First, some background, Australia has a population of over 22 million people, with five cities which have a population of over 1 million. The country is divided into six states and two major territories (which are similar to states). There are around 815,000 km of roads, of which about 80% are rural.
We can look at road hierarchy in terms of the strategic road network, then at examples of classification at national, state and city level.
Strategic road network
This phrase could be used to refer to the road links in the National Land Transport Network. This is “a single integrated network of land transport linkages of strategic national importance, which is funded by Federal, State and Territory Governments. The National Network is based on national and inter-regional transport corridors including connections through urban areas, links to ports and airports, rail, road and intermodal connections that together are of critical importance to national and regional economic growth development and connectivity” (see link).
National road classifications
In 1989, Australia’s National Association of Australian State Road Authorities (NAASRA – now known as Austroads) introduced a road classification system. It had nine classes (see link). Rather than having a descriptive name such as “main arterial” the different classes were simply numbered (see following table). An ARRB research report published in 2001 (ref. 355) introduced a further set of sub-classes for low-volume rural roads, and suggested appropriate geometric design standards for each sub-class.
In 2007 Australia’s National Transport Commission produced a report (ref. 335) which detailed a performance-based method of classifying roads for heavy vehicles. The classification is related to access for vehicles of larger and larger size:
- Level 1 access – passenger cars to single articulated
- Level 2 access
- Level 3 access
- Level 4 access – triple road train (type II) – note: this vehicle type has a length of 53.4m
State road classifications
In 2008 the State of South Australia (population 1.6 million) produced guidelines on road classification (ref. 243) which would ” be based purely on whether the road is arterial or local. that is, the …. intended focus is to determine if a road is the responsibility of state or local government. Any subsequent hierarchy (such as the functional classes or other categorisation) would be up to each road authority (eg council) to apply to their roads, to the extent they consider appropriate”. The reference gives the following structure:
- Rural roads
- Rural arterial road
- Rural local road
- Urban roads
- Urban arterial road
- Urban local road
The State says it has started to use role and function maps in determining the hierarchy of its arterial roads. These maps appear to be network plans for different types of traffic and purpose, and include commuter routes, regional bus routes and cycle routes.
In the State of Western Australia (population 2.4 million), road classification (ref. 354) is:
- Rotaries (roundabouts)
- Main roads
- Secondary roads
- Unclassified roads
Western Australlia identifies ramps and larger roundabouts as individual highways.
For each classification, the document includes tables of values for features such as lane width. For example, for a kerb-side lane on a two-way undivided town road with a speed limit of 60 to 70 km/hr the minimum lane width is 3.2m (for class 1 access) and 3.6m (for class 4 access).
City road classifications
Brisbane is the third largest city in Australia. Its metropolitan area covers a population of 2.15 million (wikipedia) which is about a tenth of the total population of the country. Brisbane currently (February 2013) has an online version of a draft new City Plan (link) . The plan is interesting – for example because it clearly refers to networks, and to networks for different types of road traffic; and also because it is very detailed. The online documentation includes network plans (see example in fig. 1) and even typical design details and cross-sections for various types of street element – these alone are worth a visit.
Chapter 2 of the “eplan” discusses movement networks, and specifically for:
- Road hierarchy
- Freight hierarchy
- Bicycle network
- Streetscape hierarchy
A number of design parameters are specified for the various levels of the each hierarchy. For roads these include speed (posted speed limit), a minimum design vehicle and streetscape.
Fig.1 : Excerpt from part of Brisbane’s draft bicycle network
A national road classification for Australia?
Australia does not yet appear to have a national road hierarchy or classification. Writing in 2012, Lauchlan McIntosh (ref. 360) quotes Wegman (ref. 361) and adds some comments of his own:
“Wegman suggests a Functional Road Classification and Hierarchy for South Australia which endorses a framework for establishing credible speed limits (….). Any such program should be national, just as vehicle safety assessment, education and enforcement. These programs should not be constrained by state borders”.
In another example, in 2006 the ICSM roads working group produced a report on “assessing the feasibility of a national road classification” (ref. 334). The document gives an explanation of the difference between a functional road hierarchy, an administrative road hierarchy and a structural road hierarchy (the latter is determined by highway geometrics). Its recommendations included for
“a cooperative approach between all levels of government (to agree) to implement a mutually acceptable national road classification system”.
“The development of a road hierarchy must be scaleless, such that the same classification system applies irrespective of the scale at which the classification is being interrogated . Too often road hierarchies are modified to include localised or regional significance which reduces the overall effectiveness of the hierarchy in a State-wide or national sense”.
Some interesting points from a review of material on road hierarchy and classification in Australia:
- The country has several different road hierarchies. Few refer to all levels of the road system
- A number of documents sensibly refer to road networks for different users. Indeed, every road hierarchy should begin with a definition of a road network – or even better, first with a definition of road users (each of which will then have a road network defined for it).
- There is sometimes an inconsistent use of terminology.
- The references relate very many parameters to road classification. In other words, once someone has selected a classification (or road hierarchy) for a road he has set many of the design features of the road. For example, George Gummarra in (ref. 355) relates his recommended classes for low volume roads to geometric design guidelines, and points out that design speed is one of the most important features in arriving at these.
We can apply this generally to a road hierarchy / classification to suggest that:
For a road classification for motorised transport there are fewer than 16 possible categories. These are strongly related to design speed so that once a category in a road hierarchy has been selected, parameters such as design speed, highway geometry, streetscape, cross-section and even “place” have also been selected.
Thanks to Harry Audus of Brisbane City Council for pointing out the Brisbane city website.
243 – Government of South Australia and LGA of South Australia, “Road classification guidelines in South Australia” (2008)
334 – ICSM, “Assessing the feasibility of a national road classification” (2006)
335 – NTC, “Performance-based standards scheme, network classification guidelines” (2007)
354 – State of Western Australia, “Road Classification in Western Australia” (current download)
355 – ARRB, AR354 “Road classifications, geometric designs and maintenance standards for low volume roads” (2001)
360 – Lauchlan McIntosh, “Road safety management in Australia” (from Roads Australia, published November 2012)
361 – Professor Fred Wegman, “Driving down the road toll by building a safe system” (Government of South Australia 2012)