The question whether self-driving vehicles will improve road safety cannot be answered with a simple ‘ yes’ or ‘no’. For, the consequences of incorporating self-driving vehicles into road traffic are not exactly clear.
In principle, self-driving vehicles could reduce crash risk, because the risk of human failure could substantially decrease. Typical human errors that may cause crashes are made in the following areas: 1) recognition (e.g. inattentiveness), 2) decision making (e.g. aggressive driver behaviour), 3) performance (e.g. inaccurate steering), or 4) no performance at all (e.g. falling asleep) [6]. In preventing these crash causes due to vehicle automation taking over driving control, the number of crashes could, in theory, substantially decrease. However, self-driving vehicles could also result in new safety concerns, preventing road safety improvement or even worse increasing unsafety. This concern will particularly be relevant to vehicles that are only partly self-driving [7]. In such a vehicle, the driver continuously needs to be alert in order to intervene or take over control when the vehicle cannot manage road conditions anymore. Yet, road users have trouble monitoring the environment continuously and adequately, and therefore find it hard to take over control when this is called for [8]. Other potential problems are that drivers may unduly rely on the system or think that the system will offer support when this is not the case. Other – external – safety risks concern cyber attacks and software vulnerabilities which may keep the system from functioning [7]. In addition, problems could arise due to system errors, for instance because of algorithm malfunctioning or faulty sensors.
There are numerous potential safety effects of self-driving vehicles that have only been researched to a relatively limited extent. Increased use of self-driving vehicles could, for instance, result in more vehicles on the road, which would increase mobility and, thus, the number of crashes. A favourable effect on road safety could arise if self-driving cars were to be used for car sharing. Such a shared self-driving car could take a passenger from A to B and then drive on to transport another passenger. If a lot of self-driving cars were shared and people forfeited their own cars, fewer car parks would be needed. The freed-up space could then be used to redesign roads to improve road safety, for example by widening bicycle paths/lanes to make them safer.
