1. Exploring Traffic Danger
for Bicyclists
Initial Findings from a Recent Survey of Drivers
and Bicyclists in the Bay Area
Rebecca Sanders, UC Berkeley
Pro Walk Pro Bike
September 11, 2012

2. Overview
• Survey on perceived and actual bicycle danger
• Findings: Detecting trends
– Cyclist groups worry about different safety issues
– Frequent cyclists’ worries related to near misses and
actual collisions for self, friends, and family
– Infrequent cyclists slightly affected by personal
experiences and those of friends and family
– Potential cyclists slightly affected by experiences of
friends and family
– Near misses need more attention
– Support for bicycling associated with worries about
cycling
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3. Methodology & Study Area
• Internet survey
• Convenience sample
• 467 respondents
(42% response rate)
• Surveyed summer, 2011 2
30
7
95
74
226
14
3
Image credit: Bay Area Air Quality Management District 3

4. Survey Population
Age Range and Sex Comparison of Survey and Bay Area Populations
Total (N=467) *Bay Area (N=4,496,326)
Age Range % %
18-24 6 9
25-34 36 15
35-44 18 15
45-54 21 15
55-64 16 12
65+ 4 12
Sex
Male 45 49
Female 54 51
Source: U.S. Census Summary File 1, Table QT-P1 Age Groups and Sex 4

5. Survey Population
Survey Respondents by Age and Cycling Frequency
Infrequent Frequent
Non-cyclists cyclists cyclists
Age (n=194) (n=171) (n=102)
Range % % %
18-24 4 5 10
25-34 34 35 41
35-44 18 18 17
45-54 16 29 16
55-64 21 11 16
65+ 7 2 -
Chi-square significant p < 0.10 5

6. Survey Population
Survey Respondents by Sex and Cycling Frequency
Infrequent Frequent
Non-cyclists cyclists cyclists
(n=194) (n=171) (n=102)
Sex % % %
Male 33 56 48
Female 64 43 51
Chi-square significant p < 0.000
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7. Survey Population
Race and Ethnicity Comparison of Survey and Bay Area Populations
Total *Bay Area
(N=467) (N=4,496,326)
Race/Ethnicity % %
Caucasian/White 59 50
Asian 15 23
African American/Black 5 9
Hispanic 5 22
Native American/Alaska Native - 1
Native Hawaiian/Pacific Islander 1 1
Other 7 10
Two or more races 4 6
Source: U.S. Census Summary File 1, Table QT-P3 Race and Hispanic or Latino Origin
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8. Survey Population
Survey Respondents by Race/Ethnicity and Cycling Frequency
Non- Infrequent Frequent
cyclists cyclists cyclists
(n=194) (n=171) (n=102)
Race/Ethnicity % % %
Caucasian/White 53 61 69
Asian 19 13 10
African American/Black 7 4 3
Hispanic 5 5 5
Native American/Alaska Native 1 - -
Native Hawaiian/Pacific Islander 1 2 1
Other* 8 8 6
Two or more races 5 5 4
*Other included Indian and Middle Eastern
Chi-square significant p < 0.10
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9. Survey Population
Income Comparison of Survey and Bay Area Populations
Total *Bay Area
(N=467) (N=4,496,326)
Annual HH Income % %
< $35k 15 22
$35k-$49k 10 11
$50k-$74k 19 16
$75k-$99k 13 13
$100k-$149k 18 18
$150k + 12 19
Source: 2010 American Community Survey, 5-Year Estimates, Table S-1901 Income in the Past 12 Months
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10. Survey Population
Survey Respondents by Income and Cycling Frequency
Infrequent Frequent
Non-cyclists cyclists cyclists
Annual HH (n=194) (n=171) (n=102)
Income % % %
< $35k 15 12 17
$35k-$49k 12 9 8
$50k-$74k 19 19 20
$75k-$99k 13 13 13
$100k-$149k 14 22 20
$150k + 11 13 12
Chi-square not significant
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11. Survey Results
Percentage of Respondents who Feel Safe Traveling on Different Street Types
Infrequent Frequent
Non-cyclists cyclists cyclists Total
(n=193) (n=171) (n=102) (N=466)
% % % %
Residential
Bicycle* 71 78 83 76
Drive 89 91 89 90
Walk 89 95 96 93
Commercial
Bicycle 29 23 32 28
Drive 73 74 67 72
Walk* 76 81 85 80
* Significant difference at level of p < 0.10
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12. Survey Results
Percentage of Respondents who Feel Safe Traveling on Different Street Types
Infrequent Frequent
Non-cyclists cyclists cyclists Total
(n=193) (n=171) (n=102) (N=466)
% % % %
Residential
Bicycle* 71 78 83 76
Drive 89 91 89 90
Walk 89 95 96 93
Commercial
Bicycle 29 23 32 28
Drive 73 74 67 72
Walk* 76 81 85 80
* Significant difference at level of p < 0.10
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13. Survey Results
Percentage of Respondents who Feel Safe Traveling on Different Street Types
Infrequent Frequent
Non-cyclists cyclists cyclists Total
(n=193) (n=171) (n=102) (N=466)
% % % %
Residential
Bicycle* 71 78 83 76
Drive 89 91 89 90
Walk 89 95 96 93
Commercial
Bicycle 29 23 32 28
Drive 73 74 67 72
Walk* 76 81 85 80
* Significant difference at level of p < 0.10
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14. Survey Results
The Extent to which Safety Concerns “Strongly Influence” Potential
and Infrequent Cyclists, and “Always Worry” Frequent Cyclists
40%
30%
20%
10%
0%
I'll be hit by an Drivers will drive Drivers will drive I'll be cut off while I'll make a mistake I'll be hit by a car Drivers will be
inattentive driver too fast near me too close to me turning and hurt myself or door aggressive toward
others me
Potential Cyclists (n=148) Infrequent Cyclists (n=168) Frequent Cyclists (n=94)
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15. Survey Results
The Extent to which Safety Concerns “Strongly Influence” Potential
and Infrequent Cyclists, and “Always Worry” Frequent Cyclists
40%
30%
20%
10%
0%
I'll be hit by an Drivers will drive Drivers will drive I'll be cut off while I'll make a mistake I'll be hit by a car Drivers will be
inattentive driver too fast near me too close to me turning and hurt myself or door aggressive toward
others me
Potential Cyclists (n=148) Infrequent Cyclists (n=168) Frequent Cyclists (n=94)
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16. Survey Results
The Extent to which Safety Concerns Have “Some Influence” on Potential
and Infrequent Cyclists, and “Sometimes Worry” Frequent Cyclists
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
I'll be hit by an Drivers will drive Drivers will drive I'll be cut off while I'll make a mistake I'll be hit by a car Drivers will be
inattentive driver too fast near me too close to me turning and hurt myself or door aggressive toward
others me
Potential Cyclists (n=148) Infrequent Cyclists (n=168) Frequent Cyclists (n=94) 16

17. Survey Results
Potentially Dangerous Incidents for Bicyclists – Bicyclists’ Self Report (n=273)
Incident Incidence
Cyclist was passed with fewer than 3 feet 65%
Driver blocked bike lane while waiting for someone or parking 54%
Driver/passenger opened car door and hit / almost hit cyclist 45%
Driver hit / almost hit cyclist while turning 41%
Driver honked / yelled at cyclist when s/he was not in the
42%
wrong
Driver merged into lane and hit / almost hit cyclist 31%
Driver drove aggressively around cyclist 42%
Driver tried to beat cyclist to a turn and hit / almost hit him/her 23%
Driver blocked cyclist from merging into lane after cyclist
25%
signaled

18. Survey Results
Potentially Dangerous Incidents for Bicyclists – Bicyclists’ Self Report (n=273)
Actually
Incident Incidence
hit?
Cyclist was passed with fewer than 3 feet 65% 2%
Driver blocked bike lane while waiting for someone or parking 54% 2%
Driver/passenger opened car door and hit / almost hit cyclist 45% 6%
Driver hit / almost hit cyclist while turning 41% 8%
Driver honked / yelled at cyclist when s/he was not in the
42% 2%
wrong
Driver merged into lane and hit / almost hit cyclist 31% 4%
Driver drove aggressively around cyclist 42% 2%
Driver tried to beat cyclist to a turn and hit / almost hit him/her 23% 3%
Driver blocked cyclist from merging into lane after cyclist
25% 1%
signaled

19. Survey Results
Potentially Dangerous Incidents for Bicyclists – Bicyclists’ Self Report (n=273)
Actually Incident :
Incident Incidence
hit? Hit
Cyclist was passed with fewer than 3 feet 65% 2% 29
Driver blocked bike lane while waiting for someone or parking 54% 2% 37
Driver/passenger opened car door and hit / almost hit cyclist 45% 6% 8
Driver hit / almost hit cyclist while turning 41% 8% 5
Driver honked / yelled at cyclist when s/he was not in the
42% 2% 23
wrong
Driver merged into lane and hit / almost hit cyclist 31% 4% 8
Driver drove aggressively around cyclist 42% 2% 23
Driver tried to beat cyclist to a turn and hit / almost hit him/her 23% 3% 8
Driver blocked cyclist from merging into lane after cyclist
25% 1% 34
signaled

20. Survey Results
Influence of Collision and Near Miss Experiences on Worries about Safety
Related Collision Related Near Miss
Potential Infrequent Frequent Potential Infrequent Frequent
cyclist cyclist cyclist cyclist cyclist cyclist
(n=145) (n=164) (n=93) (n=145) (n=164) (n=93)
Worry about being cut
off by a turning driver
n/a * * n/a - ***
Worry about being
doored
n/a - * n/a - ***
Worry about drivers
passing too close
n/a - - n/a - *
Worry about aggressive
drivers
n/a - - n/a - ***
Significance indicated at the following levels: * p ≤ 0.10; ** p ≤ 0.01; *** p ≤ 0.001

21. Survey Results
Influence of the Experiences of Friends and Family on Worries about Safety
You, friends, or family have
You, friends, or family have
crashed with a driver while
crashed with a cyclist while driving
bicycling
Potential Infrequent Frequent Potential Infrequent Frequent
cyclist cyclist cyclist cyclist cyclist cyclist
(n=145) (n=164) (n=93) (n=145) (n=164) (n=93)
Worry about being cut
off by a turning driver - - * - - **
Worry about being
doored * - - * - *
Worry about drivers
passing too close - - - - * -
Worry about making a
mistake - - * - - *
Significance indicated at the following levels: * p ≤ 0.10; ** p ≤ 0.01; *** p ≤ 0.001

22. Survey Results
Significant correlation (p < 0.10) between support for bicycling
in one’s city and the following worries about safety:
1. Worry about being hit by a car door
2. Worry about aggressive driving
3. Worry about drivers passing too close
4. Worry about making a mistake that could hurt oneself or
others
5. Worry about losing one’s balance

23. Limitations & Future Research
• Systematic sample
• Internet/email population not representative
• Potential self-selection bias
• Trip Diary
• Count “near misses” and hits
• Recall bias
• Revised survey
• Uniform scales
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24. Conclusions
• Frequent cyclists consistently affected by personal
experiences and those of friends and family
• Infrequent cyclists slightly affected by personal
experiences and those of friends and family
• Potential cyclists
– Slightly affected by experiences of friends and family
– Worried about different occurrences than frequent cyclists
– More worried than frequent cyclists about most encounters
• Near misses influential and pervasive
• Significant relationship between worries about safety
and support for bicycling
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25. Next Steps
• Detailed crash analysis of Bay Area
• Exploration of attitudes, behaviors, and knowledge of
roadway laws and their relationship to
• Perceived safety
• Roadway design preferences
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26. Thank you!
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