ITE Journal – December 2019 - 32

Table 1. Number of injury crashes at studied intersections before and after
the RLC program.
Number of Crashes
Crash type
(annual)

Before
Installing
Camera

After
Installing
Camera

Change
(percent)

Total Crashes

1777

1557

-12.4

Total Crashes
All studied
Excluding
intersections Rear-End

1496

1142

-23.7

Rear-End
Crashes

281

415

47.7

Total Crashes

1228

1063

-13.4

1038

767

-26.1

190

296

55.8

Intersection
Type

Total Crashes
Studied
intersections Excluding
with camera Rear-End
Rear-End
Crashes
Figure 1. The RLC distribution across Chicago intersections in 2010.
adaption period. The crash dataset consists of the aggregated yearly
injury crashes frequencies that occurred at intersections before and
after RLC installation (consisting of intersections with cameras
[90 sites] and without cameras [60 sites]). The preliminary analysis
of crash data shows that the average annual number of crashes
during 2005-2007 was 12 percent higher than the time period after
installing the RLC (2010-2012). Respectively, the crash frequency,
excluding rear-end crashes, dropped by about 24 percent. On the
other hand, a (raw) 47 percent increase in rear-end crashes was
observed after the RLC program (Table 1.)

Land Use
It is shown that drivers take more risk while driving under the
influence,31,32 which can be associated with a higher number
of RLRs. We tested this hypothesis by examining the potential
relationship between the distribution of land-use activities that
serve alcohol and intersections crash frequency. To this end, the
major points of interest (POIs) in Chicago were collected using the
Open Street Map POI dataset and incorporated into analyses in the
form of number of POIs in 500 meter (m) (1,640 feet [ft.]), 700 m
(2,297 ft.), and 1,000 m-buffer (3,281 ft.) around the intersections.

RLC Distribution
The spillover effect of RLCs was examined in the model as spatially
weighted variables. To this end, the network distance matrix of
32

D ecem ber 2019

i t e jo u rn al

Chicago intersections was extracted from the Google API service.
In addition to testing the linear spillover effect of RLCs, the
potential nonlinear effects were examined using inverse spatial
weights and squared inverse spatial weights.

Intersection Characteristics
The intersection function was defined in terms of the average
annual daily traffic (AADT) passing through the intersection
and the speed limit of the intersection approaches. Given that the
turning movements at intersections increase the conflicts and risk
of crashes, we examined the safety impacts of the right-turn on
red (after stop) and the availability of left lanes at the intersection.
The intersections geometry including the number of lanes and the
median type was considered as potential risk factors. We distinguished between major and minor approaches function, control,
and geometry characteristics to better capture the potential impacts
of risk factors. Table 2 summarizes the statistics of the intersection
variables used for developing the model.

Model Results
The model was developed using a panel dataset containing the
annual injury crash frequency in two time periods (2005-2007
and 2010-2012), while annual injury crash frequency, the presence
of the RLC at intersections and some intersections characteristics variate over time. The dataset was split into two subsets for
modeling purposes, testing and training data. The testing and
training data were sampled randomly, where the test and training



ITE Journal – December 2019

Table of Contents for the Digital Edition of ITE Journal – December 2019

President’s Message
Director’s Message
People in the Profession
ITE News
10th Annual ITE Collegiate Traffic Bowl Grand Championship Tournament Recap
Board Committee: Women of ITE: Allies in Design and in the Workplace
Member to Member: Ariel Farnsworth (M)
Calendar
Where in the World?
Industry News
ITE 2019 Year in Review
Impacts of Red-Light Cameras on Intersection Safety: A Bayesian Hierarchical Spatial Model
Dynamic Flashing Yellow Arrow Operations
Advisory Bike Lanes and Shoulders: Current Status and Future Possibilities
Professional Services Directory
ITE Journal – December 2019 - 1
ITE Journal – December 2019 - 2
ITE Journal – December 2019 - 3
ITE Journal – December 2019 - President’s Message
ITE Journal – December 2019 - 5
ITE Journal – December 2019 - Director’s Message
ITE Journal – December 2019 - 7
ITE Journal – December 2019 - People in the Profession
ITE Journal – December 2019 - ITE News
ITE Journal – December 2019 - 10
ITE Journal – December 2019 - 11
ITE Journal – December 2019 - 12
ITE Journal – December 2019 - 13
ITE Journal – December 2019 - 10th Annual ITE Collegiate Traffic Bowl Grand Championship Tournament Recap
ITE Journal – December 2019 - 15
ITE Journal – December 2019 - 16
ITE Journal – December 2019 - Board Committee: Women of ITE: Allies in Design and in the Workplace
ITE Journal – December 2019 - 18
ITE Journal – December 2019 - 19
ITE Journal – December 2019 - Member to Member: Ariel Farnsworth (M)
ITE Journal – December 2019 - Where in the World?
ITE Journal – December 2019 - Industry News
ITE Journal – December 2019 - ITE 2019 Year in Review
ITE Journal – December 2019 - 24
ITE Journal – December 2019 - 25
ITE Journal – December 2019 - 26
ITE Journal – December 2019 - 27
ITE Journal – December 2019 - 28
ITE Journal – December 2019 - Impacts of Red-Light Cameras on Intersection Safety: A Bayesian Hierarchical Spatial Model
ITE Journal – December 2019 - 30
ITE Journal – December 2019 - 31
ITE Journal – December 2019 - 32
ITE Journal – December 2019 - 33
ITE Journal – December 2019 - 34
ITE Journal – December 2019 - 35
ITE Journal – December 2019 - 36
ITE Journal – December 2019 - Dynamic Flashing Yellow Arrow Operations
ITE Journal – December 2019 - 38
ITE Journal – December 2019 - 39
ITE Journal – December 2019 - 40
ITE Journal – December 2019 - 41
ITE Journal – December 2019 - 42
ITE Journal – December 2019 - 43
ITE Journal – December 2019 - Advisory Bike Lanes and Shoulders: Current Status and Future Possibilities
ITE Journal – December 2019 - 45
ITE Journal – December 2019 - 46
ITE Journal – December 2019 - 47
ITE Journal – December 2019 - 48
ITE Journal – December 2019 - 49
ITE Journal – December 2019 - Professional Services Directory
ITE Journal – December 2019 - 51
ITE Journal – December 2019 - 52
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