If you live in an urban area, you might have seen signs by the roadside calling for “No Idling Engines” and warning of noxious exhaust in the vicinity of pedestrians. In recent years, these signs have appeared in neighborhoods and around schools across England. Local governments have implemented regulations whereby idling drivers can be fined, usually £20, for failing to turn off their engines when waiting for passengers or stopping for any other reason. But how problematic is idling? Does regulating it produce any benefits to drivers or community members? If it does, what regulatory methods work best?

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Engine idling is unproductive for drivers and damaging for community members.

Idling refers to running a car's engine when the car is not moving, and it has come under fire in recent years because it contributes heavily to climate change. Road transport causes around 21% of greenhouse gas emissions in the UK, and engine idling produces a significant fraction of these emissions. For every minute its engine is left idling, a car produces enough emissions to fill 150 balloons. For every hour its engine is left idling, it consumes nearly five litres of fuel and emits nearly 10 kilograms of greenhouse gases. Trucks and other heavy vehicles idle for an average of 25% of all operational time per day, and this number is as high as 40% in some sectors. This excess fuel not only wastes money but also fails to increase the vehicle’s lifespan, as drivers often assume it will.

On top of this, the pollution in vehicle exhaust can aggravate asthma and allergies and lead to cardiovascular and respiratory disease, including cancer. The Royal College of Physicians estimate 40,000 deaths a year in the UK are linked to air pollution, with engine idling contributing to this. Children are especially vulnerable to these health problems because their bodies are more easily damaged, and they often face greater exposure to vehicle exhaust. Over 2,000 British schools and nurseries are located in areas with illegal levels of pollution, and recent research shows 60% of parents in the UK are worried about the effects of air pollution on their children’s health. A study of more than 2,000 children in London revealed that air pollution could reduce lung capacities by up to 5%.

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However, idling can be effectively discouraged, especially using behavioral techniques.

Some cities have created “no-idling zones” in areas where idling is common, including around schools and in car parks. These zones are patrolled by traffic enforcement officers, who can ask drivers to turn off their engines and issue fines if they fail to comply. Yet, this is not the only method for reducing idling, and other methods may prove more cost-effective and engaging in the long run.

A 2018 study used behavioral models to test whether appeals to self-interest can encourage drivers to turn off their engines at long wait stops. In the study, drivers were shown one of three self-interest appeals, to finances, health, and kin, while waiting at a level-crossing site in the U.K.. Results showed that the presence of self-interest appeals made drivers nearly twice as likely to turn off their engines compared to drivers in the control condition.

Another study, from 2019, placed monitors near level train crossings at two locations in Canterbury where air and noise pollution were normally high. Three different messages were rotated over the course of five weeks, and researchers recorded whether or not vehicle engines were left idle, along with other relevant circumstances, including the weather and the number of people in each car. They found that the intervention messages led people to switch off their engines 16-38% more often. At these rates, installing permanent signage would be equivalent to taking 123 cars off the road each year.

Behavioral research on idling has revealed the promise of nudges and social responsibility messages, but signage is targeted largely towards passenger vehicles. For HGV drivers, who face substantial on-the-job stress and pay greater attention to company policies than external encouragement, signage alone may not be enough to address inefficiencies and cut costs. More impactful action on idling will come at the company level, including by adopting technology that encourages drivers to idle less. Signol’s expertise is well suited to fill this need. By encouraging HGV drivers to reduce idling, Signol’s behavioral messaging can improve public health and save lives. Find out what we can do for you.

Title photo by Robert V. Ruggiero on Unsplash