You are here: Home » Dictionary
For the newcomer to the roads community, or to the visitor with a casual interest, the increasingly complex and detailed terminology can get quite confusing. Isn't a 'multiplex' a big cinema? Surely a 'trumpet' is a musical instrument? And shouldn't you see a doctor if your 'nose' is merging?
CBRD comes to the rescue with the Dictionary — something approaching a comprehensive glossary of the terms currently used by those discussing British roads. Some are engineering terms, some were created by road enthusiasts, some have multiple meanings. All are defined here as clearly as possible.
If there's something you think should be here but isn't, then let me know and I'll add it to the list.
The following list is, allegedly, in alphabetical order. Click a word to jump to its definition.
- Concerning junctions, access refers to whether or not you can reach a certain road or direction from a given approach to the junction. A junction where not all roads are accessible from all others is limited-access. See also movements.
- Road-sign term used to designate restrictions on the use of a road: "No access for buses and coaches" or "No entry except for access". This always suggests the question: access to what? The houses on this street? The street at the other end? Lincolnshire? Legally, it refers to property adjoining the affected road that is not reachable by any other route, but these restrictions are rarely, if ever, enforced.
Closely related to the idea of grade-separation. A road which is access-controlled is one which can only be entered or exited at certain points, to enable traffic on the road to move more smoothly. Usually this means that minor or private access points are closed off.
Active Traffic Management (ATM)
See Smart Motorway.
An acronym for "advance direction sign" — the large billboard-style signposts erected before reaching an important junction.
A proprietary type of safety fence.
Roads whose numbers are prefixed with the letter 'A'. A-Roads are the busiest and most direct main roads, away from motorways. However, their standard can vary widely, and an A-Road can now vary from a single-track mountain road in Wales to an inner city street or a grade-separated motorway-standard road.
A-Road numbers can be one, two, three or four digits in length.
See also B-Roads.
- An informal term referring to any major road that forms a route through or past settlements. The M1, for example, is an arterial road through the East Midlands, serving Leicester, Derby, Nottingham and Loughborough.
- In the 1930s road-building boom, "arterial" was a road used to describe many new roads built to carry traffic in and out of major cities, and these took their name from the Arterial Road Conference in 1913. Some roads of this era use the word in their official name, such as the A127 Southend Arterial Road.
A technique used when widening a road, where the extra width is added to just one side of the existing paved surface.
A term used to refer to the UK's oddest road classification, the "A-Road with Motorway regulations". These roads are usually bypasses to a section of a longer A-Road which is under motorway restrictions. Such roads are given the A-Road's number, with (M) appended, hence the term Ax(M). They are, in every other sense, motorways.
Possibly the most British of all roadside items. Belisha Beacons are the flashing orange globes on black and white poles that mark zebra crossings. Named for Leslie Hore-Belisha, the Minster of Transport 1934-37, who oversaw their introduction.
The point where a flow of traffic splits in two, most commonly where a sliproad exits the mainline of a road. On British roads, the large two-headed arrow painted on the road surface at these points is called the "bifurcating arrow".
See also diverge.
Colloquial term used to describe a particularly dangerous junction or section of road where incidents frequently occur. Often referred to as an "accident black spot".
Box junctions get their name from the distinctive road marking used on them: a yellow box is painted on the road surface, inside which a grid of diagonal yellow lines is painted. Motorists are not permitted to enter the box unless their exit from it is clear. They may enter the box and wait inside it if their exit is clear but oncoming traffic blocks their path.
Second-class roads, whose number is prefixed with the letter 'B', are known as B-Roads. Their standard varies less widely than other classes of road: B-Roads tend to be either minor country roads connecting villages, or town and city streets. B-Road numbers are only ever three or four digits long.
See also A-Roads.
A method of discouraging through traffic in town and city centres. Bus gates are short sections of road which are blocked off to all traffic except buses (and sometimes taxis too).
A lane reserved for the use of buses, and commonly also taxis and bicycles. They are usually found on major roads in and out of cities to allow public transport to avoid traffic jams, and it is illegal for other types of traffic to use them. They typically operate only for certain hours of the day.
See also bus gate.
A diversion of a major road to carry traffic around a built-up area, in order to improve the journey of through traffic and improve the environment along the original route.
The sloped surface of a carriageway. The camber refers to the way the carriageway is sloped towards one or both edges to allow rainwater to run off easily. Usually the peak is at the centre.
Where two roads meet and, instead of crossing each other, bounce off in a similar way to what happens when two billiard balls run into each other. If you're still not sure, imagine a simple four-way crossroads. Road A and road B meet here. If they cannoned, road A might come in from the north and exit to the east, and road B might come in from the west and exit to the south.
An alternative name for a Marker Post. This name is now technically incorrect as marker posts express distances in kilometres, though on British railways distances are still measured in chains.
See also driver location sign.
A term used by road enthusiasts to refer to the motorway symbol used on British road signs. The symbol is supposed to resemble a motorway, with flyover, in perspective view, but has been likened to two chopsticks in a stand. The start-of-restrictions sign at the entrance to a motorway is therefore sometimes referred to as the "chopsticks sign".
The process of assigning numbers to roads is called classification. The term derives from the fact that, in the very early twentieth century, the process that led to road numbering was originally intended to classify roads according to their traffic levels, and the allocation of numbers for navigation purposes came later.
The name given to a road other than a motorway where stopping, except in an emergency or a specified parking place, is completely forbidden. These roads are marked with special 'clearway' signs: a blue circle with a thick red border, crossed with two diagonal red lines.
Usually abbreviated to C/D lanes. The term refers to additional lanes, usually on a separate carriageway, which run alongside the mainline of a road through a large grade-separated junction. Their purpose is to separate the entering and exiting traffic to avoid disruption to through-traffic where there are several junctions in quick succession.
- Another way of referring to the nine numbering zones that are used to allocate route numbers in the mainland UK.
- Red-orange coloured plastic obstacles used to divert traffic in roadworks or at temporary obstructions to a road. But you knew that already.
Used when describing a junction. Conflict refers to a point where flows of traffic going in different directions must compete with each other for road space: for example, the point where a road feeds on to a roundabout is an obvious point of conflict. The less conflicts a junction has, the more smoothly it will flow. Free-flow junctions omit almost all conflicts; grade-separated junctions remove conflicts from the main through route.
A toll or fine which is levied on vehicles entering a particular zone or section of road, put in place to reduce traffic because of large-scale congestion. London operates a large congestion charging scheme where passenger cars wishing to enter the area inside the Inner Ring Road must pay a toll. A similar scheme exists in Durham and on the A282 Dartford Crossing.
- A technique used when carrying out maintenance on a dual carriageway when the work means that several lanes or a full carriageway must be closed. It involves temporarily transferring traffic in both directions onto just one carriageway to allow the other to be partly or fully closed.
- A permanent lane of traffic which flows in the opposite direction on an otherwise one way street: this is almost always a contraflow bus lane or a contraflow cycle lane.
See Smart Motorway.
Where a major road goes steeply uphill, sometimes a crawler lane is installed in addition to any other lanes on the road, for the use of slow vehicles. It leaves the main traffic lanes free for faster traffic.
A road whose number is prefixed with a letter other than A, B or M. C-Roads are not signposted or shown on maps; they are reference numbers used by local government bodies that maintain roads. Prefixes range from the most common 'C' to 'D' and 'U'.
The angle of slope, relative to the horizontal, of a road's surface.
A lane on a carriageway reserved exclusively for the use of bicycles. Some are marked by solid white lines and may not be used by other traffic; others are marked by broken lines and are only advisory. Often it is legal for other vehicles to park in an advisory cycle lane or to travel in it when necessary.
The state of a road number that was once in use, but is now not allocated to a road.
Department for Transport
The national government body responsible for transport in Britain, and therefore in overall control of the road network. It is mainly responsible for policy decisions, and its responsibilities are carried out by a range of agencies and local authorities.
In having responsibility for funding and maintaining the road network, it is the successor to the Road Board, the Ministry of Transport, the Department of the Environment, the Department of Transport, the Department for the Environment, Transport and the Regions, and the Department for Transport, Local Government and the Regions.
Design, Build, Finance, Operate
Often abbreviated to "DBFO", this term refers to a type of contract under which a section of public road is managed by a private company on behalf of the government, typically for a period of 30 years. The agreement usually requires that the company builds or upgrades the road in some way, and then operates it for an extended period afterwards, during which time the government pays them for doing so. The intention is that the government pays slightly increased costs over the operating period, in return for which it does not have to pay the capital cost of the initial road improvement. Often the payment to the DBFO operator is calculated using ghost tolls.
DBFO schemes operate on parts of the A1(M); on the full length of the M40; on the A50 between Derby and Stoke; and on part of the A35, among other places.
The process of removing trunk status from a road, so it becomes the responsibility of local authorities.
See also trunk road.
An acronym for "Defunct In Original Location". Simon Mold came up with this word to give the folk of SABRE a way of describing one of their favourite types of historical roads.
A road which serves to take traffic from the terminus of a major road and carry it to a large number of exit points, preventing all the traffic being unloaded at just one point. It can also mean a road which carries large volumes of traffic and disperses them through a large urban area, again with the aim being to prevent all the traffic entering the urban area at one single point.
One of the M27's many functions is to act as a distributor road for the M3, allowing its traffic load to be spread around northern Southampton rather than have it all unloaded onto the A33.
The point where two streams of traffic split and go in different directions.
- An official temporary detour from the usual line of a road. Diversions are usually set up because of a temporary road closure, often for roadworks.
- In legal orders, "diversion" is used to describe a permanent change in the line of a road, such as for a bypass around a settlement.
Lowering the status of a road — by giving it a different, less important number or by making physical alterations — in order to discourage its use as a through route. Usually this is done when a newer route is built nearby: for example, the M40 was opened in 1991 and as a result A-Roads nearby were downgraded, the A34 to A3400 and A41 to B4100. It is not quite the opposite of an upgrade.
Driver Location Sign
A type of sign, placed at regular intervals at the side of the motorway, designed to provide the same information as marker posts in a more visible form.
Article on Driver Location Signs
See lane drop.
A road with two separate road surfaces side by side, physically divided by a central reservation. In almost all cases the two carriageways are used to separate traffic moving in different directions. Also known, particularly in the US, as a divided highway. Note that the term "dual carriageway" means that the road has two carriageways and does not refer to the number of lanes marked on the carriageway.
The process of turning a road into a dual carriageway.
- One that uses a roundabout at each side of the major road linked by a bridge.
- A similar scenario to the above, but with an elongated roundabout spanning the major road, pinched together in the middle to use a single bridge or underpass.
A situation where a road numbering anomaly or error has resulted in two separate roads holding the same number. The number is said to be duplicated.
E-routes (or E-roads)
A road with a number prefixed with 'E'. E-routes are a pan-European network composed of existing roads, called the TERN (Trans-European Road Network). Most European countries co-sign the E-routes with their existing road numbers, but in Britain E-routes are never signposted, largely because Britain has no land borders and therefore they are somewhat redundant. They do, nevertheless, exist: the E-15, for example, is better known as the A1 and the E-13 the M1. E-routes connect to mainland Europe by vehicle ferries.
In the 1970s the Department of Transport refused to signpost E-routes unless the network was entirely routed onto motorways: impossible since the motorway network, even today, is fragmented! This can probably be interpreted as a long-term delaying tactic. For a time, the design for a sign to display E-routes existed in the TSRGD, but it was never used.
A road supported on pillars to raise it above ground level. This is most commonly found on urban motorways to enable them to cross surface streets more easily, though it is sometimes done in order to traverse an unusual geographical feature: to hold a road above unstable ground, for example, or run it along a steep hillside.
A point at which you can join a road. Usually this applies to access controlled roads.
See also exit.
Escape Road (or Escape Lane)
A short road, usually lined with a deep layer of gravel, found at the bottom of steep hills to catch runaway vehicles that are unable to stop.
A point at which you can leave a road. Usually this applies to access controlled roads.
See also entry.
- A short additional lane on the approach to a junction, used to stack queueing traffic more efficiently. Often a dedicated left- or right-turn flare lane will open up just before a set of traffic lights.
- Where a junction has been laid out with extra space for future grade separation, the point at which the carriageways of a dual carriageway part around an as-yet unbuilt structure is often called a flare. "Flared carriageways" are often the most obvious indication that a junction is laid out for future expansion.
- A type of trouser that was highly fashionable in the 1970s and was, without a doubt, worn by a lot of people who used the roads at that time.
A bridge carrying one road over the top of another.
An interchange where all the roads involved are grade separated and all movements between them are served by sliproads. A junction is only free-flowing if all of the turning movements through the junction are carried on sliproads and different streams of traffic merge rather than come to a stop.
See also grade separated.
See lane gain.
A particular type of speed camera — possibly the most prevalent type in the UK. Gatso is an abbreviated form of "Gatsometer", the name given to the camera by its Dutch manufacturers.
A fee paid by the government (or one of its agencies) to a private company in return for the company maintaining and operating the road.
The fee is calculated as a fixed payment for each vehicle using the road, so that the company is paid per vehicle in the same way as they would if the road were tolled, but instead of charging road users directly, the charges are paid by the government. It is an arrangement common to many Design, Build, Finance, Operate contracts.
A peculiarly British term used on the most popular road sign. "Give Way signs" are found where one road terminates on another, and inform traffic that it must cede priority to other traffic. Give Way is a shortened version of "give right of way". Before the Worboys report, these signs read "Slow — Major Road Ahead", which means that "Give Way" is a marked improvement in clarity.
See also stop.
- A stretch of road that does not meet any other road or obstacle on the level. Other roads, railways, footpaths and so on are carried over or under the road using bridges. Junctions on this type of road must also be grade separated.
- An interchange where the major route or routes through the junction do not stop and do not cross any other road on the level. Movements to other roads are made using sliproads and bridges to avoid conflicts.
See also free-flow.
See safety fence.
Part of a road numbering system specific to the New Town of Milton Keynes, where the roads are laid out in a grid pattern. "H" stands for Horizontal and designates a road that runs east to west. H-roads all have names that end in "Way" and are numbered from H1 in the north to H10 in the south. The H-roads and their "V" counterparts are marked on relevant roadsigns, particularly where they intersect.
See also V-Road.
A descendant of the roundabout, where one road travels across the central island of the junction. All other traffic and turning movements must use the roundabout. From overhead, the junction resembles a hamburger. This type of junction is, almost without exception, signal controlled. A good example is at M602 J3.
An auxiliary lane at the left of the carriageway, set aside for stopped vehicles and emergency services to ensure the main running lanes on the carriageway remain free from obstructions. On motorways it is illegal to stop on a hard shoulder except in an emergency.
Hard shoulder running
A component of some Smart Motorways where the hard shoulder is used as a running lane. Usually this means that it can be opened at certain times by electronic signs, but in some cases the hard shoulder is permanently open to traffic.
A metre-wide extension of the paved road surface beyond the edge of the carriageway on roads that lack a hard shoulder. Hardstrips are sometimes signed as cycle lanes, but they're really too narrow for this and often littered with drainage gullies and other metalwork, not to mention the detritus that collects at the side of any road.
A term for painted road markings that indicate an area of the road surface that is not intended for normal traffic movement. It normally takes the form of either a solid or broken line around the outside of the area, with diagonal striped markings (or "hatchings") filling the space within.
Hatched markings with broken edge lines can be entered if necessary. Hatched markings with solid edge lines should not be entered except in an emergency.
A term used on road signs warning of low overhead clearance. Headroom is the space available above the road surface before hitting a solid object like a bridge. Posting warnings helps to prevent vehicles hitting a solid object like a bridge.
Highways Agency Traffic Officer
Usually abbreviated to HATO. These officials have been recruited to take over some of the Police's former responsibilities in managing the motorway network. They handle non-emergency work, such as aiding broken down traffic and assisting with traffic management when incidents occur. They are often colloquially referred to as "traffic wombles", a reference to the furry children's TV characters who cleared up rubbish.
- The central point at which radials start.
- The basic central point of the road numbering network. London and Edinburgh are Britain's hubs. The various zones radiate from these two cities.
The term used on road signs to refer to speed bumps.
A road number that, instead of being created as part of a sequence, has been allocated because it sounds memorable. Examples include the A5300, which is part of the Liverpool ring road. There is no A5301 or A5299, at least not nearby.
- A raised area designed to deflect or divide traffic, or to make it easier for pedestrians to cross the road, found in the centre of an area of carriageway. The central part of a roundabout is an excellent example of an island. They are often also referred to as traffic islands.
- In non-technical use in parts of the West Midlands and North West England, a roundabout.
See also ghost island.
A place where two or more roads meet, regardless of how it is laid out or designed.
See also interchange.
The raised section at the edge of the carriageway, used to channel rainwater and perhaps stop stray vehicles. Americans spell it "curb", but in British use that spelling only applies to the verb.
See also running lane.
See also lane gain.
See also lane drop.
Lay-by (or Lay-bye)
A small paved area at the side of the road, intended to allow vehicles to pull off the running lanes and park. Some are simply a wider area of carriageway at the side of the road; others may be larger and partly separated from the road by physical barriers or vegetation.
A place where a road crosses a railway at the same level, requiring road traffic to stop when a train approaches. These come in a variety of flavours: some have automatic barriers, others have manually operated gates and a few have only a set of flashing lights.
A term used on road signs to indicate the act of stopping a vehicle on the road for the purpose of loading or unloading items. It typically refers to restrictions on stopping, that may prevent loading, or which may prevent parking but permit loading. The use of the phrase "loading" usually means "loading or unloading" and no distinction is made between putting items on to a vehicle or taking them off. In simple terms, a vehicle is loading if it is stopped only for as long as necessary to put items on or take items off, and is not left unattended.
For practical purposes this is a type of junction that operates like a stretched-out roundabout. In actual fact it is usually a section of dual carriageway with two one-way gaps in the central reservation that has been appropriated to form one large junction by giving it the priority rules of a roundabout. There is a good example on the A414 in Hertfordshire.
Aside from its obvious meaning, in road numbering terms this refers to a numbered route which does not provide the most direct way between its start and end points. A good example is the A404, which starts in central London and ends west of Maidenhead, but on the way goes almost as far north as Watford.
- A type of sliproad that curves round a very long way. Often used to turn right by turning a very long way left. Think about it.
- Electronic sensor equipment that is buried in the road surface, used either to count vehicles passing over it or to adjust traffic light timings at a nearby junction. Its full name is an inductive loop. Red-light cameras are triggered by loops placed just beyond the stop line. They are also vital to the operation of Smart Motorways.
Low Emission Zone (LEZ)
A scheme introduced across Greater London in 2008 that imposes fines on the most polluting large vehicles. It is part of an experimental scheme that includes similar zones across Europe.
A junction that is functionally the same as a magic roundabout, but has a fundamental difference in that it is much larger. Usually a magic gyratory is comprised of several normal roundabouts connected with short lengths of road. A typical magic roundabout exists on one single junction whereas a magic gyratory is more like a number of nearby junctions working together.
Technically known as a Ring Junction, but that's no fun, is it? A magic roundabout is a two-way roundabout — traffic flows in both directions around the central island, and roads joining the roundabout meet it at a mini-roundabout. It sounds crazy, but these really exist.
See also magic gyratory.
The main part of a road, including lanes and carriageways in both directions, and excluding any other distractions like parallel roadways, side turnings, sliproads, Collector/Distributor lanes and so on. In short, whatever counts as "straight on".
A technique used to control the volume of traffic along a route to maximise capacity downstream. Traditionally it is done with toll gates for bridges and tunnels, but it may see application elsewhere.
See also Ramp Metering.
See Smart Motorway.
Small posts by the side of most motorways and trunk routes giving the distance from the notional start point of that road, placed at 100-metre (0.1km) intervals. They provide a reference point for highway authorities, emergency services and stranded motorists. The Highways Agency has installed larger Driver Location Signs giving this information at 500 metre intervals on some motorways. They are sometimes known as a Chainage Marker.
A generic term for anything painted on the road surface. In the UK, painted road markings are used extensively, not just to demarcate lanes of traffic, but also to convey information about waiting and loading restrictions and sometimes directional information at junctions.
Sometimes referred to as "changeable signs" — electronic displays by the roadside that use LEDs to display a variety of messages. Small matrix signs are installed in the central reservation of motorways at one mile intervals, and larger ones are often used at big junctions or on busy sections of road.
See also variable message sign.
Where two different traffic flows come together and continue as one, designed in such a way that neither should ordinarily have to stop, though one flow usually takes priority over the other. The opposite of a diverge.
A junction with most of the benefits of a normal roundabout, but used in places where space is limited. They are theoretically little different to the American "four-way stop" concept. The central island is painted onto a raised area of the road surface and is usually no more than a few metres across, to allow long vehicles to pass over the top. They are much derided as a means of traffic control as most people simply drive straight over instead of going round, but they offer significant benefits in terms of priority rules and giving equal priority to several roads.
As opposed to a sign that is simply wrong, this concerns direction signs that intentionally omit information for one reason or another. Frequently in practice this means a road number not being displayed on a sign to discourage the use of that road.
A road number which, through normal renumbering or error, is not in the area it should be according to the road numbering pattern. This can range from roads simply out of place within their own zone (like the A403 being near Bristol) to roads numbered completely in violation of numbering rules (like the A42).
A special type of road reserved for motorised traffic only. The UK's motorway network is comparable to Germany's Autobahns, Italy's Autostrade or America's Interstates. Motorways form a network of long-distance dual carriageways, all grade-separated and free of slow-moving or pedestrian traffic. Motorways have numbers prefixed with M or suffixed with (M).
"Motorway Permanent" lettering
Used in the context of describing an interchange, a 'movement' is one of the turns or changes in direction that the interchange allows. A simple crossroads would allow all movements, but more complex motorway junctions might omit some movements that are served by other junctions or roads.
See also limited access.
A SABRE term describing the situation where two road numbers share the same road. In Britain, only one road number may be shown on signs at once so one road must be 'dominant' over the other in a multiplex — or rather, one must be signed and the other invisible. A good example is the M60 Manchester Ring Road, which multiplexes with the M62 in the north-west. Road signs indicate that the road is the M60 leading to the M62.
National Speed Limit
The default speed limit which applies to rural roads without any other posted limit. It is 60mph on single carriageway roads and 70mph on dual carriageways and motorways. The National Speed Limit is not a signal that a road is of a standard suitable for 60 or 70mph; instead it requires drivers' own judgement as to a safe speed. It was introduced temporarily in December 1965, prior to which time 'derestricted' roads had no speed limit. The limit of 70mph was made permanent in 1967, and during the 1970s oil crisis it was lowered to 50mph. Afterwards dual carriageways were restored to 70mph, and single carriageway roads were only lifted to 60mph. Frequently abbreviated to NSL.
A road which provides a bypass for a settlement without being built as one — it simply happens to be in the right place.
See National Speed Limit.
The alphanumeric tag given to a road, such as A642 or M5. Numbered roads are referred to as classified.
Road numbers provide a simple way to refer to a road and to describe a journey through the network. Each road number is unique within the network — though a different letter prefix means a different road. For example, the A621, B621 and M621 are all different roads in different parts of the country.
Someone with an interest in roads. See Odology.
Another way of saying 'the study of roads', derived from the classical Greek hodós (path or way) + logy (theory or study).
A term that describes an improvement to a road that takes place away from its current course. Building a new straighter section of road alongside an existing one, with the intention of replacing it, would be an example of an off-line improvement.
See also on-line improvement.
See also on-slip.
A road that may only be used by traffic going in one direction.
See also contraflow.
An upgrade or other improvement to a road carried out on the line of the existing road. Hence on-line dualling would involve turning the existing road into a dual carriageway, rather than building a new dual carriageway alongside.
See also off-line improvement.
A sliproad used to get on to a road.
See also off-slip.
Another word for a ring road. 'Orbital' tends only to be used for very large or important ring roads — London's industrial-strength ring road, the M25, is the original one. The term is often applied to the M60, and recently Blackburn has started signposting its own slightly less impressive ring road as an orbital too.
A method of widening a road which involves building an entirely new road to one side of the existing one, and then removing the old road. Sounds radical, but it has been done before, most notably on parts of the M5 in Worcestershire which was widened from two lanes to three, requiring the removal of many bridges.
Someone who uses a road by walking along it (or otherwise uses their feet, so joggers and runners and perhaps even people hopping on one foot also count).
See also pedestrianise.
A type of pedestrian crossing that provides parallel walkways across the road for pedestrians and horse riders. The crossing includes push-buttons at a high level for use of those on horseback to avoid them having to dismount.
The name given to pedestrian crossings which use traffic lights to control motorised traffic. "Pelican" is derived from the acronym given to the crossings when they were first introduced in the 1960s — a 'PeLiCon' crossing, or Pedestrian Light Controlled crossing.
- A place where a road is naturally constricted and has lower capacity; a bottleneck.
- A deliberate narrowing of the road or lane to reduce vehicle speeds.
Pollution Control Drain
A term, often abbreviated to PCD, seen occasionally on signs by the side of the motorway. It refers to special drainage systems that are used when oil, fuel or other hazardous substances are spilled on the road to prevent them draining into nearby watercourses or the local environment, and can be used instead to contain the spillage safely.
Some A-Roads are designated as primary routes, indicating that they are more suitable for long-distance traffic. Large towns, cities and places of "traffic importance" across the country (including important bridges or tunnels) are designated "primary destinations". The best routes between these places, wherever they use A-Roads, are designated primary routes.
An A-Road will rarely have primary status over its entire length; most either never have primary status or gain and lose it at some point along the complete route. The upside of this is that navigating is simple if you follow the green signs; the downside is that following a primary route often involves changing route number from time to time.
Primary routes are often confused with trunk roads, but are not the same.
- In everyday conversation, a loose description of a major road.
- A non-trunk A-Road, or in other words, any A-Road maintained by a local authority.
Whichever road, lane or traffic flow is more important and recieves preferential treatment at a junction or junctions is said to have priority. Usually this means it does not have to stop and that other roads or lanes — those without priority — have to stop or give way to it. The general exception is at traffic lights, where everything stops at one time or another: here priority means getting a longer green phase than other roads.
A signal controlled pedestrian crossing, where the lights controlling pedestrians are located at the same side of the road instead of the opposite side. It also includes pedestrian detectors so that the system can customise the crossing time and even cancel the request to cross if the pedestrian presses the button and then walks away.
A British standard practice, both in a wider cultural sense and in a more specific roads sense. On the British road network, a queue is what you encounter when you want to go somewhere.
A road which carries traffic specifically to and from a large settlement. Usually a radial is defined by being one of a number of such roads which all strike out in different directions from their hub.
Ramp Metering involves placing a set of traffic lights near the point where a motorway on-slip joins the mainline. The lights switch quickly from green to red and back, causing small amounts of traffic to enter the motorway in a steady flow. This prevents congestion on the major route by not allowing large volumes of traffic to join the motorway at once.
See also Mainline Metering.
Red Light Camera
A device that is designed to automatically photograph vehicles who pass red traffic lights so that they can be prosecuted. It is triggered with the use of loops in the road surface that detect vehicles crossing the stop line.
See also speed camera.
This term seems to have an unusually large number of official and documented meanings.
- A type of road found in some large urban areas, marked by special "Red Route" signs on entering and easily identified by the existence of red markings painted along the edges of the carriageway. No stopping is permitted on Red Routes for any reason, with limited space made available for short-term parking and loading, and extremely heavy penalties for failure to observe the restrictions. They are designed to keep traffic (and especially buses) flowing on major roads. Red Routes were developed in the early 1990s for use on main roads in London, where they are now well established; they have more recently been created in smaller numbers in Edinburgh, Glasgow and Birmingham.
- Roads managed by Transport for London (TfL). TfL's route network comprises all the capital's Red Routes, as defined above; for this reason they often refer to their network of roads in this way.
- A rural road with a high accident rate in Lincolnshire. Signs erected by Lincolnshire County Council on roads like the A15 north of Lincoln use the term Red Route to raise awareness of the likelihood of accidents.
- A cycle path, segregated from the road network, found in Milton Keynes.
- A traffic island in the centre of a road or dual carriageway, installed so that pedestrians can cross the road in two stages rather than in one for safety reasons.
- A gap in a central reservation where vehicles can wait to turn right.
- An emergency lay-by installed along the side of a Smart Motorway. These are often referred to as Emergency Refuges.
Any set of laws, bye-laws or other legal paraphernalia governing the use of a road.
The term may also refer to motorway regulations, a specific set of rules that govern the use of motorways. In legal terms, a motorway is not a public right of way or a public road, but actually a Special Road. That means that legally it can only be used by motorised traffic: no pedestrians, no bicycles, no animals, no "invalid carriages", no motorbikes under 50cc.
Often more a political word than an engineering one. A relief road is a vague concept, usually referring to a road built to take away most of the traffic on an existing route. The concept is very similar — often indistinguishable from — a bypass.
The term "relief road" is often employed to dress up a big ugly road built through or close to an urban area (since it promises an improvement), such as the A650 Bingley Relief Road, which would have been a bypass if it didn't run right through the middle of the town.
Repeaters are miniature speed limit signs placed at frequent intervals by the side of roads to remind motorists of the speed limit. They are required (in some cases legally) where the default speed limit does not apply — anywhere, in fact, that the limit is not the National Speed Limit in a rural area, 30mph in a built-up area or 20mph in a 20 zone.
The technical name for what is normally known as a Magic Roundabout.
Theoretically, a circular road built around the perimiter of a built-up area as a bypass for traffic from all directions, the idea being to distribute traffic around the edge rather than squeeze it through the centre. In practice, many ring roads in Britain are incomplete — often planned that way — not just with coastal towns but in some cases because traffic volumes on the 'gap' side are not high enough, or for more complex political reasons. The name 'ring road' still applies. London's middle ring roads are called the North and South Circular Roads.
See also orbital.
A type of junction common in Britain, and which is often considered one of the defining features of the UK road network. Its main feature is a circular, one way roadway onto which all the roads meeting at the junction terminate. Traffic approaching the roundabout gives priority to traffic already on it. It then circulates the roundabout until the road it wishes to take. In Britain roundabouts are always clockwise, but for right-hand driving the direction must be reversed.
Contrary to popular belief, roundabouts often have higher capacity and better safety records than traffic-light coordinated junctions, because of their self-regulating nature and the impossibility to 'run' one. The best junction type depends on the exact location, of course.
The Society for All British Road Enthusiasts: an organisation founded in 2001 that is the focus of discussion and learning on all aspects of the British and Irish road networks. The Society operates principally online through its website, www.sabre-roads.org.uk. Its members are Sabristi.
The members of the SABRE community. A term credited to the member Viator. The singular forms are Sabristo (male) and Sabrista (female).
- A dual two-lane motorway in Scotland built prior to 1973 without hard shoulders (in this period, hard shoulders were effectively optional in Scottish design standards).
- "Near-motorway standard" dual-carriageway in Scotland which would have been motorway if built or opened before 1973. Such roads are still built but can no longer be a motorway. Some have motorway-like regulations (and may be secret motorways), others are open to all traffic but operate like a motorway.
Not to be confused with A-Roads that simply have motorway characteristics, such as having grade-separated junctions. A Secret Motorway is an A-Road that not only prohibits certain classes of road user, but which does so by being legally designated a Special Road — the legal term also used for motorways. Despite being created using the legal machinery used to create a motorway, this type of road still appears to be a normal road. Examples include the A1 east of Edinburgh and A55 around Llandudno, but in the latter example, Class IV vehicles are permitted while motorways ban them.
The whole thing is something of a minefield and is, bluntly, a term created by members of SABRE before Special Road legislation was fully understood!
A road which is built to the standard (or very close to the standard) of a motorway, but isn't one.
Sometimes called a service station. Places found on long-distance motorways at frequent intervals providing a place for drivers to stop off the road (since stopping on a motorway is illegal). All must provide free car parking, free toilet facilities, fuel and hot food. Most are now pretty sophisticated affairs, with shops, restaurants and games arcades.
See service area.
Anything that is controlled using traffic lights.
A type of road only wide enough for one traffic lane, but which is still used for two-way traffic. Such roads are prevalent in remote countryside, and into the 21st century some primary and trunk A-Roads were still to this standard.
See also single-carriageway.
A colloquial name for a speed bump — so called because it can make you check your speed while it's lying down.
See also traffic calming.
Sliproad (or slip road)
A system used on certain motorways where electronic signals are computer-controlled to regulate traffic and attempt to reduce congestion. Typically these feature variable speed limits, hard shoulder running and blanket CCTV coverage.
The legal term for roads that are restricted (under section 19 of the Road Traffic Act 1984) to certain classes of vehicle. Motorways are a type of Special Road. They are distinct from a public right of way, because while a normal right of way is open to all traffic except those specifically prohibited by order, a Special Road is open to no traffic except certain classes specifically allowed by order. Non-motorway roads, with motorway characteristics and subject to Special Road legislation, are often referred to as secret motorways.
See also regulations.
A type of speed camera that operates by reading vehicles' registration plates at several points along a length of road and calculating speeds by recording the time each vehicle takes to travel between those points. Their name derives from the name of the company that manufactured them originally, SPEed Check Services. The camera equipment is often yellow in colour, earning SPECS cameras the nickname "yellow vultures".
Raised patches of road surface designed to slow traffic down. This term is abbreviated to "humps" on road signs. They come in several varieties, including speed tables (large humps that extend over a length of road) and speed cushions (small humps confined to one lane only, narrow enough that buses and emergency vehicles pass over unaffected).
See also traffic calming.
See also red light camera.
Every inch of public road in Britain has a speed limit — a maximum permitted legal speed for that section of road. It must be posted on signs when the limit changes. Most roads — especially those not surveyed to find a safe limit or those outside built-up areas — are subject to the National Speed Limit.
See also repeater.
All spurs must have a 'parent' road which they exist to serve and which they connect to another road or place. Frequently a spur will be of a similar standard to its parent and will often assume its number, and will in almost all cases terminate on its parent rather than go across it. The M23 motorway, for example, has a spur to Gatwick Airport, which is also numbered M23. This duplication of numbers is safe since any traffic on the M23 spur will be going to or from the M23 proper.
See also number.
- A red octagonal road sign that indicates a particularly dangerous junction, usually because of restricted visibility for traffic emerging from a side road onto a major road. Drivers are expected to come to a full stop when they encounter one. It is used very sparingly in the UK and it is much more common to find Give Way signs.
- Something you should do when you encounter a red traffic light.
A single-carriageway road with three lanes. The central lane is for use by vehicles overtaking in either direction, and is used by fast moving vehicles in opposite directions, neither of which has priority over the other. The name derives from the observation that the three lanes are "left side, right side and suicide". This term overplays the risks involved in using them, but it's certainly true that a road with a shared bi-directional overtaking lane is less safe than one where each lane is reserved solely for traffic travelling in one direction.
Suicide lanes were once very common in Britain, particularly before motorways existed when they could be found on many long-distance rural roads. Many former trunk roads have two very wide lanes, where the road has simply been repainted from the original three.
The angle of a road's surface as it turns, with the carriageway banked to slope downwards to the inside of the corner. This assists vehicles in cornering.
A technique used to widen a road which involves adding an equal amount onto each side of the existing road surface.
The place where a diverging or merging lane appears or disappears gradually. For a standard merge, for example, the taper is the length of road between the tip of the merge nose and where the merging lanes disappear completely.
A type of traffic island painted onto the road surface to divide the lanes of a two-lane sliproad where it joins the main carriageway. It is used on sliproads carrying large volumes of traffic to space out the points where traffic merges. It is also used less regularly at busy diverges.
A fee charged to motorists for using a road or section of road. Traditionally in Britain these only apply to privately run toll roads, or tunnels and bridges where the excessive construction costs are repaid by the tolls.
See also ghost toll.
A situation where a continuous route number departs from the mainline of the road ahead. Totso is an acronym for 'Turn Off To Stay On', since this is what you have to do at one. For example, if you head up the A30 from Exeter, you have to turn right at a totso to remain on the A30, since the road ahead is the A303. The through road at the junction does not retain one number.
Very similar to a pelican crossing, with one red pedestrian light and two green, one showing a green man and one a bicycle. Some early examples segregated pedestrians from horses and cyclists, with each having separate lights. The name Toucan is derived from the idea that 'toucan' cross at once. It's not a very good joke.
Technically this term applies to anything that uses a road to move around, though usually it refers to motorised vehicles like cars, buses and lorries.
Where obstacles such as speed bumps, chicanes, traffic islands and mini-roundabouts are placed on roads with the intention to slow down traffic, the practice is referred to as traffic calming. Frequently these measures are applied on roads used as shortcuts or as racetracks by less responsible motorists. In some places they are criticised, with claims that they may simply provide a more exciting obstacle course for irresponsible drivers, or that they increase congestion on surrounding roads.
Any build-up of traffic. Despite the frequency with which traffic jams can be found on the roads, nobody has ever successfully tasted one to see what flavour it is.
Sets of red, amber and green lights by the side of the road used to control traffic. (I hope you knew that already.) Used in a variety of situations, from junctions to roadworks and fire stations. Sometimes called traffic signals.
See traffic lights.
The correct name for the lettering used on UK road signs. There are two "Transport" alphabets: Transport Heavy and Transport Medium, both designed by Jock Kinneir and Margaret Calvert. They are modified versions of "Aksidenz Grotesk", adjusted to improve clarity and readability.
See also "Motorway" lettering.
The branch of the Scottish Government with responsibility for roads, railways and other modes of transport in Scotland. It is directly responsible for trunk roads in Scotland.
A road operated and maintained by national government. In England these roads are managed by the Highways Agency; in Wales by Transport Wales; and in Scotland by Transport Scotland. All other roads are the responsibility of local authorities. In Northern Ireland the situation is slightly different, as all roads are maintained by the Northern Ireland Roads Service, and there is no distinction between trunk and non-trunk roads.
Trunk road status is never visible to road users — road numbers, signage, classification and primary status are all completely disconnected from trunk status. An attempt was made in Scotland to remove all non-trunk primary routes, thus making trunk routes and primary routes the same, but it failed and the two remain unrelated.
See also detrunk.
A type of speed camera that is often mounted in such a way that it faces towards oncoming traffic to photograph the front number plate. "Truvelo" is actually the name of the company that manufactures the cameras. Their products are typically painted blue and yellow.
The Traffic Signs Regulations and General Directions, a document published by the Department for Transport which sets out the correct standards for traffic signs in the UK. It is periodically updated with new designs. Signs that do not conform to TSRGD are an unlawful obstruction to the highway. It is one of the few acronyms on this page that is only rarely written or spoken in full, which is why it appears here in its abbreviated form.
A road which has no number. Numbered roads are referred to as classified, therefore a road with no number is unclassified. Most unclassified roads are actually given numbers by the highway authorities responsible for maintaining them, but these numbers are only for internal use and should not appear on road signs.
See also C-Road.
The opposite of a flyover — a bridge carrying a road under another road. In many ways it's a flyover seen from the other point of view.
An improvement to a road, almost always referring to a physical improvement such as widening the carriageway or rebuilding a junction. It might also refer to promoting the road to a more important number.
See also downgrade.
Just like a regular motorway, except it's built in an urban environment which means it is subject to lower design standards, often with closely spaced exits and entries, narrow lanes, tight corners and, frequently, no hard shoulder.
A slightly misleading term coined by road enthusiasts. It refers to a specific type of multiplex where the signposted (dominant) numbered route terminates at the end of the multiplex instead of splitting off again and going its own way. They are termed "useless" because there's no need for the two routes to run concurrently if one is going to end, but actually they only ever exist to make navigation simpler, in locations where motorists are more familiar with one number than another and it is helpful to continue the better-known number instead of switching to a different one.
Part of a road numbering system specific to the new town of Milton Keynes. The "V" stands for Vertical and designates a road that runs north to south. V-roads all have names that end in "Street" and are numbered from V1 in the west to V11 in the east. The V-roads and their "H" counterparts are marked on relevant roadsigns, particularly where they intersect.
See also H-Road.
Variable Message Sign (VMS)
A sign which is capable of changing to display a number of messages. These can be in the form of a matrix sign or a panel which can rotate to expose several different sides displaying different messages. The latter type is common on car park direction signs in city centres, with panels which are remote-controlled to rotate, displaying "Space", "Nearly Full" or "Full".
Variable Speed Limit (VSL)
A motorway speed limit that can be changed to suit traffic conditions, controlled by electronic matrix signs and legally enforceable. It is successfully used to reduce congestion by reducing the gaps between vehicles and thus increasing throughput.
See also Smart Motorway.
The space along the side of the carriageway, when no footpath is present — usually grass but sometimes paved.
See Variable Speed Limit.
A term used on road signs to refer to restrictions on vehicles stopping on a road. While "parking" refers to stopping a car and leaving it unattended, "waiting" refers to stopping a car at the roadside so that passengers can get in or out.
Found on the main carriageway of a road between points where a new lane joins from a sliproad and exits again at another sliproad shortly after. The weaving section is the space between the entry and exit where traffic quickly weaves between lanes.
In the early 1960s a government committee produced a document known as the Worboys Report (after the head of the committee) which made recommendations for a new scheme of road signage. The scheme, which is still in use today, has become known as Worboys signage.
A yellow line is a painted marking at the edge of the carriageway that is used to show that parking restrictions apply. Lines painted along the edge of the road indicate parking or waiting restrictions, while lines painted on the edge of the pavement at right angles to the road indicate loading restrictions.
Single yellow lines or marks indicate a part-time restriction that will be fully explained on nearby road signs. Double yellow lines or marks indicate a full-time restriction.
The American equivalent to Give Way. This term also seems to have appeared on a handful of very early Give Way signs.
A pedestrian crossing which relies on road traffic giving priority to pedestrians when one is waiting to cross. They are named for the zebra-like black and white stripes painted across the carriageway. An integral feature of British zebra crossings are Belisha Beacons.
The name usually used to refer to the nine areas of mainland Britain that are used to allocate road numbers. The zones are divided by A-Roads with single digit numbers. Sometimes also called cones because most are triangular (sort of, if you use your imagination).
With thanks to...
In no particular order — Chris Long, Chris Williams, Kevin, Jeff Wagstaff, Mike Wilkinson, Paul Evans, Clive Harmson, Ted Pottage, Kevan Fleckney, Michael Elliott, John Rowland, Doug Farnan, Keith Jones, Peter Hadrys, Mark Ellerington, Paul Everitt, Brian Davies, James, Robert, Toby Speight, Dave, David Summers, Pete Harman, Ash, Paul Gowen, Martin Vlietstra, Alan Whittingham, Steven Jukes, Jack Robinson, Andy Emmerson, Guy Barry, Simon M4Man, Chris 'Awkward' McKenna, David D Miller, Peter Edwardson, and Simon Mold, all of whom have stopped this page being as inaccurate as it used to be.