The Anderson Committee first established motorway signage in 1957. They designed a system of motorway road signs that drivers could read at high speeds.
MOTORWAY ROAD SIGNS: The Highway Code motorway signs display important information for motorists.
As a rule, all motorway road signs have a blue background with white borders and white lettering. Overhead motorway signs inform motorists of the directions for safe travel.
Motorway signage is also used to provide general information for vehicle drivers and motorcyclists using motorways.
This page explains meanings of gantry signs in motorway advisory speed signs. It is part of the motorway driving rules in the Highway Code.
Rule 255: Motorway signals get used to warn moving traffic that there may be an incident or danger ahead. In most cases you will not be able to see the danger from your vehicle position.
Motorway hazards can include fog, a car accident, or road spillage. The hazard could also be road workers who are carrying out repair work on the carriageway.
You can report a road spillage (e.g. dropped cargo, oil, mud, or sand) to the local council authority or Highways England.
Rule 256: Motorway signals positioned above the central reservation apply to all the lanes.
Motorway overhead gantry signs are often situated on a metal bridge-like structure. Gantries display a framework of motorway signage that gives directions and orders to follow.
Overhead gantry signs get used most often to alert all traffic on busy stretches of motorway. As a rule there is a separate signal for each carriageway on multi-lane motorways.
Rule 257: Motorway flashing amber lights get used to warn traffic of a hazard ahead. The flashing amber signal may also show extra important information.
Examples would be for a temporary maximum speed limit or to show which lanes of the motorway got closed. The flashing speed signs on amber motorway road signs may also display a simple message such as 'Fog'.
If you see amber flashing lights on overhead motorway signs you should adjust the speed of your vehicle. Look out for the source of the danger. Once you pass the danger you will see a signal which is not flashing or one that gives the 'All Clear' message.
Note: Ensure it is safe to increase your speed before heading off or make any overtaking maneuvers.
Rule 258: Flashing red lights on motorway overhead signs require extra caution. You MUST NOT drive in the lane shown as closed beyond the signal if red lights flash on a signal and a red 'X' is showing.
This applies until you pass another signal indicating that the lane is no longer closed, either by displaying the word 'End' or a speed limit sign. Even so, you should always make sure it is safe to proceed before doing so.
You MUST NOT go beyond the signal in any lane if red lights flash on a signal in the central reservation or on the side of the road and lane closed sign is showing.
Lane Discipline: Information on motorway lane rules with clarification on those with 3 or more lanes.
Motorway Breakdowns: Check out the additional rules for safe motorway breakdown procedure.
Motorway Rules: Highway Code procedures for driving on multi-lane highways with fast moving traffic.
Parking Regulations: No waiting and restricted parking laws are viciously regulated and strictly enforced.
UK Highway Code Motorway Signs and Meanings