Impact of Adaptive Front-lighting Systems (AFS) on road safety: Evidences and open points

Abstract

Almost four years after the entry into force of Regulation ECE 123 on Adaptive Front-lighting Systems (AFS) for motor vehicles, and once the first cars bearing them start to circulate, a comparison between the original idea of AFS and their potential impact in safety and accident prevention is possible. In this work, we present the basic concepts of this new way to light roads and analyse some unforeseen consequences that might arise within the ECE regulatory framework once the presence of AFS becomes massive. This paper also pretends to be an useful guide for some countries like China, still considering the best way to definitively regulate these complex systems whose impact on road safety is expected to be huge.

Introduction

Although only a small part of travels by car are carried out after the sunset, 40% of fatal and serious injuries take place during night-time (Ward et al., 2005). Given that public lighting is mainly limited to urban areas, this figure gives us a significative idea of how deep the impact of accurate vehicle lighting is. Accurate vehicle lighting is not achieved only with levels of illumination according to the visual task of driving, but also with a strict control of glare, which can be even more dangerous than low levels of illumination.

The remarks above remind us that the final objective of vehicle lighting is to see and to be seen. This target has encouraged lighting and car manufacturers to continuously improve and innovate their lighting systems in order to make driving safer.

Hence, among the large amount of advances in vehicle lighting during the last years (Daytime Running Lamps, use of Light Emitting Diodes (LED), Cornering Lamps and many other), there is one that will change our way to understand automotive lighting and even vehicles themselves: the introduction of the Adaptive Front-lighting Systems (AFS).

Although the main target of AFS is easy to understand (adapt headlamp illumination to some given driving conditions), the complexity of these systems requests a precise definition of what an AFS is. In this sense, the regulatory framework in the UNECE countries, that is, those belonging to the United Nations Economic Commission for Europe and also in Japan, provides rigorous definitions of such systems and the large variety of related concepts.

Within this regulatory framework, commonly known as ECE Regulations, AFS are described in detail in Regulation ECE 123 (2008) and the relevant amendments to Regulation ECE 48 (2008) that came into force after May 2008.

Hence, Regulation ECE 123 defines an Adaptive Front-lighting System (or just “system”) as a lighting device, providing beams with differing characteristics for automatic adaptation to varying conditions of use of the passing beam and, if it applies, the main beam with a minimum functional content, which will be described in the next section. According to this Regulation, such systems consist of the “system control”, one or more “supply and operating devices”, if any, and the “installation units” of the right and of the left side of the vehicle.

The situation in USA and Canada is less complex because the variety of cases and situations is not so exhaustively described as in ECE. The Society of American Engineers (SAE), in Standard SAE J2591 (2008), defines an “Adaptive Forward Lighting System” (note the slight difference in the denominations between ECE Regulations and SAE standards), as a forward lighting system intended to adapt a forward lighting device’s beam pattern to improve driver visibility based on inputs such as vehicle speed, road geometry, and/or environmental conditions. The system is comprised of one or more forward lighting devices and the entirety of components required to control and operate the devices.

Anyhow, this paper is focussed in the impact of AFS in the ECE area, and comparations with the North American regulatory framework will be scarcely mentioned and only with the aim of highlighting some important differences.

The remarks above give us an idea about the complexity of AFS. If we also consider the huge amount of factors taking place in road safety and the fact that most of the research on AFS has been exclusively focussed on the bending light systems (Rumar, 1997, Sivak et al., 2005a, Sivak et al., 2005b, Sullivan and Flannagan, 2006), but not in the “new” AFS classes (E, V W), we find that the impact of these systems on road safety is a rather unexplored field yet.