Is expensive engineering the only way to improve road safety?

We all want safer roads and Toodyay Road has had a poor safety record. Indeed the much-stated mantra of Main Roads Western Australia (MRWA) is that Toodyay Road has the worst safety record of any road in the Wheatbelt. This was based on statistics that date back to the 5 year period leading up to 2015 when the Killed and Seriously Injured Index (KSI) was 0.74.

What is KSI?

KSI stands for Killed or Seriously Injured and is a standard metric for road safety. Seriously injured is defined as all hospital admissions for a minimum of 24hrs.

The formula is the total of KSIs divided by the length of the road (in our case, 27.1 Km ). These results are typically added together over a five year period.

At that time community group meetings with MRWA called for extensive improvements including more passing lanes in order to prevent the poor and potentially dangerous driving behaviour that results from being stuck behind slow-moving vehicles.

The calls for improvements to the road were undoubtedly justified because parts of the road remain in a terrible condition including broken and dangerous edges as a consequence of years of neglect.

But it is probably fair to say that those calling for major improvements had little concern, or more likely expectation of, the level of environmental destruction which is a consequence of MRWA delivering what it believes is optimal engineering but environmentally respectful solutions including those essential passing lanes. An example being east of Jingaling Brook Road.

Recently published data is interesting because it is of note that despite the road receiving no attention between 2015 and 2020 the latest KSI figure has fallen to 0.45 including only one fatality.

Of course, a KSI of 0.45 is not acceptable and road changes are required – the need for further reduction in the KSI is ongoing.

However, let’s not ignore the evidence of improvement and the fact that it is presumably attributable to factors other than expensive road engineering, namely campaigns and education devoted to encouraging better driver behaviour.

And let’s continue to look at the evidence of what are really the most cost-effective strategies to reduce major accidents. While acknowledging the need for some passing lanes, it is important to ask whether there are alternative ways to improve safety without clearing so much of the valuable environment?

Even if you don’t care about the loss of trees and vegetation you might have some concerns about how much money is being spent to improve safety through enormously expensive engineering solutions.

The good news is there is evidence that lower-cost solutions such as sealing the road shoulders have a dramatic impact on reducing the KSI level.

In the Austroads Guide to Road Design Part 31, a design manual for all road builders including presumably MRWA, it states: “It is noted that research in Queensland identified that rural undivided roads with little or no sealed shoulder (< 0.5 m category) had 1.7 times higher risk of casualty crashes (any type) than roads with 2.0 m sealed shoulders. Safety benefits of sealed shoulders were also evident on rural roads with lower speed limits e.g. 80 km/h (Austroads 2014b).

Closer to home is further supportive evidence for the value of sealed shoulders in a MRWA document which is a supplement2 to the Austroads document mentioned previously.

The MRWA has used an economic model to predict the impact of various engineering solutions on the KSI level based on data gathered from roads across Western Australia and based on likely traffic levels in 2031. This data is shown in the table below.

Type of Improvement Reduction in KSI Estimated Expenditure $ Net Savings
Do nothing +14% 0 -425 million
Austroads Cross Sections
(widening of carriageways)
12% 2,950 million -994 million
Low-cost option
(no widening but sealing shoulders)
61% 872 million 1278 million
Optimised Austroads Option
(widening of carriageway & sealing shoulders)
62% 3148 million 237 million

To summarise, the major findings from this model, as applied to various roads across the State and not just Toodyay Road, are that the low-cost option of just sealing the shoulders leads to almost the same reduction in KSI (61%) as does the much more expensive (and more environmentally destructive) solution of widening carriageways (62%).

This not only saves the environment, but taxpayers also end up paying far less and the funds can be directed to other worthy causes, such as education, health and policing – and we still get a much safer road. 

The MRWA response as to why such lower-cost options are not being used more is to say that they are not suitable for Toodyay Road because the community wanted passing lanes.

It seems, judging by this response, that the menu of engineering options is either low-cost or high-cost and nothing in between or not a combination of all of the above.

As we indicated earlier we at SASTR are not arguing for no passing lanes but we are questioning why, perhaps, do we need as many as are planned especially when it is clear that the road safety agenda could be addressed by less destructive and less expensive solutions.

It would of course be completely naive on our part to think that improvements to the road are just about road safety.

The bigger yet unspoken agenda is to make the road faster and eventually restore its whole length to a limit of 100 km/hour. There will be those in the community who will be entirely happy with this scenario although it is interesting to speculate what impact that will have on the KSI rate given that speed does undoubtedly kill.

But even for those of us who use the road all the time and experience the occasional frustrations of slow-moving vehicles, we don’t believe the level of destruction of the natural environment that is planned for further improvement is a satisfactory price to pay for saving a few minutes time.

A final view to consider here is that the environment is coming off second best to the need for economic stimulus.

We are reliably informed that even MRWA did not expect to get the funding for Toodyay Road, to deliver what are in places very expensive engineering solutions. But as part of the COVID  recovery governments of all persuasions place great store in spending money through road building which no doubt can be justified In many places.

We query the justification of spending tens of millions of dollars and the clearing of many hectares of beautiful and in some cases ancient native bush, to improve what we acknowledge is a problematic road junction but where there has not been a serious accident for decades.

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