Exceeding the speed limit is a factor in the causation and severity of many road accidents. Speed limits are intended to assure safe operation of the road network by keeping traffic speeds to no more than the maximum that is appropriate for a given traffic environment. The speed of traffic also influences the flow of densely trafficked roads.

Voluntary speed assistance systems (SAS) are a means to support adherence to speed limits, by warning and/or effectively limiting the speed of the vehicle. The only technical requirements giving guidance for elements of such devices are laid down in UN/ECE Regulation 89, which is not mandatory in Europe. Those specifications are rather outdated and do not specifically apply to passenger cars.

Since 2009, Euro NCAP has rewarded manually set speed limitation devices (SLD) which meet the basic requirements of UN/ECE R89 but have additional functionality with regards to warning and set-at-speed.

In the meantime more advanced speed assistance systems have been introduced onto the market which are able to inform the driver of the current speed limit based on digital maps and/or camera based traffic sign recognition. Intelligent speed assistance (ISA) systems are expected to improve and will be more readily acceptable to the public. Hence, Euro NCAP has extended the SLD protocol to include the evaluation of the latest generation of intelligent speed assistance systems.

The work of Euro NCAP is soundly based on a synthesis of previous research findings regarding speed assistance systems, including Carsten et al., Oei and Polak, Biding and Lind and others. Functional requirements for the Speed Limit Information Function (SLIF), Manual Speed and Intelligent Speed Assistance systems (MSA and ISA) have been derived using input from various stakeholders. Recent experiences with Euro NCAP’s SLD assessment have been included. Besides functional requirements, a set of agreed driving manoeuvres has been defined, in particular to verify the driver-set limitation function. The draft procedures have been evaluated in a workshop with several commercially available and prototype systems.

Test and assessment protocols have been developed that contain specifications for different types of Speed Assistance Systems (SAS), SLIF up to full ISA systems where the SLIF is coupled with the warning and speed limitation function.

Points are available for all elements of SAS with additional points awarded to systems where the speed information is directly linked to the warning and speed limitation function.

The requirements specified in the developed protocols are not design restrictive, to allow the vehicle manufacturer to develop the systems to their best knowledge and experience. It is foreseen that, after a couple of years, Euro NCAP will tighten the requirements based on best practice. As more and more countries are introducing more strict speed managements systems the consumer demand for reliable and efficient SAS is expected to increase.