||During the last decade, the number of motorcycles in Denmark has doubled. In 2005, 17
riders of motorcycles lost their lives on the Danish road network. This number increased
to 36 in 2007. This development has made headlines in the Danish press, and in the
press reports it has been suggested that this development arises from an overall
tendency, where an increasing number of elderly men have bought a motorcycle for
pleasure rather than a means of transport.
The official Danish objective is to reduce the annual number of fatalities in road traffic to
200 in 2012. While amounting for 5-6 % of injured in traffic for many years, motorcyclists
amounted for almost 9 % in 2007. Thus, improvements of motorcyclists’ safety becomes
more important in order to achieve the objective.
The aim of this thesis is to survey the Danish motorcycle riders in order to get an
understanding of the increasing number of motorcyclists’ accidents. First of all, I found
that very little statistics were available. As an example, the official estimate of
motorcyclists’ traffic volume is based on a survey from 1987, which simply has been
adjusted by the number of registered motorcycles since then.
At first, I made a survey of the age and gender distribution of motorcycle owners
compared to car owners. I found, that a motorcycle owner is typically a man, and that the
average age of the motorcycle owners increased significantly from 2002 to 2007. In
2002 41 % of the motorcycle owners were singles without children, while this group was
reduced to 35 % by 2007. Clearly, some changes has taken place in the social
characteristic of the people, who owns a motorcycle.
It was also observed that motorcyclists’ age has increased remarkably, and it is
noteworthy, that this increase is also seen the age of motorcyclists’ injured in traffic
accidents in the same period of years.
Motivated by these findings, I carried out a logistic regression analysis of the crash and
injury rates described by drivers’ social characteristics in a case-control setup comparing
motorcyclists to car drivers. The data used for the analysis were in microscopic scale. The
estimated model found that the parameters: age, sex, education level, family type and
motorcycle ownership all were significant predictors of crash involvement and injury in
traffic. I found that the odds-ratios for motorcycle owners compared to car drivers
significantly larger than one. While these results show that being a motorcyclist increase
risk of crash involvement and injury, the model does not take amount of driving into
Therefore, I collected a set of data from MOT-tests of motorcycles in the period 1997-
2005, in order to calculate the amount of traffic carried out by motorcycles. I found that
the annual mileage of a Danish motorcycle increased from 2522 km in 1997 to 2744 km
in 2004. I made a linear as well as a polynomial fit of the data in order to estimate the
average mileage of a Danish motor cycle in the years 2005-07.
Based on these data I was able to calculate the risk of a motorcycle rider being killed or
seriously injured per 10 mio km mileage. This risk decreased with some 50 % in the
period 1997-2001 but reached then a somewhat stable level. However, this stable level
is 38 times higher than the risk of being killed or seriously injured when driving a car
when evaluated for risks found for 2003.
A part of this huge difference may be related to the fact that a car driver is much more
protected than a motorcycle rider in the event of an accident. However, there may also be
differences in the way people drive cars and motorcycles.
Therefore data from speed measurements from eight locations on the major Danish
roads were analysed. The eight locations are distributed on different kinds of roads and
register the type of vehicle and the speed of the vehicle. At all eight locations motorcycles
had a higher speed than cars, and indeed the share of motorcyclists violating the speed
limits were much higher than the share of cars. Hence, I concluded that motorcycle riders
behave in a more risky way than car drivers.