) and a cover material (16) supported by and extending over the cover support members (14), the cover support members (14) being of generally arcuate profile and including an upwardly projecting hump (14c), the humps (14c) of the cover support members (14) being aligned with one another such that the cover material (16) defines a ridge (16a) having sides that are more steeply sloped, in use, than the parts of the cover material (16) adjacent the ridge (16a).