ITE Journal May 2018 - 44

Data Analysis
VPD and encroachment rate were the dependent variables
used to measure changes in the relative safety of bike facilities.
Researchers first analyzed the data using descriptive statistics
such as mean, median, and mode. Two types of regression
modeling, a multivariate OLS regression where the independent
variables are regressed on a continuous VPD dependent variable,
and a logit model where all independent variables are regressed
on the binary Encroachments variable, were used to confirm
descriptive results. Copies of estimated models are available from
the authors.

Results
Data were collected for 2,949 passing events: 1,408 for male riders
and 1,541 for the female rider.

Facility Type
The average VPD was 70 inches, while the median VPD was 68
inches (Table 3). Seventy-two percent of the observations are
between 49 inches and 84 inches or about 4 to 7 feet away from
the cyclist. The average VPD was greatest on the bollard bike lane
(90 inches). VPD was lowest and about the same on no bicycle
facility roads and the standard bike lane, but encroachments were
significantly higher on the 4-lane no facility road.
There were 33 encroachments resulting in a 1.12 percent
encroachment rate for all observations. Sixty-four percent of these
encroachments occurred on the 4-lane no facility road while 15
percent occurred on the bicycle boulevard. The encroachment
rate on the 4-lane no facility road was highest at 5.69 percent. All
other roads had encroachment rates less than, or near 1 percent.
The regression results reinforced the findings that VPD
generally increases as a facility is more protected.

A cyclist is more likely to be encroached upon on a bike
boulevard than any other bike facility.

Vehicle Type
Most passing vehicles were Category 2 vehicles (Table 4). The
smallest vehicles are Category 1 vehicles, and larger vehicles are
in Categories 4 and above. Table 4 reports the raw data for each
vehicle classification. In general, as vehicle size (category) increases,
average VPD decreases. Category 4 and 5 vehicles have the highest
likelihood of encroachment. 3.1 percent of category 4 vehicles and
5.3 percent of category 5 vehicles encroached. Bigger vehicles had a
higher proportion of encroachments.
Regression modeling reinforces these findings by showing that
Passing Distance steadily decreases as passing vehicles become larger.
At the 5 percent level of significance, the odds of getting encroached
upon by the vehicles in the largest categories are 3.45 times greater than
the likelihood in the smallest vehicle categories. The largest vehicle
category passed closer on average than the two smaller categories.

Gender
VPD is smaller for the female rider. She was passed on average three
inches closer than the male riders. Of the 33 encroachments, the
female rider experienced 24 (73 percent) of them. The minimum
observed for male riders is 13 inches and 16 inches for the female
rider. The regression confirmed that the female rider is passed closer
than the male riders. This conforms to Stipancic et al.'s study that
shows that female riders are more likely to be involved in conflicts
at intersections.4

Roadway Characteristics
Excluding facility type, the presence of an adjacent vehicle played
the largest role in reducing the distance between a cyclist and

Table 4. FHWA Vehicle Categories Data Summary

Summary of Passing
Vehicles

Individual Categories
Average Passing
Total Distance
(Inches)
13
89

Category 1 Motorcycle
Category 2 Lightweight
1844
Passenger Car
Category 3 Heavy Duty
984
Passenger Truck
Category 4 Bus
65

72

Combined Regression Categories
Encroachment
Encroachment
% Of Total
Number of
Rate within
Rate within
% of Total
Encroachments
Encroachments
Category
Category
Encroachments
0
0.0%
0.0%
0.9%
51.1%
17
0.9%
51.1%

67

12

1.2%

36.4%

60

2

3.1%

6.1%

Category 5 Truck

38

67

2

5.3%

6.1%

Category 6-12 Cargo
Truck or Semi

5

65

0

0.0%

0.0%

44

May 2018

i te jo urn al

1.2%

36.4%

3.7%

12.1%



Table of Contents for the Digital Edition of ITE Journal May 2018

President’s Message
Director’s Message
People in the Profession
ITE News
ITE, FHWA, and Carmanah Rally to Keep Rectangular Rapid-Flashing Beacons in Our Safety Toolbox
Improving Arterial Roads to Support Public Health: How Can We Do This?
ITE’s Transportation and Health Initiative
Technical Programs Division Spotlight
Industry News
Calendar
Where in the World?
Member to Member: Jing Zhang, AICP, PTP, LEED AP ND
Countermeasures Prove Effective in Reducing Bicycle Collisions
Guidance on Signal Control Strategies for Pedestrians to Improve Walkability
Factors Affecting Vehicle Passing Distance and Encroachments While Overtaking Cyclists
Measuring the Success of Modal Shift: The Impact on Last Mile Connectivity
Professional Services Directory
ITE Journal May 2018 - 1
ITE Journal May 2018 - 2
ITE Journal May 2018 - 3
ITE Journal May 2018 - President’s Message
ITE Journal May 2018 - 5
ITE Journal May 2018 - Director’s Message
ITE Journal May 2018 - 7
ITE Journal May 2018 - People in the Profession
ITE Journal May 2018 - 9
ITE Journal May 2018 - 10
ITE Journal May 2018 - ITE News
ITE Journal May 2018 - ITE, FHWA, and Carmanah Rally to Keep Rectangular Rapid-Flashing Beacons in Our Safety Toolbox
ITE Journal May 2018 - Improving Arterial Roads to Support Public Health: How Can We Do This?
ITE Journal May 2018 - 14
ITE Journal May 2018 - 15
ITE Journal May 2018 - 16
ITE Journal May 2018 - ITE’s Transportation and Health Initiative
ITE Journal May 2018 - 18
ITE Journal May 2018 - Technical Programs Division Spotlight
ITE Journal May 2018 - Industry News
ITE Journal May 2018 - 21
ITE Journal May 2018 - Where in the World?
ITE Journal May 2018 - 23
ITE Journal May 2018 - 24
ITE Journal May 2018 - 25
ITE Journal May 2018 - 26
ITE Journal May 2018 - Member to Member: Jing Zhang, AICP, PTP, LEED AP ND
ITE Journal May 2018 - 28
ITE Journal May 2018 - Countermeasures Prove Effective in Reducing Bicycle Collisions
ITE Journal May 2018 - 30
ITE Journal May 2018 - 31
ITE Journal May 2018 - 32
ITE Journal May 2018 - 33
ITE Journal May 2018 - 34
ITE Journal May 2018 - Guidance on Signal Control Strategies for Pedestrians to Improve Walkability
ITE Journal May 2018 - 36
ITE Journal May 2018 - 37
ITE Journal May 2018 - 38
ITE Journal May 2018 - 39
ITE Journal May 2018 - Factors Affecting Vehicle Passing Distance and Encroachments While Overtaking Cyclists
ITE Journal May 2018 - 41
ITE Journal May 2018 - 42
ITE Journal May 2018 - 43
ITE Journal May 2018 - 44
ITE Journal May 2018 - 45
ITE Journal May 2018 - Measuring the Success of Modal Shift: The Impact on Last Mile Connectivity
ITE Journal May 2018 - 47
ITE Journal May 2018 - 48
ITE Journal May 2018 - 49
ITE Journal May 2018 - Professional Services Directory
ITE Journal May 2018 - 51
ITE Journal May 2018 - 52
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