20 May, 2020   By: Ruth Callaghan

Right now, the daily commute and congested roads are a distant memory and it's unlikely freeway congestion is on the list of 'normal' things we miss.

But the same busy roads will be there when offices and workplaces reopen and with them the frustrations of being trapped in traffic for roughly an hour a day.

According to the 2019 Household, Income and Labour Dynamics in Australia Survey, between 2002 and 2017 the average commuting times for Perth workers increased 10 minutes to 59.3 minutes a day.

As we near the 60-minute mark for our daily commute, we will begin testing the limits of a theory known as Marchetti's Constant.

Throughout history, argued Italian physicist Cesare Marchetti in 1994, people have been willing to spend about half an hour commuting to or from whatever work they do.

From the centre of ancient cities to their walls, the radius was rarely more than 2.5 kilometres - about half an hour's passage - while historic villages in places like Greece tended to be spaced 2.5 kilometres apart.

Marchetti's Constant has been used to understand the demands on urban planning. If the time we're willing to spend commuting is constant, but the speed of our transportation increases, the urban footprint can cover a wider area.

Walking might cover 2.5 kilometres in half an hour but a bus can cover 10 kilometres in that time, a train about 20 kilometres and a private car 30 kilometres, so cities have grown and expanded in line with the efficiency of transport on offer.

The problem comes once the population grows. Without better planning to improve access to local jobs and a shift away from solo car travel, the daily commute slows and becomes greater than that half hour.

In that case, Marchetti's Constant is sometimes used to argue one of the causes of bad driver behaviour - suggesting that once we hit the 30-minutes limit, our nerves begin to fray.

Image of traffic on Perth freeway 

How frustration builds

Bad driving and inconsiderate behaviour which can spill over into anger, have all been linked to the amount of time that we're stuck in traffic.

"There are a lot of sources of road user frustration, and long commutes and delays caused by heavy traffic certainly play a part, as well as things that might not even have anything to do with using the road," says Sarah Macaulay, Senior Manager of Public Policy at RAC.

"There's research to show that our mental state can impact how we drive - whether we're angry about something else, annoyed by daily hassles or upset - so we need to be aware of how we're feeling before we jump in a car and drive.

"We also receive feedback from drivers, cyclists and pedestrians alike that other road users can make them feel less confident and even intimidated when sharing the roads, which can contribute to frustrations and unsafe behaviours.

A study published by the Monash University Accident Research Centre last year found almost all drivers confessed to what might be called 'minor' aggressive behaviours, such as expressing annoyance (reported by 60 per cent) and sounding the horn in anger (70 per cent).

More than 40 per cent reported that they had infrequently or occasionally followed a driver who was the target of their frustration so closely that it would be difficult to stop in emergency.

A remarkable 30 per cent said they would chase another driver in anger, and one per cent of drivers said they would do both on a regular basis.

Image of cars close together

Frustration on a hair trigger

The triggers for frustration can be a mixture of internal and external factors. The age, gender, personality and beliefs of drivers have all been linked to driver aggression by researchers, as have factors like the presence of road works or even outside temperature.

But there is also 'contagious discourtesy', in which actions by others on the road are perceived as being a personal affront, prompting discourtesy in return.

Queensland University researchers have found that they way drivers interpret events can also have an impact, including personalising discourteous driving ("they cut me off on purpose"), catastrophising ("they could have killed me!"), and overgeneralising ("people are hopeless drivers").


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The researchers also found that road anger could be defused if drivers remembered the 'common humanity' of everyone on the road and tried to be more forgiving.

"When you're in your vehicle, it can seem like you're in your own environment, somewhat separated from others," Macaulay says.

"People's behaviours can change a little on the road and social norms can seemingly vanish.

"We need to be conscious of others around us, particularly vulnerable road users who are at greater risk in a crash, so we're sharing that road space safely."

To avoid frustration, Macaulay says it is important that every road user thinks about the impact of their behaviour on others.

"Following the road rules is fundamental, and a bit of courtesy can also go a long way in improving the journey experiences of all road users," she says.

"If we're weaving in and out of traffic, not giving other drivers and cyclists enough space or warning, we can cause a lot of frustration for other road users."

Image of person using car horn

Etiquette is more than common sense

So, what are some of the common written and unwritten rules of the road that can reduce the level of angst among drivers?

Merging is a key point of frustration, according to RAC members. A 2017 survey found almost half believed other drivers don't know how to merge properly.

Clashes frequently occur where cars otherwise separated by a dotted lane line need to go from two lanes to one.

Australian laws require that where both lanes end and become one, the car that is in front has the right of way.

Rather than rushing to be the driver ahead when approaching the merge point, good driving etiquette can smooth the merging experience.

Merging drivers should indicate early, keep a safe distance between their vehicle and the one merging in front of them, and try to match the legal speed of the road or the other vehicles if slower, to reduce the risk of a collision.

When one lane ends, like on the freeway and highway on-ramps, the driver in the continuing lane has right of way. The driver changing lanes should try to get up to speed with traffic on the freeway or highway, indicate their intention to join the lane and move into the gap at the earliest and safest opportunity.

A quick wave to acknowledge the efforts of the other driver once you're safely in the lane won't hurt as well.

RELATED: The art of Perth's traffic flow »

Image of merge sign

Tailgating, or driving too close to the car in front, is another sure-fire cause of frustration. After speeding and failure to indicate, tailgating was the third most common road rule RAC survey respondents said they saw other drivers breaking. And it's risky as well, as it can lead to rear-end crashes.

RAC recommends applying the two-second rule, which represents the minimum time that should elapse between vehicles passing the same point on the road.

It's essential to remember though as driving conditions change, that time and therefore the distance needs to increase. Providing extra space in rainy, dark or wet conditions and on high speed roads is more considerate as well.

The two-second rule will also not help if you are not alert. At 60 kilometres an hour an alert driver will travel 25 metres in the 1.5 seconds they take to react, and another 20 metres once the brakes are applied. A driver who is not alert will travel much further.

Another common source of frustration that links back to congestion is the habit some drivers have of blocking side streets and intersections, preventing traffic from moving through and creating queues. This issue spikes during peak periods, and the risk of gridlock increases.

WA's Road Traffic Code requires drivers not to enter what it calls a choked intersection, whether or not there is a set of traffic lights.

This means not trying to cross the intersection if it means you will end up blocking other movements.

You must also not stop your car with any portion of it obstructing access to and from a driveway, and the same goes for obstructing access by vehicles or pedestrians to a path.

At some signalised intersections traffic gets a green light when pedestrians also have a green pedestrian signal - this is known as a 'parallel walks' crossing. You might see a flashing yellow caution light to remind turning drivers that pedestrians have right of way. Don't accelerate off as you get the green, instead turn with caution, and don't creep forward as you wait to rush pedestrians off the crossing.

Lastly, go easy on the car horn. Under the Road Traffic Code, the horn is allowed to be used to "warn other road users or animals of the approach or position of the vehicle" or as part of an anti-theft device - that's it. Leaning on the horn to express your frustration of someone else's driving is not covered, and its misuse carries a fine of $50.

Macaulay says that reducing discourteous behaviours on the roads can help quell overall frustration, which improves the safety of everyone.

"There is evidence that suggests that both the victim and a perpetrator in a road rage situation are at a much higher risk of a crash, particularly if the road environment is quite complex," she says.

"We really want drivers not only to be conscious of their own driving practices, but also how these can impact other road users and put safety at risk."

We're working for safer roads

As part of RAC's commitment to reducing deaths and serious injuries on our roads, we want all national highways upgraded to a higher safety rating and all new roads to be built to at least a 4-star standard.

Find out more

Image credit: Glenn Weaver