Access Roads

Form and Function

The width of access roads varies depending on context. However, a functional width of 18 feet (5.5 meters) for two-way and 11 feet (3 meters) for one-way vehicle flows is appropriate. Added width may be required depending on the types of vehicles that will use the road: wider carriageway is necessary in industrial areas. Depending on carriageway width, two-way roads may permit two vehicles traveling in opposite directions to pass. Narrower access roads have to function as yield streets, requiring passing areas. Passing areas are usually facilitated through intermittent gaps in on-street parking.

The use of a road by a particular mode of transport depends on the functional hierarchy, urban location, and land use situated along the road. Access roads are often intended to facilitate use by a variety of transport modes, with particular emphasis on pedestrian activity. It can be expected that more pedestrian activity will occur within residential land use cells (particularly where shops and open space are accessible locally) than within nonresidential (that is, industrial) precincts. Despite this expectation of use by pedestrians, many residential access roads have been constructed without footpaths, or sidewalks. This can create difficulties for all potential pedestrians and particular problems [Page 2]for the mobility and visually impaired. The lack of pedestrian facilities along access roads can reflect low anticipated walking demand.

A series of narrow access roads, enhanced by landscaping and several small- and medium-sized roundabouts, surround this shopping center and its parking lot in Málaga in southern Spain. Roundabouts, often seen on busier access roads, may serve dual purposes of both managing vehicle movements on different approaches and fostering traffic calming.

Aside from footpaths in some circumstances, access roads rarely incorporate specific design responses in support of facilities for pedestrians, cyclists, or public transport. This is because access roads represent the bottom rung in a road hierarchy and, in theory, attract relatively low traffic volumes at relatively slow speeds. Cyclists are expected to use the carriageway, while transit services are more likely to use higher order roads rather than access roads except for short distances. Moreover, the carriageway width and swept paths required by buses can compromise objectives relating to safety and speed mitigation, thereby adding to the case for transit to be routed via higher order roads.

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