Tunnels

Special tunnel cantilevers are fitted to the roof of a tunnel. Mk 1 tunnel equipment had additional arms between registration points where only the catenery wire is supported. Note that the stagger is less than on main running lines and for push off arms the stagger is a negative.


Not all tunnels where built to minimum clearance as in the examples above. In some tunnels it was possible to keep the contact wire at normal height.  Other tunnels had to have the floor lowered. Ipswich tunnel has had this done twice, first time for the installment of  overhead wires the second to allow for taller containers.

The mast at the entrance to a tunnel where it is necessary to reduce either or in some cases both the contact wire height and the encumbrance are the same as those found either side of an over bridge. There are a few locations, the bridge at Harlow Town station being one, where tunnel cantilevers are used under bridges.