Almost 9 out of 10 drivers of vehicles equipped with lane departure warning and prevention systems now keep them switched on, according to a new study from the Insurance Institute for Highway Safety.

Seven out of 10 drivers of vehicles that give visual alerts when they exceed the speed limit also keep that feature running.

“These results hint at a growing awareness that crash avoidance systems and other technologies can improve safety,” said IIHS President David Harkey. “They also indicate that automakers’ efforts to increase usage rates have been a success.”

Lane departure warning and prevention systems could address as many as 23 percent of fatal crashes involving passenger vehicles, though they haven’t had the same dramatic effects on insurance claims and police-reported crashes as forward collision warning and automatic emergency braking (AEB).

That’s likely because front-to-rear crashes — especially minor ones — are much more common than sideswipe, head-on and run-off-road crashes that lane departure systems address, the IIHS noted. The effectiveness may also have been limited initially because many drivers found lane departure alerts annoying and switched them off. By and large, automakers have solved that problem, the new study shows.

Of the nearly 2,400 vehicles of various makes that were brought to dealerships in the Washington, D.C., metropolitan area for service, IIHS researchers found that lane departure warning and prevention systems were activated in 87 percent. In contrast, only 51 percent of vehicles in a similar study conducted eight years ago had any kind of lane maintenance system activated.

The current survey showed that front crash prevention — forward collision warning or AEB — was activated in 94 percent of the vehicles, compared with 93 percent in the earlier one. In many of today’s designs, those features can’t be disabled.

The safety features examined in the current study included both lane departure prevention, which provides minor steering adjustments to help redirect the vehicle if it nears the edge of the lane, and lane departure warning. However, only 1 percent of vehicles in the study had warning-only systems. Of the 99 percent that had lane departure prevention, 11 percent had only the warning function enabled, while 76 percent had the prevention function enabled.

At the time of the earlier study, warning-only systems were the most common type of system but the least likely to be switched on.

The new study found that systems that are activated and deactivated through the in-vehicle settings menu, rather than a button, were more likely to be switched on. Seven years ago, only one of the observed models was designed that way, while a little more than half of vehicles in the new sample were, one likely factor contributing to the increased use.

A change in the alert mode could also account for increasing acceptance.

Past research has shown that drivers find audible lane departure alerts annoying. In the earlier study, that was reflected in higher activation rates for systems that used haptic alerts such as seat or steering wheel vibrations instead.

The same preference was clear in the new study, but this time four of the six automakers covered in the study either primarily used haptic alerts or allowed the driver to select their preferred alert mode, with haptic as an option.

Activation rates for the two that continued to use visual and audible alerts were substantially lower than for other manufacturers.

“The results reflect a combination of better designs and a growing acceptance of crash avoidance systems, more generally,” said IIHS Research Scientist Aimee Cox, the lead author of the study. “The new designs make the feature a little harder to turn off and a lot less annoying for the driver.”

The study’s finding of high activation rates also bolster the results of a recent IIHS survey of drivers who had never used this anti-speeding technology, which showed that 60 percent of drivers would find speeding alerts acceptable.

The researchers found that visual speed warnings were activated in 70 percent of vehicles. In contrast, systems that gave an audible warning when the driver exceeded the speed limit were only switched on in 14 percent of the vehicles observed.

Intelligent speed assistance (ISA), use a camera capable of reading posted signs, a GPS with a speed limit database, or both to identify the speed limit on the section of road the vehicle is traveling, the IIHS explained. The European Union now requires all new vehicles to be equipped with ISA systems that at least give visual alerts with either cascading audible or haptic warnings.

Visual-only alerts can easily go unnoticed, and warnings of any kind will only work if drivers keep the feature switched on.

Differences among the ISA designs used by the six manufacturers illustrate other practices that could encourage drivers to keep the feature turned on, even with audible alerts.

Delivering vehicles with speed warnings enabled, for example, could help encourage use. Setting the audible alerts to kick in at 5 or 10 mph over the speed limit as the default might have a similar effect, as drivers who activated their audible alerts were more likely to have selected a higher threshold than those who had only visual alerts on.

The alerts could be configured to occur when the driver exceeds the speed limit by a certain percentage, so that the feature remains effective in residential areas and on other lower speed roads where there are more bicyclists and pedestrians, the IIHS suggested.

Finally, automakers could design the systems to initially warn drivers visually but escalate to audible or haptic alerts if the driver doesn’t reduce their speed. They could also configure ISA systems to switch on with each new ignition cycle, regardless of the last setting.

“The increased acceptance of lane departure prevention should translate into larger reductions in crash rates,” Harkey said. “The same thing can happen with anti-speeding alerts — which these results show are already more popular with drivers than some experts believed possible.”