Motorway

Motorway symbol in UK, France and Ireland. Similar symbols are used in some other countries.

A motorway (in the United Kingdom, Australia, New Zealand, Pakistan, some other Commonwealth nations and Ireland) is both a type of road and a classification or designation. Motorways are highways designed to carry a large volume of traffic where a normal road would not suffice or would be unsafe, usually between cities. In the UK they are predominantly dual-carriageway roads, usually with three lanes in each direction, although four-lane and two-lane carriageways are also common, and all have grade-separated access.

Equivalent terms in other countries include autoroute, Autobahn, freeway, autostrada, autopista,motorvej, autópálya, motorväg and autoput. In North America, the English terms freeway and expressway (including autoroutes) are used as a type of road, not necessarily as a classification type.

Regulations and features

A Sunday in April 2004 at 5 p.m. local time on Britain's busy M25

In Ireland and the UK, motorways are denoted by blue signage and an M-prefixed or suffixed road number. In New Zealand motorways were historically distinguished from other roads with green signage. This changed with the establishment of Transit New Zealand which extended the use of green signs to the entire state highway network.

The construction and surfacing of motorways is generally of a higher standard than conventional roads, and maintenance is carried out more frequently; in particular, motorways drain water very quickly to reduce hydroplaning. The road surface is generally tarmac ('black top') or concrete ('white top'). Other features are crash barriers, cat's eyes and increasingly, textured road markings (a similar concept to rumble-strips).

Common criteria

For a road to be classified as motorway a number of conditions must be fulfilled. The following conditions generally apply:
* Motorways must be accessed at junctions by slip roads off the sides of the main carriageway;
* Separate motorways are joined by link-roads at an interchange, the object of which is to allow traffic to change route without stopping or slowing significantly;
* Traffic lights are not permitted (except at toll booths and certain interchanges) - see Ramp meter;
* The start and end of a motorway must have signposted entry and exit points;
* Certain types of transport are banned, typically pedestrians, bicycles, learner drivers, horses, agricultural vehicles, underpowered vehicles (e.g. small scooters, invalid carriages). In the Republic of Ireland, the "Motorway Ahead" sign at every motorway junction lists the excluded classes of vehicles. The same is true for the "Motorway Entrance" sign on motorways in most Australian states.

In the UK and the Republic of Ireland there are further restrictions:
* The central reservation must remain unbroken (an exception being the Aston Expressway in Birmingham, which has none);
* Emergency telephones (which connect directly to the police) must be provided at a regular distance (In the UK emergency telephones are situated at intervals of 1 mile; Thus you are never more than 0.5 miles from one)

Note that these only apply to roads directly designated as motorways. Roads may also be indirectly designated as such, see Inheritance below.

A motorway in the UK, whether a motorway by design, or by inheritance must have a Statutory Instrument (SI) defining a stretch of road and sliproads as a special road under the Highways Act 1980.

Speed limits

Speed limits are generally higher than on ordinary roads. Some types of vehicle may be subject to a lower limit, while often sections of motorway are subject to lower speed limits due to local driving conditions.

Queues after an accident on Britain's M4

Motorways have an overall limit of 70 mph (113 km/h) for cars in the UK. The Conservative Party had proposed increasing the UK motorway speed limit to 80 mph (129 km/h), should they have gained power at the past election. Many road safety groups feel this would be a good idea, as it more closely represents the normal (and, they claim, safe) driving practice of the majority of motorway users. Roads in the Republic of Ireland have had metric speed limits since 20 January 2005 to conform to European convention and to existing directional signage, which has long shown metric distances. The new speed limit introduced for motorways is 120 km/h (75 mph). Previously a 70 mph speed limited applied, as in the UK.

In New Zealand the speed limit on motorways is fixed at the top limit for state highways, 100 km/h (62 mph). This rule is most in evidence in Wellington where Centennial Highway in the Ngauranga Gorge is not designated as a motorway because of the steep gradient, general usage and slow-speed junctions, despite leading directly into the Johnsonville-Porirua Motorway in the North and the Wellington Urban Motorway in the South.

Many other roads are of near-motorway quality, but are not classified as such (generally for breaking one or more of the above rules). These are referred to as dual carriageways, which in Britain usually have the same 70 mph (113 km/h) limit. The default limit for dual carriageways in New Zealand is 100 km/h (62 mph), in Australia it is 110 km/h, and in Ireland the default is 100 km/h on national roads and 80 km/h on other classes of road. Dual carriageways may be subject to a lower speed limit (e.g. in urban areas, or low-specification). In Ireland, high quality dual carriageways may also have a special limit of 120 km/h.

Lane usage

Diagram showing lanes and road layout, with Irish road markings.

White dashed lines denote the lane separation, while an unbroken white line is painted alongside the median (usually known as the 'central reservation'). A white line (or in the Republic of Ireland, a yellow line) on the edge of the slow lane marks the edge of the hard shoulder. The hard shoulder is not used for traffic and is reserved for breakdowns or emergency manoeuvres. Pedestrians should only use the hard shoulder to walk to emergency telephones and not for any other reason. Vehicles on the hard shoulder should activate their hazard warning lights.

Lanes closest to the edge of the road are intended for general driving – these are hence the "inside" lanes, while the lanes closest to the median are intended for overtaking (passing) slower-moving vehicles – hence they are termed "outside" lanes. Generally lanes closer to the centre of the road (outer lanes) are used for overtaking, while lanes near the edge of the road (inner lanes) are used for slower traffic (see diagram on right). Under the Highway Code in the UK, it is not permitted to overtake on the left, except in emergencies, when signs indicate drivers may do so, or when traffic is moving slowly. Similar rules apply in Germany and some other countries. With a touch of black humour, the practice is popularly known as undertaking.

Traffic should always use the lefthandmost lane possible. Generally this means a vehicle should use the lefthand lane next to the hard shoulder, and use the other two lanes only for overtaking manoeuvers, moving back into the left lane once they have passed the slower vehicle(s). In heavy traffic, it is acceptable to cruise in the middle lane to pass slower vehicles to avoid constant lane changes.

A significant problem on motorways is the 'middle lane hog', a driver who drives in the middle lane when there is no reason to do so. This can be very frustrating for other drivers. Faster vehicles approaching in the left hand lane have to manoeuvre across four lanes of the motorway rather than two to overtake such a vehicle, since undertaking is forbidden. Drivers of heavy goods vehicles can be especially frustrated by a middle lane hog, as their vehicles are not permitted to use the righthandmost lane on a three (or more) lane motorway under normal circumstances. Since undertaking is forbidden, a heavy goods vehicle cannot legally pass a slower moving vehicle in the centre lane.

In the UK lanes in a given direction are numbered from left to right as lane 1, lane 2, lane 3, etc. Lane 1 is the lane next to the hard shoulder.

Junctions

The most basic motorway junction is a two-lane flyover with four slip-roads, two on each side of the motorway, to exit or enter. A simple crossroads or roundabout is present on either end of the flyover. A rather large version of a roundabout, using two curved flyovers is sometimes used to present a single large junction for users of the slip-roads or crossing road. The slip roads leading off the motorway are known as 'exit sliproads', those leading onto the motorway as 'entry sliproads'. The precise sliproad at any junction may be identified by reference to the direction of the carriageway, for example 'northbound entry slip'.

The signal-controlled roundabout is often used in these situations and has become very common in Ireland. A far greater degree of complexity is present in Britain with varying types of Spaghetti Junction-style interchanges.

Motorway junctions are usually given a number, indicated in the UK and Republic of Ireland with a white number of a black background in the corner of signs approaching that junction. The same junction number is used in both directions on the motorway. Sometimes, where a junction is newly inserted between two existent junctions, it will be given a letter also (eg 2a ). In the Republic of Ireland, only the M50 and M4 use junction numbers consistently however, with some junctions of other motorways being numbered, and some not.

Location and construction

Major intercity or national routes are often built or upgraded to motorway standard. Motorways are also commonly used for ring roads around cities or bypasses of built-up areas.

In Britain there are plans to improve many motorways as well as to upgrade some roads to motorway status. In the Republic of Ireland, the National Roads Authority has been connecting main cities with motorways as part of a six-year National Development Plan. The European Union has part-funded many motorway projects in the past, as part of a Trans-European Transport Networks, and there are plans to invest billions of euro in such projects in the next ten years.

Toll charges for Britain's M6 Toll

One of the most recently constructed motorways in the UK is the M6 Toll, bypassing Birmingham and Wolverhampton, which opened in 2004 and is the only completely toll motorway in England. There are tolled sections of motorway on the M4 and M48, where they cross the River Severn at the Severn crossings. In the Republic of Ireland, the M1, M4, and M50 are all tolled, with sections of the M6, M7 and M8 likely to face tolls also in the future.

Inheritance

In the UK and Republic of Ireland, certain types of traffic are not permitted on motorways. Thus, to avoid people being forced to travel illegally, there are a number of rules about stretches of road which must be designated as motorways.

In all cases, there must be an escape route for traffic not wishing or not permitted to enter the motorway. As a result, the motorway technically begins as soon as the escape route has diverged from it; for example at a grade-separated junction, the motorway starts at the junction with the exiting slip road, and the opposite slip road is also part of the motorway for this and the following reason. The exception was the A1(M) near Leeds, which was "illegal", as pedestrians could legally cross 300 yards from the start, but cyclists and other types of traffic not permitted on motorways had no way of turning back. The escape route was the Boot & Shoe a mile before. This is remedied by the A1(M) extension. In some maps, the start was actually disguised or covered so people could not see the blunder.

As a result, this creates a less-restrictive set of rules for the standard of the road. Roads whose only destination is a motorway must be assigned motorway status, notwithstanding the possibility of them not being built to normal motorway standards. For example, the A48(M) motorway outside Cardiff begins after the last exit to St Mellons, since by staying on the dual carriageway you cannot get anywhere other than the M4 eastbound; however, the A48(M) is a motorway-grade highway. A similar example in the Republic of Ireland is the M6, currently a short 2 km section of the N6 road eastbound which leads exclusively to the M4 motorway. The equivalent westbound section of the N6 is not signed as a motorway however.

Route numbering

In the United Kingdom, motorways sometimes adopt the number of the nearest "A" road heading in broadly the same direction. However this is just for convenience, and about half of motorways don't bypass the A road with the same number - Motorways follow their own zonal pattern, similar to the A+B road zones, but with the boundaries formed by the 1-digit motorways (and various A roads where there are gaps), as opposed to the one-digit A roads (NB, the 4 zone seems to be hourglass shaped and motorways west of the M5 but south of the M4 have 4-zone numbers). The A road usually continues to also use that number, thus allowing both an "A1" road and "M1" motorway to exist as full complementary routes.

Signage on the N6 in the Republic of Ireland near Kinnegad, where the designation M6 is used for a short section of motorway.

In the Republic of Ireland, motorway and national road numbering does not follow the same convention. As of 2006, all motorways in the Republic are part of, or form, national primary roads. These routes are numbered in series, using numbers from 1 to 33 (and separately from the series - 50). Motorways use this route number (of the route they form part of) with an M prefix rather than N for national road (or in theory, rather than R for regional road) Roads Act 1993 (Classification of National Roads) Order 2006 (PDF) - Department of Transport. In most cases, the motorway has been built as a bypass of a road previously forming the national road (e.g. M7 bypassing roads previously forming the N7) - the bypassed roads are reclassified as regional roads, although updated signposting may not be provided for some time, and adherence to signage colour conventions is lax (regional roads have black-on-white directional signage, national routes use white-on-green).

The M50, an entirely new national road, is an exception to the normal inheritance process - as it does not replace a road previously carrying an "N" number. The M50 was nevertheless legislated as the "N50" route (despite having no non-motorway sections). The M50's designation was chosen as a recognisable unique number (As of 2005 N34 is the next unused national primary road designation). In theory, a motorway in Ireland could form part of a regional road Roads Act 1993 (Classification of Regional Roads) Order 2006 (PDF) - Department of Transport.

In Hungary, similarly to the Republic of Ireland, motorway numbers can be derived from the original national highway numbers (1-7), with an "M" prefix attached, eg. M7 is on the route of the old Highway No. 7 from Budapest towards Lake Balaton and Croatia. New motorways not following the original Budapest-centered radial highway system get numbers M8, M9, etc., or M0 in the case of the ringroad around Budapest.

Trivia

The first motorway ever built was the Autostrada dei laghi, inaugurated on September 21 1921 in Milan. It linked Milan to Varese. Piero Puricelli, the engineer who designed this new type of road, decided to cover the expenses by introducing a toll to be paid by whoever used the motorway.