I first began to notice these lamps on new Audi cars in 2010 and unhesitantingly disliked them due to the visual discomfort caused. Over the years since, I’ve sporadically researched them on the internet. I’ve learned of a list of harms identified by other people unrealised by me and also better understand the various ways they diminish my safety and enjoyment of being a road user.
The single worst property of Day Running Lamps (DRL) is that they are far too bright at 400-1200cd! This is in accordance with a United Nations standard (UNECE Regulation 87 Revision 2) which has been mandated in member states by the European Union. That this form of DRL offends me is ironic because since I began driving, I’ve readily illuminated my vehicle’s sidelights (being 50cd) when the natural light level has been low. The UNECE specifies such a high brightness because they intend that DRL be conspicuous under blazing midday sunlight! That’s “wrong-headed” because if mandatory DRL bring any safety gain at all (and that’s uncertain), it’s greatest in subdued light where they would be conspicuous at a brightness not exceeding 150cd!
This very poor decision in 2008 by the UNECE to allow DRL brightness of upto 1200cd is inconsistent with historical positions taken by many government and industry organisations worldwide in preceding decades. In 1977, Sweden (the home of Volvo) mandated (incandescent) DRL of 21 Watts which approximates to 500cd. In 2003, research in Japan recommended DRL be 200cd.
I oppose the huge over-brightness in UNECE’s standard for DRL because:
# By over-stimulating points on an observer’s retinas those parts suffer “white-out” for a number of seconds – and in some individuals over a minute. Until (spontaneous) recovery takes place the observer has “blind-spots” at the corresponding points in their view. The scientific terms for this effect are “scotomatic retinal disablement" or "retinal bleaching". This effect becomes increasingly severe the duller the ambient light because an observer’s iris opens in reaction, allowing a greater proportion of the light from a DRL into their eyes. There cannot be an safety advantage from causing impaired vision in road users (especially drivers) albeit incompletely and temporarily. Personally, this is the ill-effect of DRL that I experience most frequently.
# Each such lamp obscures the scene in its immediate vicinity, formally called “disability glare”. It’s this effect that makes an activated (amber) turn signal lamp difficult to discern, if it’s mounted adjacent to a DRL. Some vehicle manufacturers with such designs have programmed the adjacent DRL to dim (e.g. Audi & Porsche) or to extinguish (e.g. Jeep) in recognition of this ill-effect. I regard that programming not as a mitigation but as an acknowledgement of glaring DRL!
# In lower ambient light levels (e.g. when it’s overcast, dawn or dusk) the great disparity in brightness between a driver’s view of the general scene and the DRL in that scene can cause psychological discomfort or physical discomfort. These may be expressed by a driver needing to avert their gaze further away from approaching vehicles’ DRL than straight ahead, subtracting from the forward vision optimal for safety.
# Such DRL tend - as was envisaged - to draw road users’ attention. The problem with doing so, is that the other elements (and hazards) in the scene which a driver must observe and perceive effectively (e.g. road signs/markings, bends, potholes, horses, cyclists, pedestrians) therefore each receive a smaller portion of a driver’s finite attention though - for accident minimisation - those are no less worthy of receiving it.
You can read more of the case against (High-Intensity Discharge headlamps and) Day Running Lamps on the UK-based Lightmare campaign website, www.lightmare.org/Effect_on_vision.htm.
If you would support a reduction in the maximum brightness of DRL and HID headlamps, you can state it publicly at Lightmare’s online petition and tell your MEPs the same via this website, www.writetothem.com.
I invite forum members to comment on DRL in this thread. To quantify their negative impact on me, I will state that I experienced some sort of ill-effect of DRL, during December 2014 on 10 occasions.
