the safety of electric bicycles · boele-vos, et al, 2015. effect of physical workload on mental...

The safety of electric bicycles

Paul Schepers

10-06-2016

Rijkswaterstaat

2 The safety of electricbicyclesRWS UNCLASS

Content

• Context

• Cycling safety in general

• The safety of electric bicycles

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Introduction

Definition electric bicycle according to European legislation:

- pedal assistance up to 25 km/h

- same traffic rules as for cyclists

Abbreviations:

- Electric Bicycle: EB

- Classic Bicycle: CB

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EB sales in Europe

0

1 000 000

2 000 000

3 000 000

2011 2012 2013 2014 2015

EB sales Europe

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Fishman, E., & Cherry, C. (2016). E-bikes in the Mainstream: Reviewing a Decade of Research. Transport Reviews, 36(1), 72-91.

Fishman, E., & Cherry, C. (2016). E-bikes in the Mainstream: Reviewing a Decade of Research. Transport Reviews, 36(1), 72-91

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Sales share of electric bicycles in the Netherlands (new bicycles)

0

5

10

15

20

25

30

2007 2008 2009 2010 2011 2012 2013 2014 2015

Sale

s s

hare

(%

) of EBs

Source: BOVAG: https://bovag.nl/BovagWebsite/media/BovagMediaFiles/Cijfers/2016/Fietsverkoop-2007-2015.pdf?ext=.pdf

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Use of EBs in the Netherlands

• EB trips are about 50% longer than CB trips; EB users cycle around 50% more km than CB users

• Most km are by the elderly but the average age of EB users is decreasing

KiM, 2015. Mobiliteitsbeeld: http://web.minienm.nl/mob2015/1_7.htmlVan Boggelen, et al., 2013. Feiten over de elektrische fiets (Facts about the electrically assisted bicycle). Fietsberaad, Utrecht.Schepers, P., 2014. Risico's van elektrische fietsen en fietsers. Delft: Rijkswaterstaat.

Distance travelled by EB by age (2014)

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http://web.minienm.nl/mob2015/1_7.html

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Bicycle use (total: CB+EB) under and above 50 years of age (index, 1993=100)

0

50

100

150

200

250

1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013

0 - 49 years

50+

Source: Statistics Netherlands, National Travel Survey

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Cycling safety

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Crash types

1 Source: Cognos-SWOV

2 Source: medical registrations

Bicycle crash type Share serious

injuries2

Share

fatalities1

Crash without motor vehicle:

single-bicycle crash (fall or

obstacle collision), bicycle-

bicycle, bicycle-pedestrian

76% 11%

Bicycle motor vehicle crash

(including bicycle-moped)

24% 89%

Total 100% 100%

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http://www.swov.nl/cognos/cgi-bin/ppdscgi.exe?

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Share of fatalities according to causes of death statistics

0

20

40

60

80

100

120

140

160

180

200

1995 2000 2005 2010 2015

Cycli

st

fata

liti

es

With motor vehicles

Without motor vehicles

Schepers, P., et al (2016). Bicycle fatalities: Trends in crashes with and without motor vehicles in The Netherlands. Transportation Research Part F, In press.

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Share of single-bicycle crashes (requiring hospitalization) in 11 countries having hospital data

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30 35 40 45

Share

of severe

ly

inju

red c

yclists

(%

)

Share of all severely injured traffic casualties (%)

Schepers, P., et al (2014). An international review of the frequency of single-bicycle crashes (SBCs) and their relation to bicycle modal share. Injury prevention, injuryprev-2013.

Papoutsi, S., et al. (2014). E-bike injuries: Experience from an urban emergency department—A retrospective study from Switzerland. Emergency Medicine International, 5.

EB Switzerland: 83% (N=23)

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Single-bicycle crashes are an important problem

• Infrastructure related, about half of all crashes

– Course mistake

– Slippery or poor road surface

• Cyclist related (some 45%)

– Low speeds, primarily while (dis)mounting

– Baggage against the front wheel or in front wheel spokes

– Braking or steering mistakes

• Bicycle malfunction (5%)

• Other (12%) e.g. external forces such as a gust of wind or dog running against the front wheel

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Examples infrastructure

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Safety of EBs and EB users

• Exposure: more kilometres among older people, who are more susceptible to injuries in the event of a crash

• Risk: many hypotheses that have yet to be tested

• General:

– Much of the research on EB safety is from Asia

– EBs are beginning to reach sufficient levels of market penetration for conducting safety research in Europe

Fishman, E., & Cherry, C. (2016). E-bikes in the Mainstream: Reviewing a Decade of Research. Transport Reviews, 36(1), 72-91

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Hypotheses Risk and speed (1)

• EB users are more at risk due to an increased speed

• Netherlands:

– Fietsberaad: average EB speed 1 km/h higher (19 km/h vs 18 km/h)

– An experiment by SWOV suggests the difference is 2 to 4 km/h when comparing EB and CB use for the same user

• Other countries:

– Germany: average EB speed 2 km/h higher

– US, Tennesee: average EB speed 3 km/h higher

Twisk, et al., 2014. Gedrag op elektrische en gewone fietsen vergeleken.Boele-Vos, et al, 2015. Effect of physical workload on mental workload of cyclists and implications for safety of electrically assisted bicycles. ICSC 2016.Van Boggelen, et al., 2013. Feiten over de elektrische fiets (Facts about the electrically assisted bicycle). Fietsberaad, Utrecht.Schleinitz et al., 2014. Pedelec-naturalistic cycling study. Berlin: GDV UdV; 2014.Langford, et al, 2015. Risky riding: naturalistic methods comparing safety behavior from conventional bicycle riders and electric bike riders. Accident Analysis & Prevention, 82, 220-226.

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Hypotheses Risk and speed (2)

• EB users are less at risk because bicycles are unstable at low speeds

– The same experiment by SWOV shows an EB enables elderly to maintain a safe speed while riding uphill

Boele-Vos, et al., 2015. Effect of physical workload on mental workload of cyclists and implications for safety of electrically assisted bicycles. ICSC 2016.

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Hypotheses vehicle related factors

• EB are heavier than CBs and therefore a bit more difficult to handle while (dis)mounting (also depending on where the centre of mass is located)

– EBs weigh 27.5 kg; 9 kg more than average CBs

• Front wheel traction increases the likelihood of front wheel skidding

– Most new EBs have rear wheel traction

Van Boggelen, et al., 2013. Feiten over de elektrische fiets (Facts about the electrically assisted bicycle). Fietsberaad, Utrecht.

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Hypotheses Personal factors

• Compared to CB users, EB users:

– Have a higher BMI: 27 compare to 25 for CB users

– Report more physical complaints

These differences remain significant after controlling for age and gender

• Learning effect: someone who takes up cycling because of the availability of EBs may be relatively untrained / unfit

• Pedal support helps to prevent tiredness during a trip which may also support EB users’ ability to handle higher workload

Schepers, P., 2014. Risico's van elektrische fietsen en fietsers. Delft: Rijkswaterstaat.

Theurel, J., et al., 2012. Physiological and cognitive responses when riding an electrically assisted bicycle versus a classical bicycle. Ergonomics, 55(7), 773-781.

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• Germany, naturalistic study using video and speed sensor data: similar numbers of “Safety Critical Events” among EB and CB users (49 EB users; 31 CB users)

• Tennessee, naturalistic GPS/GIS-based safety study (bike share): EB and CB riders behave very similarly at traffic control devices, violating at about equal rates

Schleinitz et al., 2014. Pedelec-naturalistic cycling study. Berlin: GDV UdV; 2014.

Langford, et a., 2015. Risky riding: naturalistic methods comparing safety behavior from conventional bicycle riders and electric bike riders. Accident Analysis & Prevention, 82, 220-226.

Observational research

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Crash research focused on crash typesVeiligheidNL and SWOV

• Comparison of crash types of EBs and CBs among victims treated at Emergency Departments in the Netherlands (VeiligheidNL)

• Results:

– EB users were more often involved in single-bicycle crashes, especially while mounting and dismounting

– This difference largely disappeared after controlling for age

• In-depth research by a multi-disciplinary team of researchers (SWOV). EB related factors did not play an important role in the prototypical scenario’s found in the study

– Only the high mass and high position of the battery was mentioned for single-bicycle crashes at low speed

Kruijer, et al., 2013. Fietsongevallen in Nederland (Bicycle Crashes in the Netherlands). VeiligheidNL, Amsterdam.

Davidse, et al., 2014. Fietsongevallen van50+’ers. Den Haag: SWOV.

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Crash research focused on crash riskVeiligheidNL, TNS Nipo, Rijkswaterstaat

• The same sample of crash victims treated at the emergency department were combined with a sample of cyclists without recent crash history

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Association between bicycle type and involvement in crashes for which treatment atan ED is needed

• Controlled for: gender, age, and bicycle use

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Association between bicycle type and injury severity (hospitalization required afteran ED treatment)

• Controlled for: gender, age, and bicycle use, and role of health condition in the crash, speed

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Other studies focused on severity

• Germany: comparison of accident data of 30 EB users and 4,514 CB users in 2007-2013 (GIDAS)

Results: injuries did not occur more often or more serious in EB accidents

• Switzerland: police recorded crashes in 2011-2013

Results: EB accidents are more serious than CB accidents; the differences in accident severity are primarily due to age

Otte, et al., 2014. Pedelecs im Unfallgeschehen und Vergleich zu konventionellen nicht motorisierten Zweiraedern. VKU Verkehrsunfall und Fahrzeugtechnik, 52(2).

Scaramuzza, et al. 2015. E-Bikes im Strassenverkehr–Sicherheitsanalyse. Bern: bfu-Beratungsstelle für Unfallverhütung.

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Conclusions

• The availability of the electric bicycle has encouraged cycling (especially) among the elderly leading to increased bicycle use within the most vulnerable group (exposure)

• Use of electric bicycles is associated with an increased risk to be treated at an emergency department due to a crash, but EB crashes do not seem to be more severe than CB crashes

• More research is needed to examine the most likely explanation for risk differences, e.g.

– Experimental research, e.g. to determine to what degree front wheel traction is a problem

– Crash research with better control for vehicle and person factors

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• Examine technical improvements and new safety features:

– A descending saddle for safe and comfortable dismounting (“Sofiets” developed by University of Twente, Roessingh and INDES)

– Steer assist (concept developed by TU Delft)

Recommendations

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http://www.vogelvrijefietser.nl/hetblad/2013-12/artikel/stuurhulp-uit-delfts-fietslab

http://www.roessingh-concern.nl/nieuws/Slim-en-ondersteund-fietsen-met-de-nieuwe-SOFIETS

http://www.vogelvrijefietser.nl/hetblad/2013-12/artikel/stuurhulp-uit-delfts-fietslab

http://www.roessingh-concern.nl/nieuws/Slim-en-ondersteund-fietsen-met-de-nieuwe-SOFIETS

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Questions

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the safety of electric bicycles · boele-vos, et al, 2015. effect of physical workload on mental...

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