Road (congestion) charge zone reminder Vehicles exceeding 14'-6'' in height prohibited Vehicles exceeding height indicated are prohibited. Height is displayed in both metric and imperial units Advance warning of a mandatory height restriction ahead Maximum headroom of 14'-6'' at hazard ahead Maximum headroom of 4.4m at hazard ahead High vehicles to use middle of road at arch bridge ahead Maximum headroom of 12'-6'' at arch bridge ahead Maximum headroom of 3.8m at arch bridge ahead Reduced headroom over part of road due to overhanging building ahead Location of railway or tramway level crossing without a gate or barrier Vehicular traffic must not stop within the area of a railway or tramway level crossing Drivers of large or slow vehicles must stop and telephone before using an automatic railway or tramway crossing Drivers of long low vehicles must telephone to obtain permission before using a railway or tramway level crossing Electrified overhead cable ahead Risk of grounding at a railway or tramway level crossing or hump backed bridge Level crossing with gate or barrier ahead Railway level crossing without gate or barrier ahead Safe height beneath electrified overhead cable ahead Warning of light signals at a level crossing without a gate or barrier ahead Load gauge giving audible warning to drivers where vehicle exceeds safe height under electrified overhead cables Level crossing ahead is crossed by more than one railway or tramway track, and more than one train or tramcar may pass over it in quick succession Direction to emergency telephone or telephone at or near a railway or tramway level crossing Light signal at level crossing for pedestrians Site of emergency telephone or telephone at or near a railway or tramway level crossing New method of controlling traffic at a railway or tramway level crossing ahead Countdown marker to railway or tramway level crossing Countdown marker to railway or tramway level crossing Countdown marker to railway or tramway level crossing Place where drivers of large or slow, or long low vehicles should park near a level crossing while contacting the signal operator Another train or tramcar may be about to pass over the level crossing Open railway level crossing without light signals