Impacts of connected and autonomous vehicles on traffic flow

Driverless cars could significantly reduce delays if they become the lead mode of transport, according to this study by the DfT.The study used computer software to create virtual models of different parts of the UK road network including urban roads and a 20km motorway section.

It examined different scenarios including the level of automation, the proportion of vehicles equipped with the technology and different automated driving styles.

The results show that delays and traffic flow will improve as the proportion of automated vehicles increases.

When comparing existing peak traffic data on major roads with a situation where 100% of vehicles were autonomous, journey times reduced by as much as 11%, with delays cut by more than 40%.

When 75% and 50% of vehicles were ‘driverless’, journey times reduced by 2.2% and 1.1% respectively.

However, where traditional vehicles outnumber automated vehicles (25%), benefits were shown to be relatively small; while the average journey time fell by 0.2%, average delays rose by 0.9%.

The DfT says the study is an important first step towards understanding the full range of complex effects of this technology, and paves the way for further trials and research to help ensure the transition to driverless or automated vehicles is safe and beneficial for all.