Michael Perel & Santokh Singh
SAE Govt/Industry meeting, 2003


SLIDE 1:
Forward Lighting: Problems, Research, Countermeasures

- Michael Perel
- Santokh Singh
NHTSA


SLIDE 2:
OUTLINE
- glare complaints and problems
- differences between HID and halogen headlamps
- factors affecting discomfort and disability glare
- hypotheses about glare complaints
- preliminary research findings
- future research directions



SLIDE :3
FORWARD LIGHTING GLARE CONCERNS
Over 4600 responses to request for comments on glare

public wanted reduced glare from
- auxilliary lamps
  * fog lamps
  * driving lamps
  * auxilliary low beam lamps
- high-mounted headlamps
- high intensity discharge (HID) lamps


SLIDE 4:
GLARE CONSEQUENCES IDENTIFIED BY PUBLIC
- causes annoyances and road rage
- reduces vision
- increases difficulty of using mirrors
- distracts drivers; causes yes to look away from road
- causes drivers to stop driving at night
- hurts the eyes
- causes fear of being in a crash


SLIDE 5:
NATIONAL SURVEY
[bar chart]
glare has been:
- CAUSE OF NEAR CRASH/NEAR-MISS
- DISTURBING
- NOTICEABLE BUT ACCEPTABLE
- BARELY NOTICEABLE
- NOT NOTICEABLE

by percentage frequency, 
categories: oncoming / vehicle behind / daytime
[no absolute values provided]


SLIDE 6:
ONCOMING GLARE RATED 'DISTRUBING' BY EACH AGE GROUP [bar chart]


SLIDE 7:
KEY RESEARCH QUESTIONS
- Why are drivers complaining about headlamp glare?
- what rulemaking options might reduce glare problems?
  * new photometric specifications
  * reduced mounting height
  * improved aim (static & dynamic)
  * others (e.g. washing systems, lamp color)


SLIDE 8:
HID vs Halogen
COLOR: bblue/white vs. yellow
VERTICAL INTENSITY GRADIENT: sharp vs. gradual
HORIZONTAL INTENSITY: widespread vs. limite spread 


SLIDE 9:
OBSERVATIONS ABOUT LAMP INTENSITY DISTRIBUTIONS
- maximum intensities of HID and halogen overlap
- variability in photometrics within and between lamp types
- median values show higher intensities for HID below horizontal and away from straight ahead direction
- questions remain about differences in illuminance at oncoming drivers eyes when lamps are at different heights, misaimed, on curves, and on hills

SLIDE 10:
[photos]
LENS OPTICS: 2003 Mercedes Benz E/C class
PROJECTOR OPTICS: 2002 Audi A6
COMPLEX REFLECTOR OPTICS: 2003 Acura RL


SLIDE 11:
LAMP DESIGN DIFFERENCES HID v. Halogen
[chart]

- lamp size (luminous area)
- aiming methods


SLIDE 12:
TWO TYPES OF GLARE
DISCOMFORT: 
- subjective, measured w/De Boer scale
- Influenced by: illuminance from glare source, task difficulty, ambient brightness, angle from line of sight
- may affect performance through distraction and eye strain

DISABILITY:
- direct effect on visibility distance
- increases with glare intensity, driver age, and smaller angle from line of sight


SLIDE 13:
HYPOTHESES
- HID Blue color: novely attracts atention
_ HID blue color: eyes more sensitive
- Wider beam pattern: drivers exposed to glare longer during meeting scenarios
- sharper intensity gradients: more sensitive to misaim, flickering
- smaller lamps: brigher luminance


SLIDE 14:
NHTSA GLARE RESEARCH
(at U of Iowa, completion SUmmer 2003)

1. Obtain photometric and spectral distributions of a sample of HID and halogen low beams

2. Use computer model to compare glare and visibility for HID and halogen beam patterns in different meeting scenarios

3. Conduct on-road eye-fixation study to find out if drivers take longer and more frequent looks at blue headlights


SLIDE 15:
PRELIMINARY RESULTS OF EYE FIXATION STUDY, HID vs Halogen [chart]
95% confidence interval for mean total fixation time (8)

 
SLIDE 16: 
NHTSA RESEARCH (at Renssalear's Lighting Research Center, Completion 6/2003)

Measure effects of spectral distribution, lamp size, and illuminance on glare and seeing distancel

ILLUMINANCE: 0.2, 1, 5 lx (500, 2500, 12500 cd)
SPECTRUM: halogen, blue-filtered halogen, HID
SIZE/LUMINANCE:	9cm(2)/1400000 cd/m(2), 
26 cm(2)/480000 cd/m(2), 77 cm(2)/ 160000 cd/m(2)


SLIDE 17:
PRELIMINARY FINDINGS

ILLUMINANCE
 - disability glare - SIGNIFICANT
 - discomfort glare - SIGNIFICANT
SPECTRUM
 - disability glare - not significant
 - discomfort glare - HID SIGNIFICANT
SIZE
 - disability glare - not significant
 - discomfort glare - not significant but trend


SLIDE 18:
PRELIMINARY CONCLUSIONS: 
Intensity, Spectrum, Lamp Size

- Current FMVSS method to photometer lamp intensity seems sufficient to predict disability glare for foveal and peripheral vision

- for discomfort glare
  * illuminance has greatest effect (implications for beam intensity and aiming)
  * spectrum is much smaller effect (HID more disconcerting
  * size much less so

SLIDE 19*: 
NHTSA RESEARCH (at Renssalear's Lighting Research Center, Completion 6/2003)
EVALUATE FEASIBILITY OF A GLARE LIMITING ADAPTIVE HEADLIGHT SYSTEM WHICH REDUCES INTENSITY AS A FUNCTION OF AMBIENT LIGHTING

Objectives:
- investigate how low headlamp intensity could be reduced on lighted roads while maintaining drivers' visual performance

- determine improvement in discomfort and disability glare


SLIDE 20:
FUTURE GLARE RESEARCH
- use photo-logging technique to study real world glare exposure and effects on driving behaviors (2003-4)
 

SLIDE 21:
FUTURE RESEARCH 92003-4)
- Determine effect of duration & intensity of HID glare exposure on driver re-adaptation time

- Quantify the level of misaim of different headlamp designs; assess effect of lens dirt

- Further exploration of Adaptive Forward Lighting to determine whether it can increase visibility and reduce glare

- Evaluate safety implications of other new lighting technologies, eg LED headlights