Equipment in vehicles to improve road safety can be seen as supplemental ap- proaches concurrent to traditional solutions. They are multifarious and can basically be divided into two groups: passive measures which lead to loss reduction that is equip- ment which reduces seriousness as much as possible in case of accidents; and active measures which lead to crash prevention in preventing any accidents from happening. It would take us too far afield to mention all
the types of equipment, which are available for a modern vehicle, but the following are a few of the most significant:
Passive measures could be seatbelt, seat- belt reminder, airbags, and e-call. Seat- belt use is mandatory in most countries, and all new cars and the majority of older cars are equipped with seatbelts. Wearing seatbelts significantly reduces the risk in case of an accident (Elvik et al. 2009). A seatbelt reminder warns the drivers if the seatbelt is not worn while driving, and it is found to have a statistically significant effect on usage (Regan et al. 2006a). Also, most new cars are equipped with airbags. It is one or several inflatable balloons, which will inflate rapidly if the vehicle de- celerates more than a certain level. Hence they help to protect the passengers from hard interior objects such as the steer- ing wheel, and they reduce accident da- mages significantly (Elvik et al. 2009). Finally, there is e-Call, which will consist of a Europe-wide, harmonised in-vehicle emergency call. In the event of a crash, the e-Call system in the vehicle involved transmits an emergency call directly to the nearest emergency dispatch centre. It can also be triggered manually. It has not been implemented so far but is planned to cover all Europe within a few years (European Parliament 2006). It is estimated to reduce the number of fatalities in the EU by 6-7% while the safety effect in densely popu- lated countries such as Denmark might be minor (Hellung Larsen 2007).
Active measures are a number of devices, which help the driver to avoid any acci- dents. Anti-lock Braking System (ABS) is one of the most widespread active mea- sures. It is a system that prevents the driver of a vehicle from blocking the wheels du- ring braking manoeuvres. It was scheduled to reduce the number of severe accidents, especially under bad weather conditions because it reduces braking distance signifi- cantly. Research results from the childhood of the ABS indicated that even though ABS can achieve a minor reduction in the number of injury accidents, it still results in an increase in the number of fatal ac- cidents. The increase was mainly due to more single vehicle accidents and a higher frequency of collision with fixed objects. It is likely that the problem with ABS was that it led to risk-compensating driving be- haviour such as higher speeds and more aggressive driving (Elvik et al. 2009)2.
Also Farmer (1997 and 2001) found that the safety effect of ABS is questionable. However, it is plausible that improved ABS technology and the fact that ABS is now fairly common in most vehicles in Western Europe has resulted in safety benefits from this measure which more than neutralise any risk-compensating driving behaviour. Another active measure, Electronic Stabi- lity Control (ESC) has a substantial posi- tive effect on road safety. In a study, Fergu- son (2007) found that the number of some types of fatal single accidents decreased by 30 to 90% when driving with ESC. Over- all, it is expected to reduce the total number
2 The 2009-version of the Handbook of Road Safety Measures includes only studies of the safety effects
from ABS, which are older than 2001.
of fatalities by 15 to 20% (eSafety Support 2010). Due to the significant safety effect it is now widely implemented in new cars and will probably be almost 100% imple- mented in most industrialised countries within a few years.
There are also a number of active systems, which aim to assist the driver in keeping appropriate driving behaviour in relation to the surrounding vehicles and road design (Bishop 2005). Following Distance Warn- ing (FDW) and Forward Collision Avoi- dance (FCA) are systems, which either warn the driver or intervene if the headway is too short (Bishop 2005). FDW results in significantly more appropriate distan- ces and fewer variations in the distance to the headway vehicle (Regan et al. 2006a). Lane Departure Warning warns the driver if the driver mistakenly begins to stray the vehicle out of the lane/road. It is supposed to have a significant safety effect, because it reduces the likelihood of head-on acci- dents and single accidents (Bishop 2005). Furthermore, there are some variants of Intelligent Cruise Control, which help the driver to set an appropriate speed. How- ever, if it works voluntarily, it has been found that many drivers increase the set speed above the speed limit (Jamson et al. 2006). On the other hand, if it works au- tonomously, resistance on the part of road users might be significant, which will be discussed later. These Intelligent Transport Systems (ITS), known as Advanced Driver Assistance Systems (ADAS), include In- telligent Speed Adaptation (ISA) (Carsten, Tate 2005) and will be elaborated on later.