Automotive Lighting

Side marker lights are the only type of lighting required by the US FMVSS108 standard, but not by ECE regulations. Lighting functions that originated in the USA, for example centre high-mount stop lights (CHMSL) and daytime running lights (DRL), have typically been incorporated into ECE standards after a delay of a few years. In contrast, side marker lamps were made mandatory in the USA more than 40 years ago, but are still not required under ECE regulations. For this reason, it is important for us to consider the safety benefits of side illumination.

The safety aspects of side marker lights

From early 1969 onwards, the FMVSS108 standard required side marker lamps and reflectors to be fitted to all new vehicles on the US market. The effect on safety of this regulation was examined in 1983 in an NHTSA report. The study, which was entitled “An Evaluation of Side Marker Lamps for Cars, Trucks and Buses”, showed that every year in the USA side marker lamps prevent:


  • 106,000 accidents
  • 3,000 non-fatal injuries
  • 347 million dollars of property damage  


Despite these facts, there is no indication that consideration has been given over the last three decades to incorporating this requirement into ECE regulations. In the more recent history of road safety research, another reference has been made to the need for side illumination on vehicles. Dr. Mark Gonter analysed the increase in safety resulting from active lighting functions. His report highlights the following important facts:  


  • 21.6 % of nighttime accidents are caused by crossing traffic 
  • accidents at intersections in cities are the second most common type of serious accidents at night 
  • the number of accidents involving crossing traffic significantly increases at night in urban areas  


Both studies clearly indicate that side illumination on cars can reduce accidents and that the side visibility of vehicles in Europe needs to be improved at night. It is obvious that further studies will be required in order to update the existing information and to collect more data about the influence of side marker lights. In addition, investigations are needed into ways of improving the side illumination of vehicles. Important points for consideration in these studies include:  


  • mounting positions
  • light intensity and distribution
  • combination with side direction indicator (reciprocally incorporated?)
  • requirement for reflex-reflector
  • need of side illumination for detection purposes in autonomous driving
Mounting positions for side signal functions in ECE

The styling potential of side marker lamps

The two most recently introduced types of vehicle lights clearly demonstrate the potential for combining signalling systems with ambitious styling concepts. The CHMSL is an integral part of modern car design. It was first brought in around 25 years ago as an additional braking light and is now used by stylists as an integral design feature at the rear of the car, both when it is illuminated and when it is not. DRL offered even greater benefits for styling. The option of using the lights for brand recognition purposes was one of the driving forces behind the introduction of this safety feature. Side illumination offers similar possibilities for creating new styling concepts. Given the possible positions for mounting side marker lights, it is clear that this type of light has the potential to make a significant impact. The options include the number of single lamps that can be used and the variation in the light intensity, which can range from 0.6 to 25 cd.  

A wide variety of different styling possibilities are available. Each sketch shows only one possible option.

Other styling concepts can be used, for example, for elements such as areas or segments.

Although side illumination is mandatory only in the American FMVSS108 standard, there are very strong indications that it will be worthwhile to analyse the verifiable safety effect and incorporate similar requirements into the ECE regulations. Additional studies are needed to identify the design specifications, while the styling possibilities seem almost endless. In addition, new technologies such as LEDs and light guides will offer a broad variety of different options.