Recent coverage of DRLs in Driving Vision News and elsewhere indicates that there are still questions among the international driving communityabout the potential benefits of DRLs, resulting in a substantial lack of agreement among regulations even when they are specified.
Indeed there is enough interest and debate to sustain a session on DRLs and conspicuity functions at the upcoming ISAL meeting in Darmstadt this fall. Among the papers in that session will be one from the LRC at Rensselaer Polytechnic Institute describing some studies supported by the members of the Transportation Lighting Alliance .
The LRC/TLA paper builds on an earlier paper presented at the 2010 V.I.S.I.O.N. symposium in which daytime and nighttime multi-vehicle crash data for rainy and clear weather were presented for the state of California, which in the past decade enacted laws requiring use of the headlamps whenever the windshield wipers are required. There were substantial reductions in crashes after enactment of the new law for daytime and dawn/dusk crashes in rainy weather. And without giving too much away, there appears to be agreement between crash data for additional states and published models of visual conspicuity, suggesting a clear mechanism for the benefit of daytime use of headlamps during rain.
This is especially exciting because our ongoing research focus is to identify the relevant visual parameters that can be used to confidently predict safety in terms of vehicle crashes. The ability to predict is key because it allows the lighting community not just to identify, but to shape better lighting for safety rather than wait several years after the introduction of a new technology to see if it made a difference. Studies of crash data are notoriously difficult to work with because crashes are rare (thankfully) and subject to many factors beyond vision. But crash studies are necessary because after all, crashes are the hard currency of safety and preventing them is the reason we have lighting in the first place. Establishing firm links between lighting/vision parameters and crashes is the most promising way to accomplish safety with lighting.
Obviously, a study of rainy-weather daytime crashes is not the same as DRLs, but it is an analogous situation, because the reason headlights in rainy weather in the daytime should improve safety, is the increased conspicuity they provide. So I think our study of “wipers-on, headlamps-on” is very relevant to DRLs, although many more questions remain regarding the appropriate intensities for varied terrain and how they should be specified. The DRL/conspicuity session of ISAL 2011 will be an excellent opportunity to hear varied perspectives on these issues.
