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Tessmer et al - 2003 SAE Govt/Industry meeting
Daytime Running Lamps (DRLs)


SLIDE 1:
AN ASSESSMENT OF THE CRASH REDUCTION EFFECTS OF PASSENGER VEHICLE DAYTIME RUNNING LAMPS (DRLs)

 - Anders Longthorne
 - Ana Maria Eigen
 - Joseph Tessmer


SLIDE 2:
1st NHTSA STUDY ON DRIs
 - published June 2000
 - restricted to passenger cars
 - used make model, and model year data to identify vehicle with and without DRLs
 - two different comparison groups - older similar model cars & Ford vehicles
 - simple odds and odds ratio


SLIDE 3:
WHAT ARE DRLs?
DRL CONFIGURATIONS
 - upper beam headlamps at reduced power
 - lowe-beam headlamps at full or reduced power
 - turn signals
 - dedicated lamp - (some GM light trucks)


SLIDE 4:
PURPOSE OF DAYTIME RUNNING LAMPS
Increase the visual contrast of DRL equipped vehicles during daylight, thereby:
 - reducing multiple vehicle opposite direction/angle crashes
 - reducing single vehicle crashes with non-motorists


SLIDES 5-6:
SUMMARY OF FINDINGS
[tables]


SLIDE 7:
PROBLEMS WITH USA DRL ANALYSIS
- Law permits the use of DRLs but does not require
  * some vehicles are equipped with DRLs
  * other vehicles do not have DRLs
- DRLs are being phased in over time
- But problems can be advantages as well


SLIDE 8:
DATA SETS USED
- Fatality Analysis Reporting System (FARS) 1995 to 2001

- National Automotive Sampling System (NASS) 
  General Estimates System (GES)
  * 1995 to 2001
  * property damage and injury crashes only
  * no crashes involving a fatality


SLIDE 9:
PASSENGER VEHICLE TYPES
 - passenger cars
 - pickups/light trucks
 - sport utility vehicles (SUVs)
 - vans

SLIDE 10:
VEHICLE DRL STATUS
- vehicles equipped with DRLs
- vehicles without DRLs
  * as determined by analysis of the VIN
  * vehicles with DRLs as an option were eliminated from the analysis


SLIDE 11:
CRASHES
- TARGET CRASHES [DRLs should have an effect]
 Two vhicle
  * head on
  * angle
  * sideswipe opposite direction

- COMPARISON CRASHES [DRLs have no effect]
 Single vehicle crashes


SLIDE 12:
PERSONS

- TARGET PERSONS [DRLs should have an effect]
  * non-motorists involved in single vehicle fatal crashes (pedestrians and cyclists)

- COMPARISON PERSONS [DRLs have no effect]
  * occupants of single vehicle fatal crashes


SLIDE 13:
TIME OF DAY
 - DAYTIME: DRLs should be effective
 _ NIGHT: DRLs should not have any effect


SLIDE 14:
WHAT IS IGNORED?
 - effect on motorcycles/snowmobiles
 - drivers do not turn on head lamps at night
 - a 2-vehicle crash maybe avoided, which becomes a single-vehicle crash
 - possible increases in comparison crashes
 - climate/seasonal differences
 - interactions
 - burned out bulbs/very bright bulbs


SLIDE 15:
EFFECTIVENESS IS THE MEASURE OF CRASH REDUCTION DUE TO A PROGRAM
 - effectiveness
 - the percent change in the number crashes that can be affected by the program, 
	compared to
 - the percent change in the number of crashes that are not affected by the program.

SLIDE 16:
GENERAL EFFECTIVENESS

SLIDE 17:
GENERAL EFFECTIVENESS (degenerate case)
- let Omega = TD/(CD = TN = CN)
- the simple odds - where:

TD = number of vehicles/persons in Targeted crashes during Daylight
CD = number of vehicles/persons in Comparison crashes during Daylight
TN = number of vehicles/persons in Targeted crashes at Night
CN = number of vehicles/persons in Comparison crashes at Night


SLIDE 18:
GENERAL EFECTIVENESS
[formula]

SLIDE 19:
ADVANTAGES OF GENERAL EFFECTIVENESS APPROACH
- calculates the statistical significance, p.
- works for censuses and surveys.
- can adjust for a variety of factors
- equivalent to the simple odds
- generalizations also exit<sic> for the odds ratio



SLIDE 20:
WHY USE THE SIMPLE ODDS?
the simple odds, omega, is more stable, smaller standard error than the odds ratio

SLIDE 21:
HOW EFFECTIVE ARE DRLs?
PRELIMINARY RESULTS
* two vehicle opposite direction/angle fatal daytime crashes 	 5% (p=0.0680)

* two vehicle opposite direction/angle non-fata daytime crashes	5% (p=0.0751)

* single vehicle fatal non-motorist daytime crashes	12% (p=0.0023)


SLIDE 22:
JUNE 2000 RESULTS
- two vehicle opposite direction/angle fatal daytime crashes 		5% to -28% (nothing significant)
- two vehicle non-fatal daytime crashes [from the State Data System]
	22% to -16%
- Single vehicle fatal nnon-motorist daytime crashes
	24% to 35% (nothing significant)


SLIDE 23:
THE EFFECTIVENESS ESTIMATES DEPENDENT ON VEHICLE TYPE
Passenger cars, SUVs, Vans, and pickups

When adjusting for vehicle type the effectiveness estimates are:
 - two vehicle fatal daytime OD/A* crashes 5% (p=0.0799)
 - two vehicle non-fatal daytime OD/A* crashes 5% (p=0.1333)
 - single vehicle fatal non-motorist daytime crashes 13% (p=0.0016)

  * OD/A opposite direction/angle

SLIDE 24:
PRELIMINARY CONCLUSIONS
 - daytime running lamps (DRLs) seem to reduce target crashes by 5-12%.

 - the 5% reductions are not statistically significant, but 12% reduction is.

 - the effectiveness of DRLs is not dependent on the type of passenger vehicle