Changes coming to federal 5-star safety ratings program

March 30, 2016

The federal government's New Car Assessment Program (NCAP) is poised to get a makeover under a sweeping proposal that would add a new oblique frontal crash test, new dummies, and new ratings for crash avoidance and pedestrian protection. The Institute urges regulators to focus on the quick wins, while postponing other changes that need more study and longer time to implement.

The timetable for updating the 38-year-old program is aggressive. By year's end, the National Highway Traffic Safety Administration (NHTSA) intends to finalize the changes and begin ratings under the new system in 2018 for model-year 2019 vehicles. The agency asked for public comments on its proposal, which it issued in December 2015.

"The Institute strongly supports efforts to provide consumers with enhanced vehicle safety information that rewards auto manufacturers who lead the industry in safety advancements and encourages others to improve," Joe Nolan, IIHS senior vice president for vehicle research, said in the Institute's Feb. 16 comment to the agency.

NHTSA crash-tests new vehicles and rates them on how well they protect people in full-frontal, side and rollover crashes. Vehicles get a rating of 1 to 5 stars. The IIHS vehicle ratings program, which began in 1995, complements NCAP and has grown to include offset front, side, rollover and rear tests, automatic braking tests and, now, headlights.

The broad changes NHTSA is proposing should help raise the bar on safety. In particular, crash avoidance technology evaluations and enhanced protection for pedestrians struck by passenger vehicles are important improvements. Some of the proposed changes, however, aren't detailed enough to allow for a thorough review, while others aren't fully supported by scientific data.

The revamped 5-star safety ratings would include a crash avoidance rating based on whether or not a vehicle has one or more of nine features and how they perform in NCAP tests. These include: forward collision warning and automatic emergency braking; lane departure warning; blind spot detection; frontal pedestrian autobrake; rear pedestrian autobrake; high-performing low-beam headlights; high-beam assist; and amber rear-turn-signal lamps.

IIHS notes that some crash avoidance features have more support than others. In particular, lane departure warning hasn't been found to reduce insurer-reported crashes and is often disabled by drivers (see "Most Honda owners turn off lane departure warning," Jan. 28, 2016). NCAP already awards credit for lane departure warning, but NHTSA aims to modify the existing performance criteria. Even with the proposed test changes, IIHS believes the agency should shelve lane departure warning credit until the systems' real-world benefits are established. That would give manufacturers the freedom to design new systems that are effective and acceptable to drivers.

A new pedestrian protection rating would be based on the performance of autobrake systems capable of detecting and braking for pedestrians in front of or behind a vehicle and impact testing of the front of a vehicle to evaluate injury risk when impacts occur. IIHS supports the impact tests. Although there is a lack of evidence on rear autobrake's effectiveness, the technology has the potential to prevent more crashes than rear cameras alone.

IIHS urges NHTSA to take into account how IIHS and Euro NCAP are evaluating the performance of crash avoidance technologies and diverge from these procedures "only when there is empirical evidence that doing so will bring measurable benefits."

NHTSA plans to add a new crash test to measure how well vehicles protect people in an angled frontal crash. The test would use the THOR 50th percentile male dummy in the driver seat and the modified Hybrid III 5th percentile female dummy in the right rear seat. The vehicle would be stationary and struck by a moving barrier at a 15-degree angle, with a 35 percent overlap and 56 mph impact speed. The test would simulate two midsize vehicles colliding with a 50 percent overlap and an impact speed of 35 mph, the same severity as NCAP's full-width frontal rigid barrier test.

Vehicle mass will be a dominant performance factor in the moving barrier test, giving bigger, heavier vehicles, such as large cars, the edge over smaller, lighter ones, such as minicars. There might not be large differences among ratings within a vehicle class, which will make it difficult to determine, for example, which small cars are safer than others. Since consumers tend to focus on a certain group when shopping for a vehicle, NHTSA should ensure that its new test highlights meaningful differences in the performance of similar-size vehicles.

In addition, IIHS strongly recommends that NHTSA delay use of a proposed head injury metric known as the Brain Rotational Injury Criterion, or BrIC. Numerous studies indicate that BrIC, as currently calculated, significantly overestimates injury risk and doesn't align with real-world data. IIHS also recommends NHTSA penalize vehicles with excessive occupant compartment intrusion in the test. Minimizing intrusion is key to protecting occupants from serious injuries in crashes.

IIHS agrees that crash tests should use the most biofidelic dummies available but notes that NHTSA hasn't supplied any comparative data to show that THOR, the modified Hybrid III 5th percentile female and the WorldSID 50th percentile male it proposes to use would provide more benefits and drive better vehicle designs than the dummies currently used. What's more, these dummies haven't been finalized in federal standards and aren't readily available.

The upgraded NCAP would feature an overall safety rating combining the results for crashworthiness, crash avoidance and pedestrian protection. IIHS recommends that NHTSA continue to publish ratings indicating how vehicles perform in individual tests.

NCAP would give half-credit for optional crash avoidance systems. Nolan points out that the practice could mislead consumers since standard systems would always score better, even if they don't perform as well as optional systems. IIHS urges NHTSA to evaluate vehicles both with and without the crash avoidance technologies and publish dual ratings in the case of optional features. IIHS incorporated this strategy when a mix of optional and standard side airbags was in the fleet to provide clear indication of the airbags' benefit to consumers.

NHTSA 5-star rating logo

Planned additions to NHTSA's 5-star safety ratings program include:

  • Crash avoidance rating, including headlights
  • Pedestrian protection rating
  • Frontal oblique crash test
  • New dummies and injury criteria
  • Half-star rating increments
  • Half-credit for optional crash avoidance technologies
THOR 50th percentile male dummy
The THOR 50th percentile male dummy would replace the Hybrid III dummy in NCAP tests under NHTSA's proposal.

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