Press release

Each year, 45 road deaths and 600 injured can be saved in the Netherlands if cars keep their lights on during daylight hours, thus making them more visible. This is the result of SWOV estimates based on research carried out in a number of EU countries for the European Commission. The Institute for Road Safety Research SWOV and the Netherlands Organization for Applied Scientific Research TNO represented the Netherlands.

Not having seen the other road user plays an important roll in 50-80% of road crashes. By driving with their lights on during daylight hours (known as Daytime Running Lights or DRL), motorists increase their visibility. Doing this can prevent crashes. Other road users estimate vehicles with DRL as being closer than they really are. This results in taking less risk when overtaking and approaching an intersection. In comparison with the current situation, SWOV expects this to result in 15% less deaths, 10% less severely injured, and 5% less slightly injured. Based on the 2003 crash data, the introduction in the Netherlands could save about 45 road deaths.
DRL is already obligatory, sometimes in a more limited version, in various European countries.

Ways of introduction
We studied various ways of introducing DRL:

1. Only a behaviour measure: motorists are obliged to turn their front dipped headlights on during daytime.
2. The behaviour measure with also an obligatory automatic DRL switch in new cars.
3. The behaviour measure with also an obligatory advanced DRL unit in new cars.
4. No behaviour measure, but with an obligatory automatic DRL switch in new cars.
5. No behaviour measure, but with an obligatory advanced DRL unit in new cars.

We examined the relation between benefits (crashes, casualties) and costs (air pollution, extra fuel consumption, and advanced DRL units). This showed scenario 3 to have the most positive cost-benefit ratio.
Based on this, the research institutes recommend choosing a general DRL obligation and fitting out new cars with an advanced DRL unit. Among other things, such a unit contains a special sensor that, at twilight, switches automatically over from the minimum DRL basic lights to dipped headlights plus other lighting. In this variation, the benefits exceed the costs by a factor of 1.7.

No negative effect for other road users
An often-heard argument against DRL is that other road users will be less conspicuous in the vicinity of a car with DRL. No indications of this were found in the EU study. There is virtually no masking effect where, for example, pedestrians and cyclists are less visible because of DRL. Nor are there any indications that motorcyclists, who already often have their lights on in daytime, suffer any effects of this measure.

Pollution effects
The greater energy use will increase both the fuel consumption and CO2 emission by an average of 1%. This can increase to 3% for fuel-efficient cars. These negative effects can be reduced considerably if the advanced DRL unit is chosen. These have special DRL lamps with a lower wattage or LED lights. The rear lights can also be turned off during the daytime to save fuel.

The research institutes reported the results to the European Commission, who announced seriously considering concrete proposals for

There is a Fact Sheet about Daytime running lights, and it can be accessed on SWOV's website.