Sener Ingenería y sistemas S.A

In the sixties and early seventies the number of fatalities due to accidents on the road networks increased markedly in many industrialised countries (World Health Organization 2009). Speed limits were in general introduced for all road types in most industrialized countries in 1970-1975 (Elvik et al. 2009). Speed limits affect the number of fatalities significantly in most cases and most developed countries have speed limits implemented today (Elvik, Christensen & Amundsen 2004, Elvik et al. 2009). An example illustrates the effect of introducing speed limits: in the United Kingdom no speed limits were set outside built-up areas until 1965 when a 70 mph speed limit was introduced (Safer Motor-

ings 2011). Despite a significant increase in the traffic volume over the next years, the number of fatalities did not reach the previ- ous level of the years around the introduc- tion of speed limits (Department for Trans- port 2002). Also, in Switzerland there was no speed limit outside built-up areas before 1973 (Swiss Federal Roads Office 2009). In Switzerland the introduction of gene- ral speed limits also resulted in a reduced number of fatalities (Swiss Federal Statisti- cal Office 2010). In Denmark the general speed limit was introduced in 1974 (Bur- chardt, Schønberg 2006). The safety effect due to the introduction of speed limits in the two latter countries is unclear because the Oil Crisis reduced the traffic volume in those years. However, when the traffic volume picked up again after the Oil Cri- sis, the change in the number of fatalities was disconnected from the change in traffic volume - exactly as it was found regarding the effect in the United Kingdom. The ef- fect of the introduction of speed limits on road fatalities is indicated in Figure 1.3. Despite the introduction of speed limits and the subsequently reduced number of fatalities, speed limit violating driving be- haviour is still widespread, also in coun- tries with a high road safety level as e.g. Sweden and Norway. In Sweden in 2004, it was found that only 43% of the distance driven on the national roads was driven without speed limit violations. And also that the average speed during speed viola- tions exceeded the speed limit by 10 km/h. These results largely agree with the results in most European countries (Vägverket 2008). A recent study, which, among other things, compares the proportion of speed- ing on roads in Scandinavia, found that

Figure 1.3. Development in number of fatalities in the United Kingdom, Switzerland, and Denmark, and the traffic volume in the United Kingdom1_{. Index numbers, 1970=100. Data regarding Switzerland were only}

found available from 1970 and onwards.

1 _{It seems reasonable that the development in traffic volume has been almost similar in the three countries.}

the majority of drivers exceeded the speed limits. On roads outside built-up areas the proportion was 45, 50, 55, and 71% for Norway, Sweden, Finland, and Denmark, respectively, while also significant propor- tions of drivers were found to be speeding on other road types. (Eksler, Popolizio & Allsop 2009)

The substantial amount of speeding can be explained by the fact that the reward of speeding is immediate: experienced re- duced transportation time. Hence it is easy for drivers to ignore or repress any speed- ing-related risk. Also, most people under- estimate their speed and what the road con- dition might allow. This phenomenon is found in several studies on speed choice as

well as on road safety (Várhelyi 1996). The result is a higher speed than if drivers were fully aware of the risks. Furthermore, in a modern car the feeling of speed is reduced due to e.g. less engine noise and wind re- sistance. In addition, there is a strong feel- ing of security. Even at high speeds, a mo- dern car feels stable and calm on the road. And this feeling is supported by equipment such as Anti-lock Braking System (ABS) and airbags, which might give the driver a false feeling of safety (Farmer et al. 1997). In addition, many drivers have a feeling of joy when driving at high speeds - this ap- plies especially to young male drivers, who might also find speed limits unnecessary (Harms et al. 2008, Mogensen 2002).

Moreover, one might say that traffic is a bad educator. That is due to the fact that e.g. an average Danish driver would have to drive for almost 800 years before he/she would be involved in a police-reported ac- cident causing severe injuries or fatalities in the car (Statistics Denmark 2010). Also Nilsson (2004) showed that an average Swedish car could drive in approximately 205 years before it would be involved in a police reported accident with injured. Finally, an Australian study tested the dan- ger of drink driving and of speeding. The suggestion was that a 10 km/h increase in speed increased the risk as much as a 0.05% level of alcohol (BAC) in the blood. However, there are absolutely no similari- ties between the penalty for speeding and drink driving although they involve the same level of risk. In both Australia and Sweden drink driving is punished more than 10 times more than speeding, which is just as dangerous (Kloeden et al. 1997). It is reasonable to assume that this is the case in most industrialised countries.

1.4 Traditional speed limiting