# Micromobility braking performance in real-world safety-critical events from naturalistic data

Claire Naude, Ebrahim Riahi, Bastien Canu, Thierry Serre

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## ► To cite this version:

Claire Naude, Ebrahim Riahi, Bastien Canu, Thierry Serre. Micromobility braking performance in real-world safety-critical events from naturalistic data. International Co-operation on Theories and Concepts in Traffic Safety (ICTCT), Oct 2025, Berlin, Germany. hal-05382910

HAL Id: hal-05382910

https://univ-eiffel.hal.science/hal-05382910v1

Submitted on 26 Nov 2025

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# Micromobility braking performance in real-world safety-critical events from naturalistic data

¹*Naude, C., ¹Riahi, E., ¹Canu, B. & ¹Serre, T.

¹claire.naude@univ-eiffel.fr, Gustave Eiffel University, France

**Key words:** naturalistic driving data, braking performance, risky situations, safety

## Introduction

Recent years have seen a proliferation of micro-mobility vehicles in urban environments, with these vehicles' vulnerable users experiencing an increased incidence of involvement in accidents. In the event of an emergency, it is important to consider the vehicles' capacity to enable avoidance. While previous studies have established the braking performances of these vehicles through controlled track tests, revealing notably low efficiency for e-scooters and e-monowheels, there remains a critical need to examine their real-world performance. This study aims to bridge this gap by investigating the braking capabilities of e-scooters, e-monowheels, and e-bikes in authentic dangerous urban scenarios.

## Material and methods

A total of 143 participants, consisting of 56 e-scooter riders, 24 e-monowheel users, and 63 e-bike riders, were tracked over two-month periods, covering all daily journeys, in three different regions of France: South (Marseille and small surrounding cities, Oct-Nov 2022), East (Lyon, May-June 2023) and Centre (Paris, Nov-Dec 2023). Data collection utilized removable smartphones as recorders, secured in 3D-printed supports on e-scooters and e-bike handlebars, and placed in chest harnesses for e-monowheel users. A dedicated application captured: GPS position and speed (1 Hz), accelerations and rotation velocities (100 Hz), and video of the scene ahead (30 fps). Riders reported real time risky situations, including dangerous interactions with other road users, infrastructure issues, and their own behaviour. Subsequent analysis identified braking manoeuvres when present, and extracted mean deceleration level during braking from filtered longitudinal acceleration data.

## Results

From 7,365 recorded trips covering a total traveling distance of approximately 26,000 km, participants reported 645 risky events that could be identified in the data, 385 of which involved braking (Table 1).

<table><caption>Table 1. Available data</caption><thead><tr><td>Vehicle</td><td>e-scooter</td><td>e-monowheel</td><td>e-bike</td><td>total</td></tr></thead><tbody><tr><td>N. trips</td><td>2,745</td><td>1,471</td><td>3,149</td><td>7,365</td></tr><tr><td>Distance (km)</td><td>6,083</td><td>6,504</td><td>13,404</td><td>25,991</td></tr><tr><td>Duration (h)</td><td>401</td><td>410</td><td>831</td><td>1,642</td></tr><tr><td>N. found reported risky events</td><td>209</td><td>134</td><td>302</td><td>645</td></tr><tr><td>N. risky events involving a braking</td><td>117</td><td>83</td><td>185</td><td>385</td></tr></tbody></table>

Figure 1 shows the deceleration distribution for each rider type during these events.
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<figure><img src="image_5.png" /><figcaption>Figure 1. Decelerations in risky situations</figcaption></figure>

Average deceleration in reported risky situations was 4.3 m/s² for e-scooter compared to 3.0 m/s² for e-monowheels and 3.6 m/s² for e-bike. Pairwise t-tests confirmed significant differences between these averages.

Comparison of these real-world braking performances to track test results evaluating deceleration capacity in hard braking (Naude et al., 2023) reveals that e-scooter deceleration is slightly higher in safety-critical events than in controlled hard braking tests, while e-monowheel performance remains similar in both scenarios (Table 2). Conversely, e-bike users brake less intensely in real risk situations than in track tests, rarely using their bike's maximum braking capacity. The naturalistic study showed greater value dispersion due to varied situations, from emergency to moderate braking, and differing vehicle braking capacities.

<table><caption>Table 2. Comparison of braking performances between track test and naturalistic driving risky situations</caption><thead><tr><th>Average deceleration (m/s²) [Standard Deviation]</th><th>e-scooter</th><th>e-monowheel</th><th>e-bike</th></tr></thead><tbody><tr><td>Braking in risky events during naturalistic study</td><td>4.4 [1.5]</td><td>2.9 [2.3]</td><td>3.8 [1.2]</td></tr><tr><td>Hard Braking on track</td><td>3.7 [0.3]</td><td>3.1 [0.3]</td><td>6.1 [1.0]</td></tr></tbody></table>

## Conclusions

The methodology enabled a comprehensive examination of real-world braking performance and safety issues across various micro-mobility vehicles in different urban environments. Analysis of 385 reported risky events involving braking revealed that electromobility vehicles have significantly lower deceleration levels (3-4.4 m/s² on average) compared to cars or motorbikes (8 m/s²). These findings align with track performance studies, except for e-bike users who rarely utilize their vehicles' full braking capacity. Future research should focus on detecting all sudden braking events in natural traffic to include undeclared risk situations and common braking manoeuvres.
The low actual braking performance of these vehicles in high-risk situations may explain their higher accident risk, especially given their capability to travel at much higher speeds than conventional personal transport devices. This underscores the need for improved safety measures, enhanced vehicle design, and targeted user training to mitigate risks associated with the growing adoption of micro-mobility solutions in urban areas.

Reference

Naude, C., Riahi, E., Canu, B., Herbin, L., Vincent, F., Serre, T., 2023. Braking and acceleration capabilities of e-bicycles, e-scooters and e-monowheels. 31th Annual Congress of the European Association for Accident Research EVU, 05-07 Oct 2023. Limasol, Cyprus