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The front brake lamp must be considered as a light-signalling function LSF (from the term light-signalling function) with a light intensity comparable to other LSFs on vehicles, since a version with a lower light intensity would not be suitable for the purpose.
Since other colours are already legally assigned to specific situations or to specific types of vehicles, only the use of green or white is an option.
Given the already existing high number and range of variations of forward-facing white light signals (low beam, high beam, fog lamps, etc.), the use of a white front brake light could contribute to the reception of ambiguous information, thereby nullifying its contribution to road safety.
In addition, this colour is well known from the road traffic environment (e.g. traffic lights). Compared to other colours, the green colour, for the purpose of the front brake light, is also supported by psychological considerations, especially as regards the red colour.
It is assumed that the front brake light will be connected directly to the rear brake light and therefore only one additional device needs to be connected to otherwise identical circuits in the control unit(s).
The European Parliament's report Saving Lives: making the EU safer for cars, published in 2017 as part of a major review of means and requirements to improve road safety, highlights that:
"In order to improve road safety, the perception of slowing vehicles by other road users should be facilitated by the use of clear signal lights on vehicles. The mandatory use of emergency braking indicators in the form of flashing brake lights or flashing warning lights is expected." [no. 37].
The mention of signal lights for signalling deceleration in general, which is not limited to emergency braking, gives a strong indication of the need for permanent and regular front signalling, given that rear signalling of deceleration has been around for a long time.
The present concept of a front brake light is therefore fully in line with these stated objectives, particularly since the use of the colour green provides the required uniqueness of signal.
At the same time, future requirements for mandatory driver assistance systems were mentioned in this report. Although the introduction of front brake lights is currently only planned on a voluntary basis, it can be concluded from this report that a system meeting these requirements is in line with the EU's objectives, in particular because: