The Overtaking of Bicyclists
The overtaking behaviour of motorized vehicles in cyclists with and without a child on the same bicycle in the Brussels Capital Region
First author: Toon Ampe Co-authors: prof. dr. Bas de Geus, dr. Ian Walker, dr. Ben Serrien Safe Overtaking Manoeuvre
Road Safety Advisory Council (Australia) Unsafe Overtaking Manoeuvre Introduction
Safe overtaking manoeuvre
perceived traffic risk
cycling prevalence (1-3)
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 4
(1-3) see last slides Introduction
Lateral clearance distance
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 5 Introduction
Larger lateral clearance distance Smaller lateral clearance distance
The motorized Professional drivers / Larger vehicles vehicle (3-7) Opposing traffic
Tangent section The road Curved sections Wider roads Centreline environment (6-10) On-road cycling lanes
Higher speed Closer to the edge (road and cycling lane) Being female The cyclist (4-6, 11-13) Helmet wearing ‘Police’ vest
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 6 (3-7)(6-10)(4-6, 11-13) see last slides Introduction
Aim of the study
- Lateral clearance distance
- 3 cycling conditions:
Cyclist without child
Cyclist with child bike seat
Cyclist with child bike trailer
- Safest means of transport
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 7 Methods
Measurements
- Instrumented bicycle (distance sensor) - 17 cycling trips - Regular commuter/utility cyclist
Road
- One single, flat, bidirectional road - Two types of cycling infrastructure - Brussels Capital Region
Cycling conditions
- 3 different conditions
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 8 Methods
-23 cm Sensor
- Ultrasonic distance sensor
• accuracy: ± 1 cm • frequency: 10 measurements per second
- Mounted on luggage rack
• Substraction for outermost point
- Bicycle handlebar -45 cm
- Child bike trailer
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 9 Main finding 1
• 1417 overtaking manoeuvres Mean = 124.2 Std. Dev. = 38.3
• Mean lateral clearance distance = 124.2 cm 25.4% 74.6%
• Significantly > 100 cm
• 25.4% < 100 cm
• Safety problem!
Punishment? 100
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 10 Main finding 2
• Cyclists without child = 117.3 cm *
• Cyclists with child = 127.5 cm
• Larger and safer with child
• Drivers’ perception (13)
• Overtaking manoeuvre = adjustable (13)
Without child With child
* Significant at p ≤ 0.05
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 11 Main finding 3 Without child Child bike seat Child bike trailer
• Lateral clearance distance * * * * * ≈ cycling condition ≈ peak traffic hours
• Off peak traffic hours
- Child bike trailer = safer than without
• Morning & evening peak traffic hours
- Child bike seat = safest
* Significant at p ≤ 0.05
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 12 Conclusion
• Larger lateral clearance distances when a child is present
• Safest way of child transport dependent of
• peak traffic hours
• Child bike seat safest during peak hours
• Illegal overtaking manoeuvres occur in every category
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 13 Conclusion
• Specific study area (11)
• Generalising of the results?
• Other regions, cities and/or countries
• Speed and type of the motorized vehicle
Introduction Methods Main finding 1 Main finding 2 Main finding 3 Conclusion
31/10/2019 - 14 Thank you for your attention
[email protected] References
• 1. Sanders RL. Perceived traffic risk for cyclists: The impact of near miss and collision experiences. Accid Anal Prev. 2015; • 2. Mueller N, Rojas-Rueda D, Cole-Hunter T, de Nazelle A, Dons E, Gerike R, et al. Health impact assessment of active transportation: A systematic review. Vol. 76, Preventive Medicine. 2015. p. 103–14. • 3. Dozza M, Schindler R, Bianchi-Piccinini G, Karlsson J. How do drivers overtake cyclists? Accid Anal Prev. 2016;88:29–38. • 4. Walker I. Drivers overtaking bicyclists: Objective data on the effects of riding position, helmet use, vehicle type and apparent gender. Accid Anal Prev. 2007;39(2):417–25. • 5. Chapman JR, Noyce DA. Influence of roadway geometric elements on driver behavior when overtaking bicycles on rural roads. J Traffic Transp Eng (English Ed. 2014;1(1):28–38. References
• 6. Kay JJ, Savolainen PT, Gates TJ, Datta TK. Driver behavior during bicycle passing maneuvers in response to a Share the Road sign treatment. Accid Anal Prev. 2014;70:92–9. • 7. Llorca C, Angel-Domenech A, Agustin-Gomez F, Garcia A. Motor vehicles overtaking cyclists on two-lane rural roads: Analysis on speed and lateral clearance. Saf Sci. 2017;92:302–10. • 8. Shackel SC, Parkin J. Influence of road markings, lane widths and driver behaviour on proximity and speed of vehicles overtaking cyclists. Accid Anal Prev. 2014;73:100–8. • 9. Mchale A, Stewart K. Cycle lanes: their effect on driver passing distance in urban areas. Transport. 2014;2–7. References
• 10. Chapman J, Noyce D. Observations of Driver Behavior During Overtaking of Bicycles on Rural Roads. Transp Res Rec J Transp Res Board [Internet]. 2012;2321:38–45. Available from: http://trrjournalonline.trb.org/doi/10.3141/2321-06 • 11. Olivier J, Walter SR. Bicycle Helmet Wearing Is Not Associated with Close Motor Vehicle Passing: A Re-Analysis of Walker, 2007. PLoS One. 2013;8(9). • 12. Walker I, Robinson DL. Bicycle helmet wearing is associated with closer overtaking by drivers: A response to Olivier and Walter, 2013. Accid Anal Prev. 2019; • 13. Walker I, Garrard I, Jowitt F. The influence of a bicycle commuter’s appearance on drivers’ overtaking proximities: An on-road test of bicyclist stereotypes, high-visibility clothing and safety aids in the United Kingdom. Accid Anal Prev. 2014;64:69–77. Q&A – Sensor Q&A - Data Analysis
Statistical analyses using R • Checking for random effects (cluster sampling) -> session = significant • Further tests corrected for session • Multi model influencing • Combination of 3 models to form 95% confidence set • Distance ~ cycling condition * peak traffic hours • Distance ~ cycling condition + peak traffic hours + infrastructure • Distance ~ cycling condition + peak traffic hours • Mixed effects regression Q&A - Data Analysis
A priori analysis with G*Power 3.0.10
• Small effect size (f=0.10)
• Significance level α=0.05
• Power of 1-β=0.80
Number of overtaking manoeuvres = 1290 Q&A - Study Area
Brussels Capital Region
- extensive public transport network - dense, very congested network of urban motorways - network of various different cycling infrastructures
Commuting Trips 2005 2014
Car 45.1 % 37,9 %
Public Transport 47.2 % 53.1 %
Bicycle 1.2 % 3.0 % Q&A – Descriptives
Peak traffic hours Cycling infrastructure Cycling condition MEAN SD MIN Q1 MEDIAN Q3 MAX N_obs Off-peak Shared lane marking Without child 126,8 36,1 46,0 102,8 127,0 153,5 233,0 100 Child bike seat 129,7 31,7 48,0 111,5 131,0 144,0 217,0 100 Child bike trailer 136,4 29,6 82,0 113,3 137,0 154,8 221,0 82 Bike lane Without child 120,2 35,0 49,0 95,0 121,0 140,0 318,0 119 Child bike seat 129,8 36,9 42,0 107,0 130,0 153,0 230,0 97 Child bike trailer 134,0 36,9 40,0 108,0 134,0 154,0 243,0 81 Morning peak Shared lane marking Without child 97,3 44,9 50,0 71,0 87,0 108,0 304,0 45 Child bike seat 122,7 46,0 45,0 93,3 124,5 139,3 303,0 38 Child bike trailer 106,8 25,4 65,0 91,0 105,0 123,0 157,0 13 Bike lane Without child 97,4 30,6 47,0 71,5 97,0 120,5 159,0 35 Child bike seat 124,1 32,6 67,0 100,5 122,5 137,3 222,0 28 Child bike trailer 129,3 39,7 61,0 107,0 123,0 138,0 213,0 13 Evening peak Shared lane marking Without child 120,5 37,5 60,0 97,0 119,0 137,0 290,0 93 Child bike seat 137,0 53,7 40,0 109,5 127,0 153,5 317,0 83 Child bike trailer 123,0 34,4 27,0 102,0 122,0 142,0 268,0 121 Bike lane Without child 117,4 35,0 59,0 95,5 117,0 133,3 282,0 64 Child bike seat 123,0 41,8 21,0 95,0 121,0 145,0 314,0 113 Child bike trailer 122,9 36,3 8,0 102,5 124,0 144,3 214,0 192 Q&A Cycling condition
Mean lateral clearance distance ○ Significant difference ○ Without child < Bike seat ○ Without child < Bike trailer ○ Bike seat = Bike trailer
Illegal manoeuvres ○ Without child = 34.6% ○ Bike seat = 21.2% ○ Bike trailer = 20.6% Q&A Cycling Infrastructure and Traffic
Mean lateral clearance distance ● Cycling Infrastructure ○ Insignificant difference ○ Shared lane marking = 125.5 cm ○ Bike lane = 123.1 cm ● Peak Traffic Hours ○ Significant difference ○ Off > Morning ○ Evening > Morning