Driverless cars could cut road delays, finds DfT study

Road construction sign telling motorists to expect delays
  • Government study shows that driverless cars could significantly cut delays once they make up a certain proportion of vehicles on the roads
  • Initial impact may be smaller, especially on faster roads, as early models take a more cautious approach

A new study by the UK’s Department for Transport (DfT) has found that driverless cars could significantly reduce delays on the nation’s roads

As the proportion of automated vehicles increases above a specific level, road delays and traffic flow were all shown to improve in virtual modelling carried out as part of the project. 

This exciting and extensive study shows that driverless cars could vastly improve the flow of traffic in our towns and cities, offering huge benefits to motorists including reduced delays and more reliable journey times.
— UK Transport Minister John Hayes

During the study, the project team used computers to create virtual models of different areas of the UK road network, comprising both urban roads and a 20 kilometre-long section of motorway.

The DfT said that the findings demonstrate that driverless cars offer the possibility of major benefits when they start to outnumber older, more traditional vehicles on the roads.



“This exciting and extensive study shows that driverless cars could vastly improve the flow of traffic in our towns and cities, offering huge benefits to motorists including reduced delays and more reliable journey times,” said Transport Minister John Hayes.

“Driverless cars are just one example of cutting edge technology which could transform the way in which we travel in the future, particularly in providing new opportunities for those with reduced mobility.”

The study found that on major roads, the benefits remain relatively small when traditional vehicles outnumber autonomous vehicles.

However, as the proportion of driverless cars increases, researchers found that journey times during peak traffic periods reduced by more than 11% and delays were cut by more than 40%.

On more urban roads, the benefits in peak traffic periods were seen even with low levels of driverless vehicles on the roads – with a 12% improvement in delays and a 21% improvement noted in journey time reliability.

Researchers examined different scenarios for the study, including the level of automation, the proportion of vehicles equipped with autonomous technologies and different automated driving styles.

The department said that the study was an “important first step” in understanding some of the effects of driverless technologies, and would pave the way for further testing and research to help ensure that the transition to driverless or automated vehicles would be a safe one.


DriverlessGuru commentary

The DfT’s study is a significant one – providing some rare insight into what the arrival of driverless cars could really mean for the UK’s motorists.

For many consumers, the idea of self-driving cars may still seem like a pipe dream. So research like this will help to raise awareness of some of the potential benefits offered by the introduction of driverless technologies.

The DfT isn’t suggesting this will happen immediately. And it’s honest about the fact that overcautious vehicles could actually hinder road performance, before things improve.

But as more research takes place and consumers begin to understand the very real changes that driverless technologies might bring, the prospect of fewer road delays and faster-flowing traffic is likely to seem like a very appealing one.