The hierarchy of roads categorizes road

Road

A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...

s according to their functions and capacities. While sources differ on the exact nomenclature, the basic hierarchy

Hierarchy

A hierarchy is an arrangement of items in which the items are represented as being "above," "below," or "at the same level as" one another...

 comprises freeways, arterials, collectors, and local roads.

The related concept of access management

Access management

Access management, when used in traffic and traffic engineering circles, generally refers to the regulation of interchanges, intersections, driveways and median openings to a roadway. Its objectives are to enable access to land uses while maintaining roadway safety and mobility through controlling...

 aims to provide access to land development

Real estate

In general use, esp. North American, 'real estate' is taken to mean "Property consisting of land and the buildings on it, along with its natural resources such as crops, minerals, or water; immovable property of this nature; an interest vested in this; an item of real property; buildings or...

, while ensuring traffic flows freely and safely on surrounding roads.

Freeways

At the top of the hierarchy are limited access roads freeways or motorways, including most toll road

Toll road

A toll road is a privately or publicly built road for which a driver pays a toll for use. Structures for which tolls are charged include toll bridges and toll tunnels. Non-toll roads are financed using other sources of revenue, most typically fuel tax or general tax funds...

s. These roads provide largely uninterrupted travel, often using partial or full access control

Access control

Access control refers to exerting control over who can interact with a resource. Often but not always, this involves an authority, who does the controlling. The resource can be a given building, group of buildings, or computer-based information system...

, and are designed for high speeds. Some freeways have collector/distributor lanes (also known as local lanes) which further reduce the number of access ramps that directly interface with the freeway; rather, the freeway periodically interfaces with these parallel roadways, which themselves have multiple on and off-ramps. These allow the freeway to operate with less friction at an even higher speed and with higher flow. Often freeways are included in the next category, arterials.

Arterials

Arterials

Arterial road

An arterial road, or arterial thoroughfare, is a high-capacity urban road. The primary function of an arterial road is to deliver traffic from collector roads to freeways, and between urban centres at the highest level of service possible. As such, many arteries are limited-access roads, or feature...

 are major through roads that are expected to carry large volumes of traffic. Arterials are often divided into major and minor arterials, and rural and urban arterials.

In some places there are large divided roads with few or no driveways that cannot be called freeways because they have occasional at-grade intersections with traffic lights that stop traffic (expressways

Limited-access road

A limited-access road known by various terms worldwide, including limited-access highway, dual-carriageway and expressway, is a highway or arterial road for high-speed traffic which has many or most characteristics of a controlled-access highway , including limited or no access to adjacent...

 in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, dual carriageway

Dual carriageway

A dual carriageway is a class of highway with two carriageways for traffic travelling in opposite directions separated by a central reservation...

s in Britain

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

) or they are just too short (superarterials in Nevada

Nevada

Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

). Such roads are usually classified as arterials.

Frontage road

Frontage road

A frontage road is a non-limited access road running parallel to a higher-speed road, usually a freeway, and feeding it at appropriate points of access...

s are often used to reduce the conflict between the high-speed nature of an arterial and property access concerns.

Collectors

Collector

Collector road

A collector road or distributor road is a low to moderate-capacity road which serve to move traffic from local streets to arterial roads. Unlike arterials, collectors are also designed to provide access to residential properties...

s (not to be confused with collector/distributor roads, which reduce weaving on freeways), collect traffic from local roads, and distribute it to arterials. Traffic using a collector is usually going to or coming from somewhere nearby.

Local roads

At the bottom of the hierarchy are local street

Street

A street is a paved public thoroughfare in a built environment. It is a public parcel of land adjoining buildings in an urban context, on which people may freely assemble, interact, and move about. A street can be as simple as a level patch of dirt, but is more often paved with a hard, durable...

s and roads. These roads have the lowest speed limit, and carry low volumes of traffic. In some areas, these roads may be unpaved.

Motorway

Similar to freeways, these high-speed roads are designated with an M prefix or (M) suffix. e.g. M1, A1(M). The speed limit is generally 70 mi/h and there is a hard shoulder, an often slightly narrower lane next to lane 1, which is usually only to be used in cases of an emergency. Emergency telephones are located every mile along the route so motorists with broken-down vehicles can contact the authorities, although this is increasingly being done using mobile phone

Mobile phone

A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...

s. Signs are blue with white text for both destinations and motorway numbers. In general, junctions are given numbers which are displayed prominently, sometimes with a letter suffix, in a small black box on all the signs for any given junction. Junctions are generally signed one mile before they exit, with three or four further signs as the junction is reached, although on busy urban stretches this first warning can reduce to about ⅓mile. Cyclists, pedestrians, mopeds, very slow vehicles and certain other traffic is banned.

Primary A-road

Green on maps and signs. A main recommended route these can be either single carriageway or dual carriageway

Dual carriageway

A dual carriageway is a class of highway with two carriageways for traffic travelling in opposite directions separated by a central reservation...

. The primary road network is fully connected, meaning you can reach any part from any other without leaving the network. Some of the major dual carriageway primary routes have numbered junctions in the style of the Continental

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 semi-motorways. Many Primary Routes are largely or wholly subject to clearway

Clearway

The term clearway is used in several commonwealth countries to refer to stretches of road or street where parking is limited or prohibited.-Australia:...

 restrictions, and in major cities they may be classed as red route

Red route

Red routes are major roads in urban areas of the United Kingdom, on which vehicles are not permitted to stop. This includes stopping for loading or unloading, and boarding or alighting from a vehicle . Red routes are mainly used on major bus and commuting routes.Red routes are marked with red lines...

s. Emergency telephones, if present at all, are usually infrequent - there may be some additional telephones operated by the UK's two main motoring organisations, the RAC

RAC plc

RAC Limited is a breakdown company in the United Kingdom supplying products and services for motorists. Initially formed as the "Associate Section" of the Royal Automobile Club, it was incorporated as R.A.C. Motoring Services Ltd. in 1978. It was then sold by the members of the Royal Automobile...

 and the AA

The Automobile Association

The Automobile Association , a British motoring association founded in 1905 was demutualised in 1999 to become a private limited company which currently provides car insurance, driving lessons, breakdown cover, loans and motoring advice, and other services...

, but these are becoming rarer.

Non-primary A-road

Often exists where the route is important but there is a nearby primary route (A or motorway) which duplicates this road's function. Shown as red on maps, and has white signage with black lettering. Some non-Primary A-class roads are partially subject to clearway restrictions.

B road

Regional in nature and used to connect areas of lesser importance. Usually shown as brown or yellow on maps and have the same white signs as non-Primary A-Class routes.

C road

C roads are used as local authority designations for routes within their area for administrative purposes. These routes are not shown on road maps, but have occasionally been known to appear on road signs.

Unclassified

Unclassified roads are local roads with no defined destination. Local destinations may, however, be signed along them.

Autoroutes

Autoroutes of France

The Autoroute system in France consists largely of toll roads, except around large cities and in parts of the north. It is a network of worth of motorways. Autoroute destinations are shown in blue, while destinations reached through a combination of autoroutes are shown with an added autoroute logo...

Along with the rest of Europe, France has Motorways or Autoroutes similar to the British network. Unlike in the UK, the network is mostly accessible on payment of a toll, which is usually distance-dependent; there are generally more Toll (péage) Motorways in the South of France. However, sections passing through or close to major towns and cities are usually free. As in the UK, destinations reached via a motorway are shown with white text on a blue background. Junctions are usually numbered, the numbers being shown on signs in a small oval in the corner of the sign.

Route Nationale

Route nationale (France)

A route nationale, or simply nationale, is a trunk road in France. Trunk roads are in France are important roads which cross broad portions of the French territory, as opposed to secondary or communal roads who only serve local areas....

Before the building of the Autoroutes, the Routes Nationales were the highest classification of road. They are denoted by a route number beginning N, or occasionally, RN. Going back to a Napoleonic road classification system, these are main roads comparable with British Primary Routes. They are maintained directly by the state and are usually the shortest route between major centres. Many N-Class roads are dual carriageway for some or all of their length, with a few also being given the designation of semi-motorway, where junctions are grade-separated and there is a central reservation with crash barrier. The hard shoulder, or bande d'arrêt d'urgence, is often narrower than on full motorways and there are fewer emergency telephones.

Routes Départmentales

France (including overseas territory) is split into 100 Départments, the second-highest tier of local government, similar to a UK county or US state. The Départments have responsibility for all roads beginning with a letter D, or occasionally RD. These roads vary in quality, from newly built local dual carriageway

Dual carriageway

A dual carriageway is a class of highway with two carriageways for traffic travelling in opposite directions separated by a central reservation...

s and downgraded Routes Nationales to winding roads that are barely wide enough for traffic to pass. Generally, they are quieter than the Routes Nationales, and of a reasonable standard.

Routes Communales

In general, each settlement in France is a Commune - akin to a British Civil Parish. This most local level of government is responsible for maintaining all the local roads, which are numbered with a letter C prefix. Except in major towns and cities, where their numbers are usually not marked on signs, they are usually single-track and may be in a state of poor repair due to the large number of roads covered by populations as small as 10.

Romania

In Romania the roads are classified as:

• Autostrăzi (A) - Motorways
• Dumuri naționale și europene (DN, E) - National and European roads
• Dumuri naționale (DN) - National roads
• Dumuri județene (DJ) - County roads
• Dumuri comunale (DC) - Communal roads

Elsewhere in Europe

Most of Europe has adopted Motorways (Autoroutes/Autobahns/Autopistas/Autostrada), usually similar to those in France and the UK. The idea was originally developed in Germany, where all motorways are toll-free, and has spread widely. All major through routes in the EU

European Union

The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...

 and neighbouring countries have a European E-Road

International E-road network

The international E-road network is a numbering system for roads in Europe developed by the United Nations Economic Commission for Europe . The network is numbered from E 1 up and its roads cross national borders...

number in addition, or in the case of some countries' motorways, instead of a national number. In the UK these numbers are not displayed.

Otherwise, most other European countries have some form of differentiating between national routes, regional and inter-regional roads and other local routes.

External links

• FHWA - Functional Classification
• Florida Intrastate Highway System, an example of a statewide system of major arterials