Not much is known about causes and effects of submerged vehicle crashes in the Netherlands. Yet, on the basis of foreign research, something can be said about factors that may be at play. We should bear in mind that it is unclear to what extent these factors are also relevant for the Netherlands.
Drowning
Although drowning does not cause crashes, it is the reason why submerged vehicle crashes often end badly and end up in crash statistics. (Foreign) research shows that most casualties in submerged vehicle crashes do not have injuries that should preclude escape [2] [3] [4]. These casualties could most probably have survived the crash if they had not drowned. Car occupants are most at risk of death by drowning on account of the wrong choices made in panic [1]. Instead of a speedy exit through the car window, they will call emergency services, try to open doors (whether or not by first waiting for the car to fill), or hope that an air bubble in the car will save them. Being unable to swim or not knowing what to do are other possible problems. In addition, ending up in the water inside one’s vehicle is very stressful. The longer one stays put, the more psychological stress will increase. This will result in hyperactivity, hypoactivity and/or inefficient decision-making [6].
Alcohol and drugs
It is unknown what part alcohol plays in submerged vehicle crashes in the Netherlands. A Swedish study showed that, in these crashes, 32% of drivers were under the influence of alcohol with an average level of 1,8g/L (three times the legal limit). In addition, 28% of drivers were under the influence of drugs [2]. In two American studies, different percentages were found: a 2011 study found 44% were drink-driving [7] and a 1990 study even found that 74% had consumed alcohol [4].
Speed
Direct information about the role of speeding in submerged vehicle crashes is missing. A Swedish study did however show that, in 10 out of 64 studied submerged vehicle crashes, guard rails did not provide sufficient protection when cars drove at too high speeds [2].
Causes of submerged bicycle crashes
According to the paragraph What are the characteristics of submerged vehicle crashes? , a significant share of fatalities (almost 10 a year) was cycling when ending up in the water. Unfortunately, it is unknown under what circumstances they ended up in the water and why they could not reach safety. Foreign research does not provide this information about cyclists either.
Causes of submerged mobility scooter crashes
In-depth research into mobility scooter crashes in the Netherlands shows that a rather large share (one seventh) is involved in a submerged vehicle crasht [8] [9]. These crashes occur because the mobility scooter user is startled into accelerating instead of braking. This usually happens during special manoeuvres such as parallel parking. Once in a while, a mobility scooter user is forced to brake for a vehicle in front, but mistakenly accelerates instead and is forced to swerve and subsequently hits the water. The in-depth study showed the crash outcomes to be limited to, at most, minor injuries (MAIS score 1), since casualties are helped to safety by bystanders.
