During the Easter holidays, dozens of student drivers hit the road, with parents carefully recording all their driving hours. Many of us have been through this process, either as a student, supervisor, or both.
The requirement is particularly high in New South Wales and Victoria, where learners must complete a minimum of 120 hours of supervised driving before being allowed to drive unsupervised. This is one of the highest requirements for learner drivers in the world.
We wanted to answer whether this supervised driving practice actually produces safer drivers.
Our study evaluated the effect of two significant increases in the minimum mandate for supervised driving hours in New South Wales: the 2000 reform from zero to 50 hours and the 2007 reform from 50 to 120 hours.
Read more: There’s little to gain and a lot to lose in lowering the minimum driving age
What we found
By comparing people who turned 16 – the minimum age to get a learner’s permit – just before the policy changed with people who turned 16 just after, we were able to isolate the effect of these policy changes on motor vehicle crashes, while abstracting from other factors that can influence accidents.
Our data set included all license and crash records in New South Wales during the reform periods. The accident data includes all serious accidents – leading to hospitalization and/or towing of a vehicle.
Think of people born in July 1991 or later. They were under the 120-hour mandate. But those born slightly earlier fell under the 50-hour mandate if they got their learning permit relatively quickly.
If the policy were effective, we would expect a sharp drop in crash rates for people who turned 16 after the 120-hour rule came into effect. But we found that there was no decline.
We analyzed the data in several ways, all of which suggested that the 2007 reform had no effect on accident rates. Due to our large sample size, we were confidently able to exclude meaningful effects. We did observe a slight delay in the average age for obtaining a provisional driving license (P1) of about a month.
The first policy change, on the other hand, was effective. We found that increasing supervision from zero to 50 hours reduced the chance of a motor vehicle accident in the first year of unsupervised driving from 6.9 to 5.4 percentage points, a reduction of 21%. However, there was no reduction in the risk of an accident after this 12-month period, suggesting that the additional experience is useful initially, but does not change driving behavior in the long run.
Since young men are at a higher risk of crashing than women, we thought there might be gender differences. In fact, the results were very similar for men and women.
It is important to note that we have reviewed the policy mandate, but we cannot guarantee compliance with it. In practice, people can work more hours than required, or report too many hours, putting them at risk of fines if caught. Widespread non-compliance could undermine the effect of the mandate. Available proof suggests drivers in Australia are largely truthful in their reporting.
Mick Tsikas/AAP
Why is this important?
Motor vehicle accidents are the second leading cause of death for people aged 15-24 in Australia. Many policy measures are aimed at reducing the risk for young drivers, including the introduction of certified driver’s license and associated features such as provisional speed limits, passenger restrictions, and engine restrictions.
Minimum supervised driving hours are a potentially important tool to improve road safety, but have so far not been subject to a thorough evaluation. Evaluating this policy is important as there are costs associated with the mandate.
The obvious price is the time of students and tutors. However, there may also be other social costs. By creating barriers to obtaining a permit, such policies could, for example, limit young people’s access to work and education, and entrench the disadvantage, particularly for those from single-parent and low-income families, or those who leave home have gone out and do not have access to a licensed driver.
Read more: What parents need to know about learner drivers: four important lessons
How many hours should the mandate be?
Our findings suggest that there are benefits to guided driving experience. Moving from a zero hour to 50 hour regimen significantly reduced the risk of motor vehicle accidents. But the move from a 50 to 120 hour regimen yielded no further benefits, suggesting that benefits are diminishing and that the mandate in New South Wales may be too high.
Like us, you may be wondering where the 120-hour figure comes from. We’re not sure, but a review from 2011 by the Auditor General of NSW notes a Swedish study. A group of young drivers who reported having practiced for 118 hours had a 35% lower crash risk than those who had practiced between 41 and 47 hours.
The problem is that it is difficult to attribute this difference in accident risk to the difference in reported hours, because the two groups of drivers were fundamentally different, self-selected for different policy regimes and also experienced other policy differences. The first group in particular was allowed to start driving 1.5 years earlier than the last group.
Where possible, policy changes should be based on high-quality empirical evidence and subject to rigorous evaluation after implementation. Teenagers in New South Wales have been tracking their driving times for nearly 25 years, but with little evidence on the benefits, until now.
Our results call for a reconsideration of the number of hours learners are required to complete, and suggest exploring other avenues for further improvements in young driver safety.
