Roads are generally understood to mean streets, roads and squares dedicated to public traffic. In particular, a street includes:
- the body of the road:
- Subgrade - the natural rock or soil on which the road body is built.
- Substructure - artificially produced dam body between subgrade and superstructure, not used in cuttings
- Superstructure - consists of one or more base courses and the road surface.
- Earthworks - dams, ditches, embankments, berms
- Structures - culverts, drainage systems, retaining walls, bridges, tunnels, noise protection systems
- Road surface - with road markings and signage
- hard shoulders and verges
- the airspace above the road body
- the accessories:
the official traffic signs, traffic facilities and other installations which serve the safety, order and ease of traffic and the protection of residents, e.g. delineators, lighting, traffic lights, crash barriers, road markings and planting
- the ancillary facilities:
the road maintenance depots, equipment yards, storage yards, deposition and extraction points, ancillary establishments and facilities
Legally, the entire public realm constitutes the road. For example, the term "cycling on the road" is misleading in that it includes the pavement. Pedestrians, cyclists and motor vehicles all move along the road.
Traffic Separation:
- motor vehicle traffic - it moves exclusively on the carriageway
- other vehicle traffic - on the carriageway or, in the case of bicycles, on the cycle path
- Pedestrians - On the sidewalk (if available), otherwise on the roadway.
Notation
Even after the 2006 spelling reform, only the spelling with "ß" is correct in Austria and Germany: "Straße". In many places you can find the wrong spelling "Strasse" according to both the current and the old rules. There, when using capital letters, "STRASSE" is correct.
In Switzerland and Liechtenstein, on the other hand, "road" is the correct term and is officially designated as such.
Components of the road cross-section
→ Main article: Road cross-section
A road cross-section should guarantee traffic safety without compromising performance, the objectives of environmental protection and urban development must be taken into account, and economic efficiency must be guaranteed.
Depending on the required function, the road cross-section is composed of the following elements:
- Roadway - divided into lanes and shoulder,
- Walking and cycling facilities, together or separately
- Parking areas
- hard shoulder
- Separation strips - divided into middle strips and side separation strips,
- Banquets
- Shelves and drainage channels
Building materials
The road surface is made of asphalt concrete, cement concrete, pavement or unpaved material (for example, crushed stone).
Traffic types and usage requirements
There are different uses for the traffic area, which is why different areas are established on roads. These include:
- Roadway
- verges, dividing strips, paved verges, verges,
- Bicycle paths and sidewalks,
- Stops, parking lots, parking bays and rest areas as well as the areas of traffic-calmed down areas.
The term paths is used to describe roads designed exclusively for non-motorised traffic. An exception here are the so-called rural roads. These are also designed for motorised traffic in agriculture and forestry.
In the area of roads and paths, a further distinction is made between the open road, the local road, the junction and the ancillary facilities.
Traffic capacity
The traffic capacity of a road depends to a large extent on its state of development (number and width of lanes, routing). In addition, town crossings with numerous junctions and intersections, railway crossings and the terrain topography (gradient/slope) also play a role. The share of truck traffic is also important. The higher the proportion, the lower the number of vehicles that can use the road in total without the traffic flow coming to a standstill. In Germany, two sets of rules define the construction standards for roads outside built-up areas. For motorways these are the Guidelines for the Construction of Motorways and for federal, state and local roads the Guidelines for the Construction of Rural Roads. They define the maximum capacity of a two-lane road at around 20,000 vehicles per day, although traffic congestion can already accumulate at traffic volumes above 10,000 vehicles per day - for example in intersections, with slow trucks and a lack of overtaking opportunities or at level crossings - and an expansion, e.g. in the 2+1 system or by converting intersections to height-free entrances/exits, can make sense. Two lanes per direction, a total of four lanes, are the standard for motorways and highly frequented sections of trunk roads with traffic densities of between 20,000 and 60,000 vehicles per day. Three lanes per direction (six lanes total) should be applied for traffic volumes between 60,000 and 100,000 vehicles per day, which applies to higher volume freeway segments. Traffic volumes above 100,000 vehicles per day only occur on the main motorways in conurbations and necessitate the creation of additional directional lanes.
Road categories
Roads are subdivided according to road categories.
These include, for example, motorways, trunk roads, main roads, local roads, access roads, play roads, agricultural and forestry roads, independently guided cycle paths, footpaths, roundabouts, tunnels or car parks. In localities, the distinction between through roads, urban roads, estate roads and residential roads is important. In Germany, the regulations of the Forschungsgesellschaft für Straßen- und Verkehrswesen (Research Society for Roads and Traffic) distinguish between main roads, collector roads and access roads in built-up areas, whereby this primarily designates the importance in the motor vehicle network.
Special categories are customs roads (duty-free roads), cul-de-sacs, one-way roads, pedestrian zones, temporarily closed or open roads, residential roads, bicycle roads, pass roads, race tracks.