The forward blind zones of six top-selling passenger vehicles have grown substantially over the past 25 years, as pedestrian and bicyclist fatalities have soared, according to a comparison technique developed by the Insurance Institute for Highway Safety (IIHS).

A study led earlier this year by researchers from the U.S. Department of Transportation’s Volpe Center was the first to use the new IIHS method for measuring a driver’s direct area of vision around a vehicle.

IIHS says the technique promises to enable much broader studies of the role that vehicle design plays in driver visibility and crash risk.

Model years 1997-2023 Chevrolet Suburban, Ford F-150, Honda Accord, Honda CR-V, Jeep Grand Cherokee, and Toyota Camry vehicles were examined in the study.

Throughout the multiple redesign cycles for those model years, forward visibility within a 10-meter radius decreased 58% for the three SUVs, according to IIHS. The F-150’s close-proximity visibility declined by 17%, but even the earliest model had “extremely large” blind zones. In contrast, early models of the Accord and Camry had relatively good visibility, which fell by less than 8% in later generations.

“The across-the-board decrease in visibility for this small group of models is concerning. We need to investigate whether this is a broader trend that may have contributed to the recent spike in pedestrian and bicyclist fatalities,” said IIHS President David Harkey, in a press release. “This study also illustrates that the new method developed by IIHS gives researchers a straightforward, repeatable way to assess driver visibility.”

In the past, researchers who wanted to compare the blind zones of different models needed to acquire engineering drawings or position each vehicle in an open area specially marked with grid lines or traffic cones. The cumbersome methods led to no attempt at large-scale comparisons. An alternative technique using lasers is efficient, but doesn’t capture blind zones created by the side mirrors and widening base of the A-pillars.

The new IIHS method uses computational software and a portable camera rig that can be positioned in the driver seat at various heights, representing different-sized drivers, and isn’t dependent on the vehicle location. The camera rotates to create a 360-degree image of the field of vision around the vehicle, and the software converts that image into a blind zone map that depicts an aerial view of the vehicle and the nearest points on the ground that the driver can see. It also provides a numerical value for the percentage of the area around the vehicle that is visible.

An April IIHS study introducing the technique showed that the blind zone maps it produces are nearly identical to traditional methods created with a physical grid.

“By allowing engineers and researchers to collect data at car dealerships and other easily accessible locations, it promises to facilitate a raft of new research into driver visibility,” the release states. “Researchers from IIHS and the affiliated Highway Loss Data Institute are already working on comparing blind zone maps for around 150 vehicle models, exploring the effects of different-sized blind zones on pedestrian crashes, and examining the relationship between blind zone sizes and insurance losses, for example.”

The Volpe Center’s examination of the six study vehicle models and design changes required blind zone maps of 17 vehicles to represent each major redesign.

“That 25-year period is of interest because pedestrian and bicyclist fatalities on U.S. roads have soared 37% and 42%, respectively, over that time span,” the release states. “There is not one clear cause for the increase, but research has linked it to factors like population growth in areas with poor pedestrian infrastructure, speed increases, and changes in vehicle size and shape. Recent IIHS studies, for example, have shown that the height of a vehicle’s front end amplifies the effect of higher crash speeds on fatality risk and that vehicles with blunt front ends are more deadly than those with sloping profiles. However, little is known about what role changes in driver visibility have played in the increase.”

The Volpe Center study focused on forward visibility within a 10-meter radius of the vehicle because that is the average driver stopping distance at 10 mph, a low speed at which blind zones are a common factor in crashes and calculated the percentage of the 180-degree area that was unobscured by obstacles like the vehicle hood, the rearview mirror and the A-pillars.

The most dramatic reduction came for the Honda CR-V, as the vehicle’s hood, mirrors, and A-pillars obstructed a greater portion of the driver’s view over time. Drivers of the 1997 model were able to see 68% of the area 10 meters in front of the vehicle, while drivers of the 2022 model can see only 28%. Similarly, drivers of the model year 2000 Suburban (the earliest model of that vehicle studied) could see 56% of the area 10 meters in front of them, while drivers of the 2023 model could see only 28%.

The researchers found that for both of the vehicles, the biggest changes in the blind zone were due to a higher hood that blocks more of the frontal plane and larger side mirrors that obscure the views at their front corners.

The forward visibility provided by the F-150 also declined, starting from a very low base. Drivers of the 1997 model could see 43% of the forward area within a 10-meter radius, and that dropped to 36% by model year 2015.

The visibility reductions for the two cars were less severe. The Accord had the smallest decrease, which permitted the driver to see 65% of the area 10 meters in front of the vehicle in 2003 and 60% in 2023. For the Camry, visibility decreased from 61% in 2007 to 57% in 2023. Both of these decreases fell within the margin of error.

Becky Mueller, IIHS senior research engineer, who led the development of the new mapping technique and is a co-author of the Volpe Center study, said the results are notable because it’s already known that SUVs in the U.S. fleet grew substantially over the same time period.

“If further research confirms that these changes reflect a general change, that would suggest that declining visibility in SUVs has compounded the effects of taller, blunt-nosed vehicles that IIHS has already documented,” she said in the release.

In December, IIHS reported that the effect of crash speed on pedestrian injury risk is magnified for vehicles with taller front ends, beginning at lower speeds.

“The faster a vehicle is moving when it strikes a pedestrian, the more likely it is to inflict serious injuries,” states an IIHS press release. “Exactly how much more likely depends in part on the height of the vehicle, with taller vehicles compounding the risk from higher crash speeds.”

IIHS researchers analyzed pedestrian crashes to develop injury risk curves showing how speed affects crash outcomes. Compared with risk curves developed using crash data from Europe, where tall passenger vehicles are less common, risk curves for the U.S. show pedestrians begin to suffer more serious injuries at lower speeds, the result of “our fondness for tall SUVs and pickups in the U.S.,” according to IIHS President David Harkey.

“A small increase in crash speed can really ramp up the danger to a pedestrian,” Harkey said in the release.

And height “has intensified that effect,” he added.

Images

Featured image provided by IIHS

An example of a 360-degree blind zone map created using the new IIHS measurement technique. The blue overlay represents the areas that are blocked from the driver’s direct vision by vehicle components. (Provided by IIHS)