What are Road Safety Risk Factors?
60 | MAKE ROADS SAFE ANNEX 1
WHAT ARE ROAD SAFETY RISK FACTORS?
Road Safety specialists frequently refer to risk factors. This note provides an explanation of the concept, and
its application to road trafic injury prevention. In con- sidering risk factors it is useful to use a categorisation
of primary and secondary risks. Primary risk describes the factors that contribute to
the risk of occurrence of a road crash: •
Exposure •
Behavioural factors •
Road environment •
Vehicle factors. Secondary risk includes the likelihood of injury occur-
ring and its severity: •
Vulnerability of certain modes of transport •
Vehicle factors •
Use of safety devices •
Behavioural factors •
Road environment •
Post-crash medical care.
Primary risk
Exposure
In road safety terms, exposure is usually taken to re- fer to the amount of travel undertaken, deined as the
number of trips, the distance travelled, or time in the road environment. However, when considering glo-
bal comparative risk and trends in risk, several other factors are relevant. Economic development, and the
accompanying rise in the number of motor vehicles and the amount of motorised trafic, are key determi-
nates of risk of trafic injury. The quality of the road network, the mix of types of trafic, and the extent of
public transport and facilities for more vulnerable road users such as pedestrians and cyclists, all contribute
to the level of risk for any given trafic volume. Whilst car ownership is increasing rapidly as incomes rise
in developing countries, for the majority, vulnerable transport modes remain their only option.
In low income and middle income countries, rapid growth in motorisation, especially two wheeled motor
vehicles, has not been accompanied by suficient im- provements in the road environment to allow for such
growth to take place without an increase in the rate of road trafic crashes. Although similar problems were
faced in high income countries when their motorisa- tion increased rapidly in the 1950’s and 1960’s, their
per capita incomes were high enough to allow for concurrent road investment, and the mix of trafic was
much less varied than the present situation in low in- come and middle income countries. Hence, since the
1970’s, and notwithstanding continued trafic growth, fatality rates in high income countries have tended to
decrease, and in many countries in Western Europe the number of fatalities has also declined. The chal-
lenge now is to assist such a transition in low income and middle income countries, so that much needed
economic development is not paid for through human tragedy.
Behavioural factors
Human behaviour makes a direct contribution to crash risk through the extent of knowledge and understand-
ing of trafic systems, driver experience and skill, and the relationship between risk and factors such as
speed choice and alcohol consumption. Attitudes to risk, and in particular recognition of the vulnerability
of non-motorised modes, are also determinates of crash rates. In all countries, inexperienced drivers
are relatively high-risk drivers, and it follows that in newly motorised societies the risk is increased by the
relatively high proportion of new drivers in the driving population. Where this growth is accompanied by in-
adequate driver training and testing regimes, the risk is further increased.
Excess or inappropriate speed is a key contributor to crash risk. Speed choice is inluenced by the legal
speed limit, but also by road layout, trafic density, road surface condition, and the level of enforcement
of speed limits. There is still a lack of acceptance amongst drivers, even in high income countries where