The theory of road classification puts motorways and other arterial roads at the first level; and human nature being what it is, the first level is automatically assumed to be the most important level. Yet this doesn’t make sense. Motorways and similar roads are intended for long-distance travel – as compared with residential streets (for example) which are designed for short distance travel. There are two problems here:
- Very few people make long distance trips, and
- Most long-distance trips (indeed, most trips) begin or end at the home – so that most trips use a residential street.
– So perhaps streets should be the most important level in a road hiearchy.
Few long-distance trips
In the USA,
- most vehicle trips are less than 6 miles long, around 85% are less than 15 miles and 95% are less than 30 miles long (from a chart prepared by the US Department of Energy, here )
- in 2009 the average vehicle trip length for trips to or from work was 12.2 miles, and for all trip purposes was 9.7 miles (ref. 565 table 6)
In the UK
- In the period 1991-2001, the average distance people travelled to work was 8.5 miles, whilst the average distance for leisure and shopping trips was 6.8 miles (ref. 563)
Most trips are home-based trips
Here a home-based trip is defined as one which either starts or ends at the home. The USA’s National Household Travel Survey 2009 indicated that around 68% of all trips are home-based trips. Probably, most homes adjoin a residential street.
If most trips start or end in a residential street (or similar lower class road) and few trips need to use a motorway (because they are less than 15 miles or so) then it would seem that the most important road class is that for residential streets; that the importance of motorways is perhaps over-rated; and that if any class of road is to be well maintained, it should be residential streets. This is not necessarily the case in practice. For New Zealand for example (see here) there are about 8 times as many km of local roads than there are state highways, whilst the expenditure on local roads is only 1.8 times that of the expenditure on state highways.
Meanwhile the condition of roads in some countries leaves much to be desired. In 2012 the UK newspaper “The Guardian” had an article headed “UK roads at crisis point as potholes multiply” (I suspect that these roads do not include motorways but did include streets). There is even a website (Mr. Pothole) dedicated to a campaign against potholes in roads.
Maybe motorways are not so important after all – and if so, a country with limited funds should stop spending money on building more of them and instead spend the funds on maintaining existing roads and streets.
563 – UK, Managing our roads; July 2003
565 – USA, FHWA “2009 national household travel survey” (2011)