Road Hierarchy

Road Classifications

The classification of the road hierarchy can be described as the grouping of individual roads, which forms a comprehensive road network. This is recognised through the function of each type of road. The Motorway is the highest level of the road hierarchy; it provides service at the greatest speed for the longest uninterrupted distance. The second highest road type is the arterial road; it has the similar function of providing high degree of mobility, but with some degree of access control. In comparison, collector roads provide a less highly developed level of service at a lower speed for shorter distances; it channels traffic from local roads to arterial roads. Lastly, local road consists of all roads not defined as arterials or collectors, as it provides access to land with little or no through movement (U.S. Department of Transportation, 1997). Furthermore, there is a trade-off between arterial and local roads, because arterial roads attempt to achieve greatest mobility, and local roads attempt to achieve greatest accessibility, if one increased, the other one decreases.

The concept of road classifications in relation to the level of service was introduced to measure the desirable level of road service, and it was a major advance in deterring the variable character of roads based on the relationship between traffic needs and adjoining land uses, it is a study of physical form of the road rather than principally (Pringle, 1971). The concept has implemented in the road hierarchy, as motorway and arterial roads provide great mobility to outside communities; collector roads around big blocks, it balances between mobility and access; and local roads provide service lanes for direct access to building. In the content of figure 1, primary distributors are arterial roads; secondary distributors are collector roads; and local distributors are local roads.

Suggestion:

Auckland has the highest proportion of car use and lowest use of other transport modes, and also lowest use of public transport usage. In about one car per two people, this leads to negative environmental impact, as transport emission contributes two million tons of CO2 each year to Auckland’s air pollution (Hucker, 2000).Therefore the primary role for the Auckland Transport Authority is to develop strategies to encourage public to participate on the usage of public transports, as it would reduce traffic congestion and also reduce number of vehicles on road. This can be achieved by using effective road network to maximise traffic movement.

Hucker, B. (2000) Auckland Issues and Central Government, Unpublished paper prepared for the Minister of Local Government, the Hon. Sandra Lee.

Pringle, D. (1971) The Road Network Land Use Relationship, Auckland: Auckland Regional Authority.

U.S. Department of Transport. (1997) Flexibility in Highway Design, http://www.fhwa.dot.gov/environment/flex/ch03.htm, (accessed: 30/09/09).