Adaptive cruise control (ACC) and more sophisticated partial automation are as much as 75% less likely to be functioning on freeway curves, limiting their potential safety benefits, according to new research from the Insurance Institute for Highway Safety. 

While many studies suggest that ADAS tech helps prevent crashes, motorists have to embrace the technology for it to work. A key finding in this latest study is that ACC and ACC with lane centering are often disabled on curvy roadways —either because they deactivate automatically or because drivers choose to turn these features off. 

The findings beg the question: Do drivers trust sophisticated automation to handle curves as well as human skill would? 

Researchers collected data from two 2016 Land Rover Range Rover Evoque and two 2017 Volvo S90 vehicles driven by 39 drivers over four weeks. The Evoques were equipped with ACC, and the S90s were equipped with both ACC and Volvo’s Pilot Assist partial automation system — which combines ACC and lane centering.

The findings showed that ACC or Pilot Assist were less likely to be active as curves became sharper. 

Drivers of the Evoque vehicles were 72% less likely to use ACC on the sharpest category of curves — those with a radius smaller than 2,292 feet — than they were to use those features on straight road segments. Moreover, drivers of the S90 were 75% less likely to use Pilot Assist and 66% less likely to use ACC on the sharpest curves.

Whether or not the driver switched off the system or it deactivated automatically remained undetermined. 

The study indicates that automation is being underused which undermines safety. For example, Pilot Assist was frequently inactive on the sharpest curves, yet the kinds of crashes lane centering can help prevent are more likely to occur on curves than on straightaways.