What
are Daytime running lights? Daytime
running lights (DRLs) are a crash avoidance feature
new to vehicles sold in the US, but they've been
used for
years in Canada and Scandinavia to help prevent crashes
by making vehicles more conspicuous or visible to
oncoming traffic.
What
are the safety advantages of DRLs?
Daytime running lights are a low-cost method
to reduce crashes. They are especially effective in
preventing daytime head-on and front end collisions
by increasing vehicle conspicuity and making it easier
to detect approaching vehicles from farther away.
How
effective are DRLs?
Nearly all published reports Indicate DRLs reduce
multiple vehicle daytime crashes. Evidence about
DRLs effects on crashes comes from studies
conducted In Scandinavia,, Canada, and
the United States. A study examining the effect
of Norway's DRL law from 1980 to 1990, found a 10
percent decline in daytime multiple-vehicle crashes.
A Denmark study reported a 7 percent reduction
in DRL relevant crashes in the first 15 months
after DRL use was required and a 37 percent decline
in left-turn crashes. In a second study covering two
years and 9 months of Denmark's law, there was
a 6 percent reduction in daytime multiple-vehicle
crashes and a 34 percent reduction in left-turn crashes.
A 1994 Transport Canada study comparing 1990
model year vehicles with DRLs to 1989 vehicles without
them, found that DRLs reduced daytime multiple-vehicle
crashes by 11 percent.
In
the United States, a 1985 Institute study determined
that commercial fleet passenger vehicles modified
to operate with DRLs were involved in 7 percent fewer
daytime multiple-vehicle crashes than similar vehicles
without DRLs. A small-scale fleet study conducted
in the 1960s found an 18 percent lower daytime multiple-vehicle
crash rate for DRL-equipped vehicles. Multiparty daytime
crashes account for about half or all police-reported
crashes in the United States.
Where
are DRLs required?
Laws in Canada, Denmark,
Finland, Hungary, Iceland, Norway,
and Sweden require vehicles to operate
with lights on during the daytime. There are two types
of laws. Canada's requires vehicles to be equipped
with DRLs. The other type of law - in effect in Denmark,
Finland, Hungary, Iceland, Norway, and Sweden - requires
motorists to turn on their headlights if their
vehicles do not have automatic DRLs. This kind of
law applies to drivers only, and vehicles do not have
to be specially equipped. In 1972, Finland mandated
daytime running lights in winter on rural roads and
a decade later made DRLs mandatory year-round. Sweden's
Law took effect in 1977, Norway’s in 1986, Iceland’s
in 1988, and Denmark's in 1990. Hungary has
required drivers on rural roads to operate with vehicle
lights on since 1993. Canada requires DRLs for vehicles
made after December 1, 1989. No U.S. State mandates
DRLs, although some require drivers to operate vehicles
with lights on in bad weather.
Are
DRLs available on vehicles in the United States?
Offered on a handful of 1995 domestic and foreign
model passenger cars, pickups, and sport
utility vehicles, daytime running lights are becoming
a more common feature. They are standard on all 1996
Cadillacs, Geos, Saabs, Suzukis, Volkswagens, and
Volvos. They're also on Chevrolet’s Beretta, Cavalier,
Corsica, S-series
and C/K pickups, and Blazer, Suburban, and Tahoe;
GMC Jimmy, Sierra, Sonoma, Suburban, and Yukon; Isuzu
Hombre; Oldsmobile 88/LSS, 98, Achieva, Aurora, and
Bravada; Pontiac Bonneville, Grand Am, and Sunfire;
and Saturn sedans and wagons. They are options on
Land Rovers.
Why
has it taken so long to introduce DRLs in the United
States?
Some state lighting laws inadvertently prohibited
DRLs until the National Highway Traffic Safety
Administration (NHTSA agreed to permit automakers
to offer them on vehicles sold in all 50 states.
This action, which preempted the state laws,
followed a petition filed by General Motors. The Institute
had filed a similar petition based on studies showing
that DRLs are an inexpensive way to reduce daytime
collisions between vehicles. After initially granting
this petition, NHTSA terminated rulemaking in 1988,
saying that the matter wasn't clearly a national safety
issue and that auto manufacturers "tended to
oppose, rather than support, the proposal”. NHTSA
then changed course again, approving DRLs in 1993.
Will
DRLs be effective in the United States?
Countries where DRLs are required generally
have lower levels or ambient light during winter and
longer periods or dusk and dawn than the United States.
Although studies have indicated that DRLs have reduced
crashes in North America and Scandinavia, the impact
they will have on U.S. crashes has not been fully
determined since DRLs have been used only on a limited
basis here. Positive effects found in Canada1s
evaluation of DRLs are important because most or Canada's
population is at a lower latitude than Scandinavia.
Also, American DRLs are brighter than European DRLs.
This should increase visual contrast between vehicles
and their background despite brighter daylight conditions.
Will
DRLs shorten headlamp bulb life or lower fuel economy?
Running vehicle lights in the daytime does not significantly
shorten bulb life. Systems like those on General Motors
cars that use high beams are designed to operate at
half their normal power during daylight hours, thereby
conserving energy and reducing the effect on a vehicle's
fuel economy. NHTSA estimates that only a fraction
of a mile per gallon will be lost, depending on the
type of system used. General Motors estimates the
cost to be about $3 per year for the average driver.
Transport Canada estimates the extra annual fuel and
bulb replacement costs to be $3-15 for systems using
reduced-intensity headlights or other low-intensity
lights and more than $40 a year for DRL systems using
regular low-beam headlights. Automakers will not be
penalized for adding DRLs to their vehicles when they
are tested for compliance with U.S. federal fuel economy
standards. At NHTSA’ s request, the Environmental
Protection Agency has agreed to disconnect DRLs before
testing.
Will
motorists be bothered by glare?
Glare is not a major issue. NHTSA completed
a study to determine if drivers were bothered by glare
in their rearview and side-view mirrors from lights
of cars behind them. At 7,000 candela, the maximum
light intensity NHTSA set for DRLs, the steady light
intensity would be only about one-eighth the level
considered to cause discomfort. NHTSA tested vehicles
with DRLs using reduced-power high beams mounted no
higher than 34 inches. These are used on about 53
percent of Canadian vehicles and will be used in the
United States.
Are
motorcyclists required to have DRLs?
Federal law does not require motorcycles to have DRLs,
although all manufacturers voluntarily equip their
cycles with such lights. Some states including California
require the lights, and 22 states require motorcyclists
to ride with their headlights on at all hours.
INSURANCE
INSTITUTE FOR HIGHWAY SAFETY,
January 1996
1005 North Glebe, Arlington,
VA
22201 703-247-1500 FAX 703-247-16785
The
Insurance Institute for Highway Safety is an independent,
non-profit, scientific and educational organization
dedicated to reducing the losses - death, injuries
and property damage- from crashes on the nation’s
highways. The Institute is wholly supported by auto
insurers.
