If the average speed on a road increases, crash risk also increases, as does the risk of a serious outcome. This is true in general terms, but more so when motorised vehicles crash with unprotected road users, such as pedestrians, cyclists and (light) moped riders. Furthermore, speed differences between vehicles at any one time or place are related to a higher crash risk.

Risky road user behaviour is behaviour that adversely affects road safety, such as driving under the influence of alcohol, drugs or medicines, speeding, inappropriate speed, distracted or fatigued driving, red light negation, and failure to use or misuse means of protection (motorcycle or moped helmet, seatbelt).

The mobile phone is symbolic of ‘distraction in traffic’. But apart from mobile phone calls, texting, or listening to music, many drivers, cyclists and pedestrians are occupied with all sorts of other activities that may distract them. Examples are: operating the navigation system, eating, drinking, talking to passengers or daydreaming.

Driving under the influence of drugs or impairing medicines reduces fitness to drive[i] and increases crash risk. Drugs have a numbing, stimulating or mind-altering effect on the brain, or a combination of these effects, which impair traffic task performance.

Driver fatigue is estimated to be a (contributing) factor in 15 to 20% of crashes, but estimates in individual studies vary widely. Drivers who are tired are less attentive and react less quickly and less adequately than drivers who are not tired. They also get irritated and frustrated more easily.

In this factsheet wrong-way driving is defined as ‘a car driving in the wrong direction on a road with separated driving directions and consequently driving into oncoming traffic '. This relates mainly to motorways. Wrong-way driving crashes are rare. The outcome, however, is often severe.

The weather has an influence on road safety. Weather conditions partly determine the road conditions and the driver's behaviour. Most studies into the relation between weather and road safety are about the situation during rainfall.