Traffic congestion occurs when traffic demand exceeds road capacity, or when an incident such as a traffic crash, a vehicle breakdown occurs or temporary roadworks take place, all of which temporarily reduce capacity and restrict traffic flow. Congestion crashes mainly occur at the tail end of a traffic jam. There, the speed of the traffic flow decreases sharply, which coincides with frequent and hard braking, and with a high risk of rear-end crashes.

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. Drivers that maintain a speed that is higher than the average speed on that road run a higher crash risk; drivers that maintain a speed that is lower than average do not.

In 2020, over a quarter of the total number of bicycle kilometres were cycled on pedelecs; particularly the over-65s opt for pedelecs. This is also borne out by the crash figures: in 2019 and 2020, almost one in three of the cyclist fatalities was a pedelec rider.

In 2016, there were 189 road deaths among cyclists in the Netherlands. This is approximately 30% of the total number of road deaths. The number of seriously injured cyclists is not exactly known. Their number in 2015 was estimated to be more than 60% of the total number of serious road injuries, which would be over 13 thousand. A large proportion of the seriously injured cyclists is the result of a single bicycle crash, a crash in which no other road user is directly involved.

A safe infrastructure is of vital importance to pedestrians and cyclists. In 2010-2019, 40% of the number of road deaths were pedestrians or cyclists. In 2018, they even made up 69% of the number of seriously injured road users. If pedestrians or cyclists are involved in crashes with motorised vehicles driving faster than 30km/h, they run a significant risk of severe or fatal injuries. The design of residential areas and homezones should therefore ensure that driving speed does not exceed 30km/h.

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. Most wrong-way driving crashes occur when a driver enters a motorway exit ramp or when a driver reverses direction on a motorway. Orientation problems (especially among the elderly) or recklessness (especially among young drivers) are the most common causes.

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). Younger road users more often display risky behaviour than older road users, and men more often than women.

In the Netherlands, on average, more than 50 people die every year in a submerged vehicle crash. More than two thirds die from drowning. The casualties are mainly car occupants, while cyclist and mobility scooter fatalities are also numerous. Casualties are mostly male and aged 18-24. Despite the large number of casualties, not much is known about possible causes of crashes in which vehicles end up in the water. Foreign studies show that alcohol and drug use, and/or speeding are often involved.

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.

A bicycle helmet is intended to protect cyclists against head and brain injuries when they are involved in crashes. The helmet does not prevent bicycle crashes (see the SWOV fact sheet Cyclists for general bicycle safety measures). International research shows that in case of a crash helmeted cyclists are 60% less likely to sustain serious head/brain injuries and 70% less likely to sustain fatal head/brain injuries than cyclists not wearing a helmet.