Image courtesy of IIHS

IIHS Finds Little Evidence Some Electronic Driving Aids Reduce Crashes

July 11, 20245 months ago Steve Hanley 0 Comments

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How fitting that on a day when Tesla announced that its next really, really big thing — the public unveiling of its long promised robotaxi — was not going to happen on August 8 as planned, the Insurance Institute for Highway Safety together with the Highway Loss Data Institute, issued a report saying that crash records and insurance data offer little evidence that partial automation systems are preventing collisions. “Everything we’re seeing tells us that partial automation is a convenience feature like power windows or heated seats rather than a safety technology,” IIHS President David Harkey said.

The clearest evidence so far comes from studies of BMW and Nissan vehicles that have been on the road for a number of years. HLDI studied these vehicles in 2021. Now a new study of the same vehicles from IIHS confirms that partial automation in these vehicles doesn’t confer additional safety benefits beyond those of crash avoidance features like front automatic emergency braking. More than half the new models for sale in 2023 were available with partial automation systems as an optional or standard feature, despite mounting concern over a series of high profile crashes that occurred while drivers were using the technology. Using cameras and other sensors, these systems can keep your car moving down the road in the center of the lane, navigating curves, slowing down to avoid other vehicles and then accelerating again when the way is clear.

But vehicles equipped with these systems are far from self-driving. They can’t manage many routine roadway features and traffic situations, so drivers have to pay close attention to what’s happening on the road and be ready to take over at any time. That’s a big challenge because the technology can encourage a false sense of security and induce boredom, causing drivers to tune out, the IIHS says.

IIHS — Crash Avoidance Vs Partial Automation

There’s a key difference between partial automation systems and the crash avoidance features that are usually included with them but also sold separately. Crash avoidance features like automatic emergency braking, blind spot warning, and lane departure prevention only come into play when a potential danger arises, applying the brakes to avoid rear-ending another vehicle, for example. Because they’re unobtrusive under normal circumstances, most drivers leave these features switched on all the time.

Using insurance claims data, HLDI has conducted multiple investigations into the potential safety benefits of crash avoidance features. Broadly speaking, the studies have all shown that features that warn or intervene in an emergency reduce the frequency of insurance claims and the reductions increase incrementally as one feature is stacked on another. In contrast, a partial automation system works constantly to keep the vehicle in the desired position on the road. Intended for use on highways and other limited access roads, they must be switched on whenever the driver wants to use them, which most drivers do only occasionally.

One of the components of partial automation — adaptive cruise control — keeps the vehicle traveling at a speed specified by the driver when the road ahead is clear. It slows and accelerates to maintain a set distance from vehicles ahead. It is associated with longer following distances, less tailgating, and fewer lane changes — all positive driving behaviors that can reduce risk. The other main component of partial automation, lane-centering, could potentially do a better job in preventing sideswipes and running off the road crashes than lane departure prevention, since lane centering theoretically would preempt such departures rather than intervening as they occur.

IIHS & Crash Data

So far, there’s little evidence that’s happening, studies of BMW and Nissan vehicles show. HLDI found that property damage liability claims — which are for damage to other vehicles hit by the insured driver — were 8% lower for 2017-19 Nissan Rogues equipped with forward collision warning and AEB. However, there was no additional benefit associated with ACC or Nissan’s ProPILOT Assist partial automation system, which adds lane-centering on top of ACC. Changes in claim rates under collision coverage, which is for damage to the insured driver’s own vehicle, were small for all the technologies.

Similarly, forward collision warning and AEB were associated with a 7% reduction in collision claim rates and a 13% reduction in property damage liability claim rates for 2013-17 BMW and Mini vehicles. BMWs and Minis that were also equipped with ACC showed a larger, 25% reduction in property damage claims and no greater change in collision claims. As with the Nissan vehicles, there were no additional statistically significant reductions associated with BMW’s Driving Assistant Plus partial automation system.

HLDI’s claims data, collected from insurers representing 85% of the private passenger vehicles in the US, do not show whether the partial automation system was switched on during a crash, nor do they include the type of road where the insurance claims occurred. That means any potential benefits from partial automation, which is generally designed to be used on high speed roads, would be diluted by the large volume of insurance claims for low speed fender-benders.

Jessica Cicchino, senior vice president for research at IIHS, tried to determine if such safety benefits might be hiding in the HLDI data. She compared police-reported crash rates for the same BMW and Nissan vehicles that HLDI studied in 17 U.S. states during 2013-22. Although she also had no way of knowing whether the features were switched on at the time of the crash, she was able to restrict her study to the front to rear and lane departure crashes that partial automation could potentially prevent. She looked at crashes on limited access interstates, freeways, and expressways, and then looked separately at crashes on other roads.

Like HLDI, she found substantial reductions in crash rates associated with crash avoidance features. Front to rear crash rates were 49% lower for Rogues with forward collision warning and AEB and 54% lower for Rogues with forward collision warning, AEB and ACC than for vehicles with no crash avoidance features. There was no significant effect on lane departure crash rates from lane departure prevention.

Unlike HLDI, Cicchino found larger reductions associated with partial automation. Front to rear crash rates were 62% lower for Rogues with ProPILOT Assist than for vehicles without any crash avoidance systems. Lane departure crash rates were 44% lower for Rogues with ProPILOT Assist and lane departure prevention than for unequipped vehicles.

Things Are Not Always As They Appear

When she looked into those numbers more deeply, however, she found that the apparent benefits from ProPILOT Assist were the same on high speed roads where IIHS research shows partial automation is most likely to be switched on and low speed roads where the added convenience it provides is minimal at best. Below 37 mph, in fact, ProPILOT Assist’s lane-centering feature only works if you are following another vehicle. That suggests that other characteristics of the equipped vehicles or their drivers were responsible for the reduction.

One such characteristic may be the vehicles’ headlights. Rogues of that vintage were equipped with poorly rated headlights unless the buyer opted for a premium package. Cicchino turned to the crash records again and discovered that the rate differences were greatest in the dark. From Nissan marketing materials, she ascertained that the 2018 and 2019 Rogues with ProPILOT Assist were more likely than unequipped vehicles to have acceptable rated headlights, which reduce single vehicle nighttime crashes by about 15% compared with poorly rated ones, other IIHS research has shown.

For the BMW vehicles, Cicchino examined only lane departure crashes because the vehicles with partial automation came with a more advanced front crash prevention system than those without partial automation, making it impossible to isolate the effect of the partial automation system on front to rear crashes. She found that neither lane departure prevention alone nor the same feature combined with partial automation had a significant effect on crash rates, either on limited access highways or on roads with lower speed limits.

The vehicles in these studies range from five to 11 years old, and it’s possible that newer partial automation systems are more effective from a safety perspective, IIHS says. On the other hand, the many years of data that have accumulated for these vehicles make the findings more compelling. “With no clear evidence that partial automation is preventing crashes, users and regulators alike should not confuse it for a safety feature,” Cicchino said. “At a minimum, safeguards like those IIHS promotes through its rating program are essential to reduce the risks that drivers will zone out or engage in other distracting activities while partial automation is switched on.”

What About Tesla?

Readers will immediately note that none of the data studied by IIHS included Tesla automobiles, probably because Tesla plays its cards very close to the vest and is stingy about sharing data with anyone. That means this report from IIHS does not inform us about the effectiveness of the much ballyhooed Tesla Autopilot and Full Self Driving systems. Elon Musk claims they reduce crashes significantly and perhaps they do, although IIHS seems less impressed with the performance of its systems that Tesla itself is. What the IIHS report seems to suggest is that some automated features — such as forward collision warnings and emergency forward braking — are quite successful at reducing crashes, while lane-centering and lane departure systems are less successful at reducing them.

But the subtext to all this is only hinted at in the IIHS report, and it has less to do with digital technology and more to do with the human brain. We have a bias built into our cranial coding that makes us more likely to trust computers than is wise. We assume a computer can do things it may in fact be incapable of. That leads us to let our attention wander when we should be vigilant, something even Tesla has not been able to address adequately.

We step on an elevator, press the button for the 37th floor, and have every confidence the machine will deliver us to our chosen destination every time. We give it no thought at all and in fact are shocked if it fails to faithfully complete the assigned task. We are inclined to believe that our car with all its electronic geewizardry can negotiate a highway or a city street because we want to believe it can.

My old Irish grandfather liked to say the most dangerous part of any vehicle was the nut behind the wheel. He was an irascible old codger, but he wasn’t wrong. We desperately want our cars to be able to drive themselves, and maybe some day they will, but that day is not here yet. When it will arrive is a matter of much conjecture and speculation. Tesla says it will be sometime in October. “We’ll see,” said the Zen master.