Driverless cars may limit environment benefits: study

 Driverless vehicles could intensify car use - reducing or even eliminating promised energy savings and environmental benefits, a new study suggests.

Development of autonomous driving systems has accelerated rapidly, and energy efficiency due to improved traffic flow has been touted as one of the technology's key advantages.

However, according to new research from the University of Leeds, the University of Washington and Oak Ridge National Laboratory in US, the actual impact may be complicated by how the technology changes our relationship with our cars.

While vehicle automation undoubtedly offers some efficiency benefits, if people can work, relax and even hold meetings in their cars, they may drive more.

That has the potential to erode the energy and environmental benefits of self-driving cars, researchers said.

"There is a lot of hype around self-driving cars, much of it somewhat utopian in nature. But there are likely to be positives and negatives," said co-author Don MacKenzie, an assistant professor at University of Washington

The study analyses self-driving technology combined with data on car and truck use, driver licenses and vehicle running costs to model the impact on energy demand of various levels of automation on US roads by 2050.

The study predicts that the very attractiveness of self-driving technology could outweigh the efficiency gains.

It estimates a 5 to 60 per cent increase in car energy consumption due to people choosing to use highly automated cars in situations where they would have previously taken alternative transport (eg trains or planes).

"Car owners might choose to travel by train to relatively distant business meetings because the train allows them to work and relax," said lead author Zia Wadud, associate professor at University of Leeds.

"The need to drive is part of the cost of choosing the car, just as standing on a cold platform is part of the cost of the train," he said.

"If you can relax in your car as it safely drives itself to a meeting in another city, that changes the whole equation," Wadud said.

People who currently find it difficult to drive, like the elderly or people with disabilities, will have higher access to road transport with the advent of the new systems, resulting in about 2 to 10 per cent increase in road energy use for personal travel, researchers said.

Possible higher speed limits because of the improved safety of autonomous cars (7 to 22 per cent) and demand for heavy extra equipment in driverless cars such as TV screens and computers (0 to 11 per cent) might also tend to reduce efficiency savings.

The study was published in the journal Transportation Research Part A.