1. IIHS headlight ratings
American Traffic Safety Services Association
November 2, 2016
Matthew Brumbelow
Sr. Research Engineer

2. Motivation for headlight evaluation program
16,768 annual crash deaths in dark/dawn/dusk light conditions (2013 FARS)
HLDI analyses point to benefits for curve-adaptive headlights (2012 HLDI analyses of Mazda, Acura, Mercedes, Volvo claims)
Human factors experiments have established link between improved lighting and detection performance
FMVSS 108 produces wide range of on-road visibility
Large variation in allowable intensity
Performance is not measured when installed, so factors like lamp height and spread are not captured
Aim is not regulated and varies widely, often by manufacturer

3. Dynamic headlight test setup
Vehicle approaches:
150 m radius left and right curves at 40 mph
250 m radius left and right curves at 50 mph
Straightaway at 40 mph
Record illuminance readings for:
Visibility – edges of road at 25 cm above ground
Glare – center of oncoming lane (110 cm)
Light sensor array
150 m radius
straightaway
direction of travel
250 m radius

4. Sample data: straightaway
3 different approaches for same vehicle
Visibility metric: distance at which 5 lux illumination is reached

5. Other protocol details
Headlights are tested with factory aim (no re-aiming)
Average 3 valid runs from each test condition
Testing every available headlight system on rated models

6. Initial midsize car results: low beam 4 curve average

7. Initial midsize car results: low beam straightaway

8. Differences in headlight illumination
Deer is 270 feet from front of car; approximate reach of Accord’s 5 lux
Honda Accord
Mercedes C300

9. Translating test results to ratings
Rating based on:
Straightaway and curve visibility (weighting roughly 60/40)
Low and high beams (weighting roughly 75/25)
Acceptable glare: downgrade for each individual low beam scenario with excessive glare
Bonus given for high beam assist
2016 IIHS study: only 18% of isolated vehicles used high beams
Results of all tests are combined into an overall demerit score with rating boundaries applied

10. Midsize car results

11. First ratings release: March 30
Toyota Prius v
Website example of results presentation:

12. Subsequent releases
Small SUVs: July 12
Pickups: October 25

13. Moving forward
Beginning with the 2017 model year, Good or Acceptable headlight ratings are required for the highest IIHS award—Top Safety Pick+
Manufacturers have been improving performance by offering new headlight systems and improving their factory aiming procedures and tolerance
As with all our evaluations, when there is sufficient crash data we will study the real-world effect of ratings differences
The ratings have been very popular with consumers—highest web traffic days have come on headlight release dates