Myth: Freeways are safer than arterial roads

Myth: Freeways are safer than arterial roads
Fact: Some freeways are safer, others are more dangerous. In any case, building freeways increases the volume of traffic on nearby arterial roads, which experience greater trauma as a result. When the effects on the wider road network are considered, there is no compelling evidence for a reduction in crash rates, and some evidence for an increase.

Faced with a lack of evidence for congestion reduction or economic benefits from freeways, the road lobby often falls back on the argument that building freeways makes the road system safer. Freeways are safer than ordinary arterial roads, they argue, because they have a lower crash rate per vehicle kilometre. Build more freeways, get fewer crashes!

This argument is at best misleading and at worst false. There is no shortage of evidence for the contrary view, that freeway-building doesn’t reduce crash rates at all. According to Vicroads statistics, one of Victoria’s worst ‘black spots’ is the stretch of the Monash Freeway in East Malvern, where 54 people died between 1999 and 2004. And despite all the freeway-building that occurred in the decade between 1992 and 2002, Victoria’s road toll merely bobbed up and down around an average of 400 a year, with no discernable downward trend at all over that period.

Starting in 2009, the Transport Accident Commission has published a breakdown of road fatality statistics by council area. These shed some interesting light on the link (or rather lack thereof) between freeways and road safety:

  • Ten Melbourne municipalities have at least two motorways within or bordering their council area (Boroondara, Brimbank, Casey, Frankston, Greater Dandenong, Hume, Melbourne, Moreland, Whittlesea and Yarra). The mean number of fatalities recorded in these municipalities was 5.7 in 2009 and 6.1 in 2010. The remaining 21 councils had an average of 4.0 road fatalities in 2009 and 3.2 in 2010.
  • The municipalities that are bisected by motorways (and therefore have better access to motorways from a greater proportion of locations) had on average 5.9 road fatalities in 2009 and 4.9 in 2010. On the other hand, those with no motorways, or motorways just bordering their council areas, had 3.7 road fatalities on average in 2009 and 3.4 in 2010.

While there are many factors that account for differences in road fatality rates, it is notable that in both these examples, the difference in mean fatality rates is more than large enough to be statistically significant.

Freeways fail to improve safety for the same reason they fail to reduce pollution: by encouraging people to drive further, drive more often and use other modes of transport less, they increase the overall level of traffic and hence people’s risk of being in a crash. A freeway might be safer than an arterial road if it carried the same amount of traffic, but of course the whole point of freeways is that they increase the amount of traffic – so any inherent safety benefits are cancelled out by growth in traffic volumes.

Two other black spots in Victoria with a notorious reputation for crashes are Springvale Junction and Victoria Parade / Hoddle Street, with 112 and 61 fatalities respectively between 1999 and 2004. These point to the second reason freeways don’t make the road system safer. Most people’s journeys don’t start or end on freeways, so people still have to navigate the arterial road network before they get onto the freeway and after they get off. As the huge volumes of traffic generated by the freeway spill out onto the arterial road network, they increase the number of crashes occuring on arterial roads. Hoddle Street is a black spot not because of any great design flaw with Hoddle Street, but because it is the principal access route to the Eastern Freeway.

Official forecasts for new road projects also suggest that they are likely to increase, not reduce, crash rates in the general area – even on adjacent freeways. For example, a ‘Transport Impact Assessment’ for the West Gate Tunnel Environment Effects Statement in August 2017 forecast that as a result of building this road, crashes in the M1 corridor (including on the West Gate Bridge) would increase from 61 to 117 a year by 2031. A consultant for the road authority commented to the assessment panel as follows:

I suspect the difference is there is a more substantive freeway network which the project delivers so there’s a greater chance — or possibility — that there would be an incident.

—John Kiriakidis (GTA Consultants) as quoted in a Herald Sun report

Trains, trams and buses are inherently safer than cars to travel in; statistics show that you are at least 10 times less likely to suffer a serious injury travelling by public transport than covering the same distance in a car. Freeway building, by encouraging a massive growth in car travel at the expense of public transport, exposes more people to higher risk and makes the transport system as a whole less safe.

In a common variation on this myth, the road lobby likes to point to the lower road toll per capita in Germany, a country generously provided with non-speed-restricted autobahns. It is certainly true that, according to the OECD’s International Road Traffic and Accident Database (IRTAD), Germany’s road toll of 5.1 per 100,000 population is lower than Australia’s road toll of 6.7 per 100,000 population. But until recently, this merely reflected the fact that Germans do not drive as much as we do (even though they own just as many cars). In 2001, for example, the IRTAD figures for deaths per billion vehicle kilometres (a better measure of actual exposure risk) told the opposite story from the per-capita figures: Germany’s toll of 11.3 per billion veh-km actually exceeded Australia’s toll of 9.1 per billion veh-km. Only more recently has Germany improved relative to Australia on this score: in the decade from 2000 to 2010 Germany slashed its road toll by 45%, while Australia only managed an 18% reduction. But Germany achieved this primarily through traffic calming and speed-limit reductions in urban areas, not by expanding its autobahns. Though Australia built many more freeways over this decade than Germany did, it failed to reduce its road toll by anywhere near the same percentage.

As road safety expert Bruce Corben told The Age at the beginning of 2012 when it was revealed the road toll in Victoria had not decreased from the preceding year, the countries with the lowest fatality risk (whether per person or per vehicle kilometre) are the Scandinavian countries, the Netherlands and Britain. What all these countries have in common is high use of public transport, walking and cycling, along with road safety policies that focus on driver behaviour rather than expansion of limited-access roads.

In summary, empirical evidence both from Melbourne and overseas confirms that road-building leads to higher traffic volumes and hence more crashes, while on the other hand countries with higher public transport use than Australia tend to have a lower per-capita road toll as well.

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Last modified: 24 August 2017