Where larger culverts have a dry weather channel, the wet weather channel can form the mammal run.   Where no dry weather channel is featured, a run should be attached to one or both walls.

The mammal run must extend beyond the culvert and headwall and connect to the bank.  Galvanised mild steel brackets can be fixed to the Wingwall(s) of the headwall to support the mammal run between the culvert and the bank.  The mammal run shelf is normally 500mm wide and situated a minimum of 300mm above the normal water level. 

Where the wildlife tunnel is constructed as a separate structure to the culvert, for instance, where the road severs a Badger run, a headwall can be used with the approaches 'softened' through the use of appropriate planting.  Badger Tunnels are normally 600mm ID Concrete Pipes but if the tunnel is likely to be used by other species it should be increased to 1050mm ID.  The headwall should be set back in the fence line on or very near to the existing mammal run to direct mammals to the crossing.  The fencing should be provided for 500m on both sides of the tunnel entrance, and should be a minimum of 1000mm above ground and 600mm below ground, 300mm down and 300mm towards the direction the mammals approach from.

                                          Wildlife Tunnel Entrance