What is a Contraflow System?
In the UK, a contraflow system is often used on motorways and other public roads to get traffic moving smoothly if there has been an accident or road blockage. Essentially, the contraflow system is traffic moving in the opposite direction to where they would usually go.
An easier way of remembering what the contraflow system does is by thinking of the word "contra" which means the opposite of. For example, if someone said it's a contraflow, just think it's the opposite of what it should be.
What does the Contraflow System road sign mean?
Contraflow is a method of reversing the flow of one-way roads to allow vehicles to travel in the opposite direction. Contraflow is used only for one-way roads, like a motorway.
Contraflow systems can be differentiated into two types:
A controlled contraflow system allows road users to exit from the highway only at pre-designated sites. The Highway Agency will install contraflow signs on both approach routes, a red arrow pointing toward the contra flowing road and the word "EXIT". These signs are designed with white text on a blue background and a red border. Contraflow junctions will also be marked with triangular white signs, displaying black and yellow arrows pointing toward the exit. A free-flow contraflow system allows road users to exit from the highway. The Highway Agency will install contraflow signs on both approach roads (but no EXIT signs) and on the highway, with a red arrow pointing towards the contra flowing road and the word "EXIT". The contraflow system sign is typically orange and red with black around signalling a contra-flow ahead. You may also see words such as "STAY IN LANE" and "Max Speed", both of which are used to reduce risks.
Contraflows are usually used when an obstruction or incident blocks part of a road network, and traffic must be diverted away from it. This could either be temporary or permanent.
Contraflow is used on some one-way systems in the United Kingdom, including various sections of the A501(M) motorway near Milton Keynes and parts of the A413 road and M4 motorway around Reading. Most one-way systems in the UK are not contraflow, as they consist mainly of residential streets unsuitable for high volumes of traffic. Some towns have introduced similar systems to allow traffic to circulate in both directions around the town center (for example, Kirkcaldy becomes two-way for about a mile at peak times).
You may have seen or been in it before but on motorways, sometimes a 3 or 4 lane motorway is divided up to allow vehicles to pass on both sides due to a possible collision or roadworks. This slows traffic down, however it keeps it moving.
How common is this sign?
Contraflow systems are used in various situations, but they have all been engineered to the same design standard to ensure that the method of operation is the same wherever they are used. This can be seen in how standardized the contraflow signage is. The sign most commonly used for Contraflow systems is point 13 in the Traffic Signs Regulations and General Directions 2002 (TSRGD).
Contraflow is not as common as one may think: As few as 16% of one-way streets in England and Wales had been used for contra-flow from 2000-2011, with a further 6% having been long-term two-way streets before their conversion to one-way use.
Where are you likely to see the "contraflow road" sign?
Hundreds of examples of these signs around the United Kingdom are most commonly used on traffic diverted from motorway networks.
The first permanent contraflow system to be built in the United Kingdom was on the M4 between Junctions 10 and 11 west of London in 1993. This was followed by a system at junction 4 of Surrey's A3(M). As a result, the sign can be found in all areas where routine contraflow operation as part of a motorway network. The sign can also be seen on many major trunk roads where councils have introduced them to reduce congestion in residential areas during peak times or allow buses and cycles through without being held up by one-way streets. The sign can also be seen in many areas affected by road traffic accidents, where it has helped to minimize the delays a long road closure may cause. The sign is commonplace on country roads where there has been an accident or incident requiring traffic diversion, and it is common to find several signs at the same location.
To simplify this question, you will see contraflow system more on motorways, than anywhere else. They can still be found elsewhere, however.
When did this sign first come into action?
Contraflow systems are so commonplace that they are probably taken for granted by many people. This is mainly because, when they were first introduced, there was a lot of opposition from residents who considered them to be dangerous or unnecessary.
Contraflow systems were first used in the United Kingdom in response to the 1977 fuel crisis caused by drought and industrial action at most of Britain's coal mines. Diversion schemes were implemented where possible, although this proved to be impractical in most places as planners found it difficult to implement effective one-way systems as traffic levels were falling or remaining static. In the case of large metropolitan areas, there were so few one-way streets that many people considered that any road was acceptable for two-way traffic unless it was explicitly signed as a one-way system. Urban areas were also affected by the fuel shortages caused by the 1979 Iranian Revolution and 1979 energy crisis in Iran. As a result, most one-way systems in urban areas were introduced after oil supplies in the United Kingdom had returned to normal levels.
Summary
Contraflow systems are frequently used in the United Kingdom to divert traffic away from an incident or obstruction on a major highway.
Contraflow systems were first installed in the UK in response to the 1977 fuel crisis, but have since grown tremendously due to road safety legislation and increased congestion.
Under the Traffic Order 2005 there is provision within England and Wales to use contraflow systems on both existent one-way streets and new roads being constructed. Whilst signs are available at the cost of £7.40, they are only provided where there is an immediate need for these signs due to a motorway incident or obstruction. The Highways Agency produces the signs.
One notable example of a contraflow system was implemented on motorway six in Milton Keynes. Most one-way streets (such as Stone Street) have been converted to two-way traffic since 2013 following an accident or incident requiring emergency traffic diversion.