Dictionary
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For the newcomer to the 'roads community' or to the visitor with a casual interest, the increasingly complex and detailed terminology gets 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' has a merge? CBRD comes to the rescue with the Dictionary - something approaching a comprehensive glossary of the terms currently used by those discussing British roads. The definitions don't go into every detail of the terms, but aim to provide a sound introduction to the word.
If there's something you think should be here but isn't, then let me know and I'll add it to the list. And if you're looking for the meaning of abbreviations like D2 or S2, there's a separate page about abbreviations.
The following list is, allegedly, in alphabetical order. Click a blue word to jump to its definition.
Jump to: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
Access
- 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 types of vehicle that can use a road: "No access for buses and coaches".
Access Controlled
Similar to grade-separated. 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.
Active Traffic Management (ATM)
A system used on certain motorways where gantry signs are computer-controlled to set variable speed limits, open the hard shoulder as a running lane and limit the volume of traffic entering at junctions, with the aim of improving the flow of traffic. CBRD has an In Depth page about ATM.
ADS
An acronym for "advance direction sign" - the large billboard-style signposts erected before reaching an important junction.
All Purpose Road
The opposite of a motorway: a road which can be used by any traffic, not just motorised vehicles, and which is therefore all-purpose.
A-Roads
A road whose number is prefixed with an 'A'. These were originally intended to be the major routes, but because of inconsistent upgrades and policies, an A-road can now vary from a single-track mountain road in Wales to a grade-separated motorway standard eight lane dual carriageway like the A2 in Kent. To help clear up the mess, in the 1960's primary status was introduced. A-road numbers can be one, two, three or four digits. See also B-Roads.
Applied
One of Guy Barry's suggested 'branches' of Odology: 'pure' and 'applied'. 'Applied' road studies are those which concern the practical application of what is being discussed. Therefore Applied Odology might include the redesigning of an interchange to better serve the traffic using it. See also pure.
Arterial
Used to describe a major road which 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. See also bypass; radial.
Asymmetric Widening
A technique used when widening a road, where the extra width is added to just one side of the road. See symmetric widening, parallel widening.
At Grade
An interchange where all the roads concerned meet at one level, requiring traffic from all directions to come to a stop. The opposite of grade-separated.
Ax(M)
A term used to refer to the UK's oddest classification, the "A-Road with Motorway Restrictions". Essentially these roads are a short section or bypass to an A-road which has been built and operates as a motorway. Such roads are given the A-road's number, with (M) appended, hence the term Ax(M).
B
Belisha Beacon
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.
Bifurcation
The point where one 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".
Black Spot
Used to describe a particularly dangerous junction or section of road where accidents frequently occur.
Bottleneck
A junction or section of road that has lower traffic capacity than the road either side, and is therefore a cause of frequent congestion.
B-Roads
A second-class road whose number is prefixed with a 'B'. Less wide-ranging 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.
Bus Gate
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). See also pedestrianise; bus lane.
Bus Lane
A lane preserved for the use only of buses and taxis, usually found on major roads in and out of cities to allow public transport to avoid traffic jams, and forbidden to all other traffic. Frequently bus lanes are also available for use by bicycles and taxis, and operate only certain hours of the day. See also bus gate.
Bypass
A diversion of a major road to carry traffic around a town or city, in order to reduce traffic levels and improve the journey of through traffic. See also arterial; radial.
C
Camber
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. See also crossfall and superelevation.
Cannoning
Where two roads meet and, instead of crossing each other, bounce off in a similar way to what happens when two billiard balls bounce off 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 south and exit to the west, and road B might come in from the east and exit to the north. Clear now? Because it's such a long-winded thing to have to explain, Guy Barry very kindly supplied the word 'cannon'.
Carriageway
The surfaced part of a road intended for wheeled traffic. Distinct from a lane. See also single carriageway; dual carriageway.
Catenary Lighting
A special type of road lighting where the lamps are suspended on a high-tension wire suspended from a row of masts in the central reservation of a dual-carriageway.
Central Reservation
The dividing strip between two carriageways, and therefore a central feature of a dual carriageway. Sometimes called a median.
Chainage Marker
An alternative name for a Marker Post. This name is now technically incorrect as marker posts no longer give distances in chains.
Clearway
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.
Cloverleaf
A type of four-way free flowing interchange. See the interchange dictionary page.
C/D Lanes
Short for Collector/Distributor Lanes. Additional lanes, usually on a separate carriageway, which run alongside the main carriageway of a road through a large grade-separated junction. Their purpose is to pick up all the entering and exiting traffic to prevent disruption of traffic on the main carriageway.
Cones
1. Another way of referring to the nine numbering zones.
2. Metre-high orange plastic obstacles used to divert traffic in roadworks or at temporary obstructions to a road. But you knew that already.
Conflict
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.
Congestion Charge
A toll or fine which is levied on vehicles, put in place to reduce traffic because of large-scale congestion. London now has an experimental congestion charging scheme in the city centre, where passenger cars wishing to enter the area inside the inner ring road must pay a £5 toll. A similar scheme exists in Durham and other cities are looking to introduce them too.
Contraflow
1. A technique used when carrying out maintenance on a dual carriageway which requires several lanes or a full carriageway to be closed. It involves temporarily transferring traffic in both directions onto just one carriageway to allow the other to be partly or fully closed.
2. A permanent lane of traffic which flows in the opposite direction on a one way street: this is almost always a contraflow bus lane or a contraflow cycle lane.
Controlled Motorway
A motorway where a computerised system involving traffic-detection loops embedded in the carriageway and electronic displays above lanes regulates and controls traffic flow. Speed limits are automatically controlled, lowering as traffic increases to increase the capacity of the road and prevent congestion. A trial scheme on the M25's south west quadrant has been running with great success for several years.
Crawler Lane
Where a major or busy road goes uphill, sometimes a crawler lane is installed in addition to any other lanes on the road, for slow vehicles to use. It leaves the main traffic lanes free for faster traffic.
C-Road
A road whose number is prefixed with a C. C-roads are not signposted or shown on maps: they are reference numbers used by the government bodies that maintain roads. Some also use D-roads and U-roads. Lots of information is available in the Great C-Road Hunt page. See A-Road; B-Road; unclassified.
Crossfall
The angle of slope, relative to the horizontal, of a road's camber.
Crossroads
A simple four-way junction where two roads cross roughly at right angles. Twice as good as a T-junction.
Cycle Lane
A lane on a carriageway reserved exclusively for use by bicycles.
D
"David Craig" Number
A SABRE term, referring to David Craig's (incorrect) theory that roads (especially A-roads) with three digit numbers are derived from the roads they connect. Examples include the A404, which links the A40 to the A4, or the M621 linking the M62 to the M1.
Defunct
The state of a road number that was once in use, but is now not used.
Detrunk
The process of removing trunk status from a road, so it becomes the responsibility of local authorities. See trunk road.
Diamond
A very basic type of motorway interchange. See the interchanges page.
Diol
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.
Distributory Road
A road which was built or serves to take traffic from the terminus of a major road and carry it to a large number of exit points to prevent 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. A good example of the former definition is the M27, which distributes the M3's traffic around northern Southampton instead of all the traffic being unloaded onto the A33.
Diverge
The point where two streams of traffic split and go in different directions. See also merge and nose.
Diversion
A detour by any other name. Usually caused by a temporary road closure, diversions are an alternative signposted route around the blockage.
DfT
The Department for Transport. The national government body responsible for transport in Britain, and therefore in overall control of the roads. Until recently was the DTLR.
Downgrade
Lowering the status of a road - by giving it a different, less important number; a lower classification or physical alterations - in order to discourage its use as a mjor road. 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. Not quite the opposite of an upgrade.
Drop
See lane drop.
DTLR
The Department for Transport, Local Government and the Regions. This government department no longer exists, but up until mid 2002 was responsible for Britain's roads. There are still frequent references to it in writing about roads. It is now the DfT.
Dual Carriageway
A road with two separate road surfaces side by side, with a central reservation in the centre to divide them, usually in the form of a grassed strip or crash barrier. In almost all cases the two carriageways are used to separate traffic moving in different directions. Note that the term 'dual carriageway' is not related to the number of lanes a road has. See also single carriageway; carriageway.
Dualling
The process of turning a road into a dual carriageway.
Dumbell
A type of grade-separated interchange. It can take two forms:
1. One that uses a roundabout at each side of the major road to connect sliproads to the minor road.
2. A similar scenario to the above, but with an elongated roundabout with both sides pinched together in the middle to use a single bridge or underpass.
Duplicate
Where some road numbering anomaly or error has resulted in two separate roads holding the same number. This goes deeper the more you look into it: examples are starting to show up of triplicated roads too.
E
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 signed, largely because Britain has no land borders and therefore they are somewhat redundant. They do, nevertheless, exist: the E15, for example, is better known as the A1 and the E13 the M1. E-routes connect to mainland Europe by vehicle ferries. In the 1970's the Department of Transport refused to signpost E-routes unless the network was entirely routed onto motorways: impossible since the motorway network remains fragmented! This can be seen as a long-term delaying tactic. For a time a sign existed to display E-routes but it was never used.
Elevated
A road supported on pillars to raise it above ground level. Usually this is done on urban motorways to enable them to cross surface streets more easily, or to traverse an unusual geographical feature: to hold a road above unstable ground, for example, or run it along a steep hillside.
Entry
A point at which you can join a road. Usually this applies to access controlled roads. See exit.
Escape Road
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.
Exit
A point at which you can leave a road. Usually this applies to access controlled roads. See entry.
F
Filter Arrow
A green arrow on a traffic light used to allow some turning movements at a signalised junction during the red phase.
Filter Lane
A handy little lane used to turn left at a junction, frequently at roundabouts or traffic lights, which avoids using the junction itself.
Flyover
A bridge carrying one road over the top of another. See also overbridge, overpass and underpass.
Free-flow
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 none of the movements through the junction involve coming to a complete stop, with the exception of sliproads merging into each other or the main carriageway. See grade separated.
G
Gain
See lane gain.
Gantry
A platform elevated across all or part of a carriageway to support overhead signs, Variable Message Signs or traffic lights.
Gatso
A speed camera by any other name, designed to photograph vehicles travelling above the speed limit so they can be fined. Gatso is an abbreviated form of "Gatsometer", the name given to the camera by its Dutch manufacturers.
Give Way
A peculiarly British term used on the most popular road sign. "Give Way signs" are found where a road terminates on another, where most other countries would place a "stop" sign. Give Way is a shortened version of "give right of way". Before the Worboys report, these signs actually read "Slow - Major Road Ahead": Give Way is a marked improvement. Stop signs are reserved for more dangerous junctions (once reading 'Halt - Major Road Ahead').
Gore
The American term for the nose of a diverge.
Grade separated
1. A road (or section of one) which 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.
2. 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.
Grade separation
The process of making a road or junction grade separated.
Gyratory
Generally speaking, a very loose term, though it has become known in the roads community as a large traffic-light controlled roundabout.
H
H-Road
Part of a road numbering system specific to the new town of Milton Keynes. Built on the American grid road system, the 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.
Hamburger
Sometimes called a throughabout. A descendant of the roundabout, which allows one road to travel across the central island of the junction. All other traffic and turning movements must use the roundabout. As a consequence the junction must be signal controlled. A good example is M602 J3.
Hard shoulder
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 is is illegal to stop on a hard shoulder except in an emergency.
Hard Strip
A 1 metre wide extension of the paved road surface beyond the edge of the carriageway. 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.
HATO
Acronym for a Highways Agency Traffic Officer. These new officials have been recruited to take some of the work in managing the motorway network from the police. They handle non-emergency work, such as aiding broken down traffic and assisting with traffic management when incidents occur.
Headroom
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).
Highways Agency
Often abbreviated to HA. The Highways Agency is the government agency in direct control of trunk road in England. It is an executive agency of the DfT. See DTLR.
Hub
- The central point which radials start at.
- The basic central point of the road numbering network. London and Edinburgh are Britain's hubs. See number, zone.
Hybrid junction
A junction, or more usually an interchange, with a unique layout which is composed of components that are recognisably part of more common junction types.
I
Interchange
A junction by any other name. The word interchange is usually used to describe a large, complex or grade separated junction.
Invented Number
A road number that, instead of being created as part of a sequence, has been dreamed up to sound memorable. Examples include the A5300, which is part of the Liverpool ring road. There is no A5301 or A5299, at least not nearby.
Island
1. A traffic island by any other name: a raised area not for use of traffic, rather to deflect or divide it, found in the centre of an area of carriageway. The central part of a roundabout is an excellent example of an island.
2. In slang used in parts of the West Midlands and up to Manchester, a roundabout.
J
Junction
A place where two or more roads meet, regardless of how it is laid out or designed.
K
Kerb
The raised section at the edge of the carriageway, used to channel rainwater and perhaps stop stray vehicles. Spelt "curb" by the Americans.
L
Lane
A section of a carriageway marked out for use of traffic, usually only in one direction. Carriageways are frequently described by their width in terms of lanes.
Lane Drop
Where a sliproad leaves the main carriageway, taking one of the lanes with it, causing the main carriageway to 'drop' a lane. See also lane gain.
Lane Gain
The opposite to a lane drop - where a sliproad joins and forms a new lane, causing the main carriageway to gain a lane.
Level Crossing
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, with automatic barriers, manually operated gates or nothing but some flashing lights.
Limited Access
Pretty much the same thing as access-controlled.
Llewellyn-Smith
The name of the typeface used on British road signs prior to the Worboys Report, after the men responsible for its design.
Longabout
Essentially this is an extra-stretched roundabout. In actual fact it is a section of dual carriageway with two one-way gaps in the central reservation, so that the existing road functions as a roundabout. There is a good example on the A414 in Hertfordshire.
Long Way Around Route
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.
Loop
- A 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.
M
Magic Gyratory
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. The key difference is that, while it is effectively a circular roadway that can be used in both directions, a magic gyratory does not have the disorienting effect of a magic roundabout because each connection point is self contained.
Magic Roundabout
Technically known as a Ring Junction. 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 - at Swindon (the original Magic Roundabout, formerly known as County Islands); at M40 J1; in High Wycombe and a number of other locations. See also magic gyratory.
Mainline Metering
A technique used to limit access along a route to maximise free-flowing capacity downstream. Traditionally done with toll gates for bridges and tunnels, but may see application elsewhere, e.g. on the M8 westbound at junction 6. Closely related to Ramp Metering.
Marker Post
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 is currently trialling larger blue-and-yellow signs giving this information at 500 metre intervals on some motorways. Also known as a Chainage Marker.
Matrix Signs
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.
Merge
Where two different traffic flows come together and continue as one. The opposite to a diverge.
Mini-Roundabout
Has all the benefits of a normal roundabout, but used in places where space is limited. These are used where a "four-way stop" would be found in the US. 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. Much derided as a means of traffic control as most people simply drive straight over the top instead of going round. See traffic calming.
"Misleading" Sign
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 use of a road.
Misplaced Number
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 near Bristol) to roads numbered completely in violation of numbering rules (like the A42).
Motorway
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). See also regulations; urban motorway; Scottish Motorway.
"Motorway Permanent" Font
The typeface used on motorway ADS for road numbers. It is also available in "Motorway Temporary" flavour for use with black text on light backgrounds on temporary roadworks signs. See also Worboys, Transport Fonts.
Movements
Used in the context of describing an interchange or junction, 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.
Multiplex
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 - ie, 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 show the road as "M60 (M62)", with the M60 being 'dominant'.
N
National Speed Limit
The default speed limit which applies to 'derestricted' roads - ie, those 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 1970's oil crisis lowered to 50mph. Afterwards only dual carriageways were restored to 70mph, and single carriageway roads remain 60mph to this day. Can be abbreviated to NSL.
Natural Bypass
A road which provides a bypass for a settlement without being built as one - the route provides an alternative to driving through the town, but is not a road built or created for that purpose.
Nose
The tip of a merge or diverge. In American English, it's called a gore.
NSL
An abbreviation for National Speed Limit.
Number
Quite simply, the number a road has. Roads in the UK come in two basic types, classified and unclassified. If it's classified, that means it has a number, and its number will be prefixed by a letter - A, B or M. Road numbers provide a simple way to refer to a road and to describe a journey through the network. Each road number is unique through the network - though a different letter prefix means a different road. For example, there exist an A621, B621 and M621 and all are different roads in different parts of the country. See A-roads; B-roads; C-roads; motorway; Ax(M); unclassified; zones; "misplaced" number.
O
Odologist
Someone with an interest in roads. See Odology.
Odology
A very high brow way of saying 'the study of roads'. Derived from the Greek for 'road'. Guy Barry proposed two branches of odology, pure and applied.
Off-Ramp
An Americanised way of saying off-slip.
Off-Slip
A sliproad used to exit a road. See also on-slip.
One Way
A road that may only be used by traffic going in one direction only.
On-Line Improvement
An upgrade or other improvement to a road carried out on the existing road surface. Hence on-line dualling would involve turning the existing road into a dual carriageway, rather than building a new dual carriageway alongside. The latter would be parallel widening.
On-Ramp
An Americanised way of saying on-slip. Also appropriate on the M8 in Glasgow!
On-Slip
A sliproad used to get on to a road. Opposite of an off-slip.
Orbital
Another word for a ring road. 'Orbital' tends only to be used for very large or important ring roads - London's industrial-size ring road, the M25, is the original one. The term is often applied to the M60 also, and recently Blackburn has started signposting its own slightly less impressive ring road as an orbital too.
Overbridge
An alternative word for a flyover. Those striving for maximum variety in their description of highway structures might also like to use the word overpass sometimes.
Overpass
Another word to describe a flyover or overbridge, and clearly the opposite of an underpass.
P
Parallel Widening
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, I know, 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. See also symmetric widening; asymmetric widening.
Pedestrian
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.
Pedestrianise
Making a street available only to pedestrian traffic - a street which is only open to pedestrians (and often also bicycles and delivery vehicles during certain hours) is therefore 'pedestrianised'.
Pegasus Crossing
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 prevent them having to dismount. See also pelican crossing; puffin crossing; toucan crossing; zebra crossing.
Pelican Crossing
The name given to pedestrian crossings which use traffic lights to control motorised traffic. "Pelican" is an acronym of the name given to the crossings when they were first introduced in the 1960's - a 'PeLiCon' crossing, or Pedestrian Light Controlled crossing. See also pegasus crossing; puffin crossing; toucan crossing; zebra crossing.
Pinch Point
1. A place where a road is naturally constricted and has lower capacity.
2. A deliberate narrowing of the road or lane to reduce vehicle speeds.
Primary
Primary status is a special status that an A-road can have. Large towns, cities and places of 'traffic importance' across the country (like bridges or tunnels) are designated 'primary destinations'. The best routes between these places, by A-roads and motorways, are primary routes. Almost all motorways are de-facto primary routes. An A-road is rarely entirely primary; most either never have primary status or gain and lose it along the route. The upside of this is that navigating is simple if you follow the green signs; the downside is that it makes numbering complex since few primary routes follow just one A-road. In Scotland, all primary routes are also trunk roads.
Principal Road
This is not a strictly defined term; instead it tends to be a loose description of major roads.
Priority
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 traffic lights, where everything stops at one time or another: here priority means getting a longer green phase than other roads.
Puffin Crossing
A signalised 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. See also pegasus crossing; pelican crossing, toucan crossing, zebra crossing.
Pure
One of Guy Barry's suggested 'branches' of Odology - Pure and Applied - relating to the study of roads and road numbering without concern for, or relation to, practical use of roads. This could, for example, include plans for a renumbering of the whole system which would create a neatly numbered network. 'Pure' Odology could ignore the fact that this would cause massive disruption and confusion and cost a fortune.
Q
Queue
A British standard practice, both in a wider cultural sense and in a more specific roads sense. In British terms, a queue is what you encounter when you want to go somewhere.
R
Radial
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. See also bypass; arterial.
Ramp Metering
An American idea currently being trialled in Britain by the Highways Agency. Ramp Metering involves placing a set of traffic lights near the point where a motorway on-slip joins the main carriageway. 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 by not allowing large volumes of traffic to join the motorway at once. See also Mainline Metering.
Red Route
This term has any number of official and documented meanings.
1. A type of road found only in London, marked by special "red route" signs on entering one and with double red lines down the sides of the carriageway. No stopping for any reason is permitted on red routes (they are clearways in all but name), the idea being to keep traffic and especially buses flowing on principal roads. The A23 is an excellent example: as a vital radial route it is a red route, is heavily used by buses, and like most other red routes falls flat on its face because traffic spends most of its time stationary anyway. This policy has been successful in London and has recently been applied in smaller doses to Edinburgh, Glasgow and Birmingham.
2. Cycle/pedestrian route through Milton Keynes.
3. A rural road with a high accident rate in Lincolnshire, according to a recent campaign by the County Council there. Signs have been erected on roads like the A15 north of Lincoln to raise awareness of the likelihood of accidents on these routes.
Refuge
1. A traffic island in the centre of a road or dual carriageway, installed so pedestrians can cross the road in two parts rather than in one for safety reasons. Often the refuge itself is a gap between two closely spaced islands.
2. A gap in an extra-wide central reservation provided where long vehicles cross on a regular basis. The best example is on the A90 north of Dundee, where the refuge is itself a short length of dual carriageway.
Regulations
Rather than being the normal laws governing road use, the word 'regulations' tends to refer to motorway regulations. For those unfamiliar with the concept (like Americans or non-drivers), the following is a brief introduction. In legal terms, a motorway is not a public right of way or a public road - it is a "special road", meaning it is governed by section 19 of the 1984 Road Traffic Act. In real terms, 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. It also covers other things like a prohibition on stopping except in emergencies. See also motorway.
Relief Road
Often more a political word than a roads term. 'Relief road' is a pretty vague concept, though usually it refers to a road built to provide relief (by taking away most of the traffic) to another road. Very similar to 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 Bingley Relief Road which would be a bypass if it wasn't being built through the middle of Bingley.
Repeater
Repeaters are miniature speed limit signs placed at frequent intervals by the side of roads to reinforce a speed limit. They are required (in some cases legally) where an 'unusual' speed limit is applied - for example, on an NSL road which is in an urban area.
Ring Junction
The technical name for what is normally known as a Magic Roundabout.
Ring Road
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 American terms, a beltway. 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. In some cases called "circulars". See also orbital.
Roundabout
A type of junction common in Britain. Its main feature is a circular, one way roadway onto which all the roads meeting at the junction terminate. Traffic approaching the roundabout gives right of way to traffic already on it. It then circulates the roundabout until the road it wishes to exit on. In Britain roundabouts are always clockwise, but for right-hand driving the direction must be reversed. Contrary to popular belief, roundabouts have higher capacity and better safety records than traffic-light coordinated junctions, because of their self-regulating nature and the impossibility to 'run' one. Sometimes called "rotaries" in America. US readers should be aware that the British use of the word "roundabout" is much more flexible than in America. See roundabout interchange; magic roundabout; mini-roundabout; longabout.
Roundabout Interchange
A type of grade-separated junction that is truly British. See the interchanges page. See also roundabout.
S
Sabristi
The members of the SABRE Community. A term credited to the one-time member Viator. The singular forms are Sabristo (male) and Sabrista (female).
Safety Fence
Any type of fencing designed to stop traffic leaving a road or crossing onto a dangerous part of one (like into a lane of traffic going the other way). These come in a wide range of shapes and sizes.
Scottish Motorway
- 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).
- A standard dual two-lane motorway in Scotland, contrasting with the popular image of English motorways with three lanes in each direction.
- "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 driven as if a motorway.
Secret Motorway
Not to be confused with A-roads that simply have motorway characteristics, such as 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. However, crucially, even when such roads are special roads - most aren't - they still don't necessarily have motorway restrictions. 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!
Semi-Motorway
A road which is built to the standard (or very close to the standard) of a motorway, but isn't one.
Service Area
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 catering. Most are now pretty sophisticated affairs, with shops, restaurants and games arcades.
Signal Controlled
Anything that is controlled using traffic lights.
Single carriageway
A road which has one undivided carriageway for traffic, usually divided into one or more lanes for different directions of travel. See also dual-carriageway; single-track.
Single Track
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 the remote parts of Scotland, where even some trunk routes are still to this standard. See also single-carriageway.
Sleeping Policeman
A colloquial name for a speed bump - so called because, like a policeman, it makes sure you don't go too fast; and like a sleeping one it's laid out on the ground. See traffic calming.
Sliproad (or slip road)
Known in the US as 'on ramps' or 'off ramps'. A short one-way connecting road used for travelling between other roads, normally as part of a larger interchange.
Special Road
The legal term for a motorway - it is distinct from a public right of way, and must be expressly commissioned by the Secretary of State for Transport because it is a type of road unavailable to pedestrians, animals and so on. See regulations.
Speed Bump
Raised patches of road surface designed to slow traffic down. Abbreviated to "humps" on road signs. They come in several varieties, including "speed tables" (large bumps that extend over a length of road) and "speed cushions" (small bumps confined to one lane only, narrow enough that buses and emergency vehicles pass over unaffected). See also traffic calming.
Speed Limit
Every inch of road in Britain has a speed limit - a maximum 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.
Spur
A short road used to connect one road with another road or settlement. Any type of road can have a spur - B-roads, A-roads and motorways alike all have examples. All spurs must have a 'parent' road which they exist to serve. 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. Hence the M23 motorway 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 number.
Suicide Lane
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".
The suicide lane was once very common in Britain, particularly before motorways existed for most long-distance journeys. Many former trunk roads have two very wide lanes, where the road has simply been repainted from the original three lanes.
Superelevation
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. See also camber and crossfall.
Symmetric Widening
A technique used to widen a road which involves adding an equal amount onto each side of the existing road surface. See also asymmetric widening; parallel widening.
T
Taper
The place where a diverging or merging lane actually appears or disappears gradually. For a standard merge, the taper is the length of road between the tip of the merge nose and where the merging lanes disappear completely. For the end of an auxilliary lane, the taper is the distance between where the lane is at full width and where it disappears altogether. The taper length is usually determined from the nose angle of the merge or diverge, and the width of the merging or diverging lane(s).
Tiger-Tailing
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.
T-junction
The simplest three-way junction possible, where one road ends on another. Named because from above, it resembles a letter T. If this excited you, just wait until you see the crossroads.
Toll
A fee charged to motorists for using a road. Traditionally in Britain these only apply to privately run toll roads, or tunnels and bridges where the costs are repayed by the tolls. The new DBFO concept (where a private company maintains a road for the government) means that 'ghost tolls' are paid by the government for every vehicle using the road. The first DBFO road to charge a fee directly to motorists using toll booths across the road is the M6 Toll near Birmingham, which opened in late 2003.
Totso
A situation where a continuous route number exits a continuous road. Totso is an acronym that's pretty much self explanatory: it stands 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 doesn't retain one number.
Toucan Crossing
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. Very cheesy, I know. See also pegasus crossing; pelican crossing; puffin crossing; zebra crossing.
Traffic
Technically this term applies to anything that uses a road to move around, though usually it refers to motorised traffic (like cars, buses, lorries).
Traffic Calming
Where obstacles such as speed bumps, chicanes, ghost islands and mini-roundabouts are placed on roads with the intention to slow down traffic - hence 'traffic calming'. Frequently these measures are applied on roads thought to be used as 'rat-runs' (unofficial shortcuts) or as racetracks by 'joyriders' (youths driving stolen cars for fun). More often than not they provide a more exciting obstacle course for offenders, congestion on surrounding roads and a decrease in public faith in these measures to do anything more than delay road users (that's right, I don't like them).
Traffic Lights
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 also gyratory; pelican crossing; ramp metering.
Traffic Officer
An alternative term for HATO.
Traffic Signals
Another word for traffic lights.
"Transport" Fonts
The two fonts designed for use on motorways along with "Motorway Permanent". Adopted for use on all other road signs in the Worboys Report. There are two "Transport" fonts: "Transport Heavy" and "Transport Medium", designed by Jock Kinneir. The fonts are modified versions of "Aksidenz Grotesk", altered to improve clarity and readability.
Trumpet
A type of interchange used where one road terminates on another (ie, a three-way interchange). The most basic way to grade-separate a T-junction. See the Interchanges page.
Trunk Road
A road maintained directly by central government. All other roads are the responsibility of local authorities. Trunk road status is never relayed to road users - road numbers, signing, classification and primary status are all completely disconnected with trunk status. An attempt was made in Scotland to remove all non-trunk primary routes, but it failed and the two remain unrelated. See also detrunk.
U
Unclassified
A road which has no DfT classification - ie, one which is not part of the national numbering system. Unclassified roads may be given numbers by their respective highway authorities but these numbers are not for public use and should not appear on signs. See C-Road.
Underpass
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. See also overbridge and overpass.
Upgrade
An improvement to a road, almost always referring to a physical improvement such as widening the carriageway or rebuilding a junction. See also downgrade.
Urban Motorway
Just like a regular motorway, except it's built in an urban environment which means it is subject to lower design standards, with closely spaced exits and entries, narrow lanes, tight corners and frequently no hard shoulder.
Useless Multiplex
Or, if you like, "Useless" Multiplex. A specific type of multiplex where the signposted route in the multiplex ends during the length of the multiplex. Ironically, this is usually done because it's useful: see the A30/A303 multiplex, where the A303 ends rather than diverge from the A30 again. This is because it terminates on the M3, which makes more sense to motorists than a short section of A30 before joining the A303. Less useful is the A494/A550 multiplex, which you can work out for yourselves.
V
V-Road
Part of a road numbering system specific to the new town of Milton Keynes. Built on the American grid road system, 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".
Verge
The space along the side of the carriageway, when no footpath is present - usually grass but sometimes paved.
W
Weaving Section
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 the temporary lane and the main traffic lanes.
Worboys
In the early 1960's a government committee produced a document known as the Worboys Report (after the head of the committee) which made reccommendations for a new scheme of road signing. The scheme, which is still in use today, has become known as Worboys signing. See Llewellyn-Smith.
X
X-roads
A common abbreviation for crossroads.
Y
Yield
American for Give Way. Also appeared on a handful of very early Give Way signs, and Llewellyn Smith equivalents to Give Way.
Z
Zebra Crossing
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. See also pegasus crossing; pelican crossing; puffin crossing; toucan crossing.
Zones
The name usually used to refer to the nine areas of mainland Britain, divided by A-roads with single digit numbers, used as the basis for the road numbering system. Sometimes also called cones because most are triangular (sort of, if you use your imagination). See the Roads FAQ for a description of how the roads are numbered.
