Organisation: TRL
Date of Publication: December 2022
Uploaded to Knowledge Centre: 18 April 2023
E-scooter use is increasing, and with it, the number of collisions involving e-scooters. The rapid rate of uptake of devices has resulted in a gap in the reference data available for collision investigators to make use of in reconstructing collisions, data which is commonly available for other collision types.
The main aim of this study was to consider the capabilities of privately owned devices likely to be
encountered in ‘real world’ collision scenarios and examine whether manufacturer-published data is realistic. Common characteristics and observations relevant to collision investigations were also
recorded. A sample of donated, used devices was tested to determine the acceleration, deceleration and peak speed characteristics of different types of device.
It was found that:
- Mean acceleration across all devices was 2.82ms-2 with a standard deviation of 1.14ms-2
- The strongest predictor of acceleration capability was motor size, with 500W devices having a mean acceleration around 2ms-2 greater than the 250 – 350W devices.
- Increasing rider mass produced inconsistent variations to acceleration. This is an area which warrants further study, particularly in relation to devices being ridden with a second rider instead of a heavier single rider.
- The effect of tyre pressure variation on acceleration was inconsistent.
- All devices were found to over-state their peak speed. Where fitted, speedometer readings over-stated true speeds by 2.5 – 5km/h, and peak speeds were found to be between 1.5 and 11km/h lower than manufacturer-stated maxim values.
- Deceleration rates across the sample were more consistent. The mean result for the whole sample was 3.43ms-2 or 0.350g (standard deviation 0.53ms-2).
- Devices with disc brakes produced slightly higher decelerations than drum brakes and decelerations were greatest overall when using foot brakes (although with a significantly smaller sample).
- Wheel lock up was delayed or prevented when the rider was weighted, resulting in lower average deceleration rates.
In addition to these objective test results, assessment of the sample of e-scooters highlighted a
number of maintenance issues which may be encountered among privately owned devices. In the
sample, more than 50% of devices had brakes or steering in unserviceable condition, and 40% had
broken or missing rear mudguards, often resulting in loss of the rear light assembly. Tyre
maintenance was a common problem, with an average under-inflation of pneumatic tyres of 55%
observed.
Lastly, in some exploratory stability and handling tests we found that vertical obstructions of up to
40mm could be mounted without destabilising the rider. Whether higher obstructions will have
destabilising effects is partly dependent on the angle of approach, but predominantly dependent on rider input. The likelihood of destabilisation will rely on the rider’s skill and experience. This is also true of swerve manoeuvres. Specific conditions for creating destabilisation and falls were not
quantified in this study.
The study has produced a set of reasonable reference data that can be referred to in reconstructions of collisions. Although a number of areas worthy of further investigation have been identified, across general categories of acceleration and deceleration, consistent results were found. The study also highlighted relevant observations such as those relating to device condition and handling, which will be worthy of consideration when investigating e-scooter collisions.
Click the following link to view the full report:
https://mcusercontent.com/e31ae4ccb161b26b48f29468d/files/69a11740-598b-13f2-d014-50d19ddbec71/ACA104_In_Depth_Investigation_of_E_Scooter_Performance.pdf