Common causes and scenarios of mobility scooter crashes are: incorrect use of the throttle (squeezing instead of releasing), tipping of the often unstable mobility scooter because of unevenness of the road surface, bumping into a kerb or passing halfway across a kerb, a sudden swerving manoeuvre, or an intentional or unintentional priority error. There are no data available about the (concurrent) causes of crashes with enclosed disability vehicles and microcars.
The in-depth SWOV study of mobility scooter crashes   distinguished four crash types which could describe 32 of the 35 crashes studied. They involve a combination of the conflict type and some decisive crash factors. The crash types are:
1. Mobility scooter user squeezes the throttle to brake, whereas it should have been released, and ends up in the water (n = 5). The vehicle design is conducive to the crash: a different mode of operation might have prevented the crash.
2. The mobility scooter gets out of balance after contact with an obstacle or bump, which causes the user to take a fall (n = 8). This crash type is caused by infrastructural factors combined with the instability of mostly three-wheeled mobility scooters: narrow bicycle tracks and sharp bends impede manoeuvring and contact with e.g. a kerb makes the mobility scooter tip over.
3. Swerving manoeuvre of the mobility scooter user prevents a collision, but results in the user taking a fall (n = 8). User behaviour also plays a part here, in combination with the vehicle instability: the mobility scooter user tries to prevent a collision by an abrupt steering manoeuvre. A collision is indeed prevented, but the vehicle is so unbalanced that it tips over.
4. A mobility scooter user crosses the road or continues straight on and collides with crossing motorised traffic regardless of who has priority (n = 11). Again, behaviourial factors are involved: either the driver of the car or the user of the mobility scooter wrongly denies right of way, for example because the other road user is overlooked (insufficient visibility, distraction?).
In a study by VeiligheidNL  115 ER-treated casualties of mobility scooter crashes were asked to indicate which factors triggered the occurrence of their crashes which took place in 2011. Figure 6 shows which of the 11 causes were chosen by what percentage of respondents (respondents could choose more than one factor; on average they chose 1.5 factors).
Figure 6. Factors that caused or contributed to the mobility scooter crash. Source: