Evaluation of Illinois Highway Safety Programs: Six Years
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Transcript Evaluation of Illinois Highway Safety Programs: Six Years
Kim Kolody Silverman, PE
CH2M HILL representing
Illinois Department of Transportation
We commonly trade safety off against
something else
Environment
Safety
HSM Tools
Safety
Impacts
• Traffic Noise
Model 1.0
• CAL3QHC
• Mobile 5a
• 3-D Visualization
• CITYGREEN
Environmental
Impacts
•
•
•
•
•
•Construction
HCM
Plans
CORSIM
•Cost Models
PASSER
TRANSYT7F •Real estate
appraisals
VISSIM
•DOT databases
Traffic
Operations
Right-of-Way
Greater weight
More quantitative
Design
Criteria
(nominal
safety)
Costs
We’re Interested in Other Impacts for Project Level Decisions – What
3
About Substantive Safety?
Part A
Introduction
Human Factors
Fundamentals
Part B
Roadway Safety
Management
Process
Part D
Crash Modification
Factors (CMFs)
Part C
Predictive Method
Tools for Implementing HSM
Excel Spreadsheets
Interactive Highway Safety Design Model
(IHSDM)
Safety Analyst
HSM Excel
Spreadsheets
Project level basis
Simple, straightforward
Limited data required
Worksheet 3A -- Predicted and Observed Crashes by Severity and Site Type Using the Site-Specific EB Method
(1)
Site type
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Observed Overdispersion
Weighted
Expected
crashes,
Parameter, k
adjustment, w
average crash
Nobserved
frequency,
(crashes/year)
Nexpected
Predicted average crash frequency
(crashes/year)
N predicted
N predicted
N predicted
Equation A-5 from Equation A-4
(TOTAL)
(FI)
(PDO)
Part C Appendix
from Part C
Appendix
ROADWAY SEGMENTS
Segment 1
6.106
1.960
4.146
10
0.157
0.510
8.0
Segment 2
0.495
0.159
0.336
2
2.360
0.461
1.3
1.000
0.0
0.394
2.9
1.000
0.0
1.000
0.0
--
12.3
Segment 3
INTERSECTIONS
Intersection 1
Intersection 2
2.847
1.181
1.665
3
0.540
Intersection 3
COMBINED (sum of column)
9.448
3.300
6.147
15
--
Interactive Highway
Safety Design Model
Provides expected safety,
operational performance
HSM techniques +
Modules to compare design
to standards
Requires detailed data input
Free
The Vision of SafetyAnalyst –
Software Akin to the HCS+
1
2
3
Definitive; represents
quantitative ‘state-ofthe-art’ information
Widely accepted within
professional practice of
transportation
engineering
Science-based; updated
regularly to reflect
research
Purpose of SafetyAnalyst
SafetyAnalyst provides state-of-the-art tools
for safety management that provide
capabilities beyond those currently
available to highway agencies
Effectiveness of decision making
Efficiency of decision support
Intended for those who will:
Identify candidate sites for safety improvements
Investigate the types of safety improvements
needed for specific sites
Assess whether specific safety improvements are
economically justified and should be
programmed
Evaluate the safety effectiveness of implemented
projects
Road Safety Management
Process
Network Screening
Diagnosis & Countermeasure Selection
Economic Appraisal & Prioritization
Safety Effectiveness Evaluation
Module 1
Network Screening
Network Screening
Review highway network (or any portion of
the network) to identify sites with potential
for safety improvement
Identify sites that are candidates for further
investigation
6 different methods for screening
Module 2
Diagnosis & Countermeasure Selection
Helps to identify accident patterns of interest at
specific sites
Guides user in the diagnosis of safety problems at
specific sites
Suggests countermeasures that address identified
accident patterns of interest
Lets user select appropriate countermeasures
Module 3
Economic Appraisal & Prioritization
Perform economic analysis of alternative
countermeasures for a specific site
Perform economic analysis of countermeasures
across selected sites
Select mix of sites and countermeasures to
maximize benefits within a given budget
Develop priority ranking of alternative
improvements
Module 4 – Countermeasure
Evaluation
Safety Effectiveness Evaluation
Conduct before-after evaluations of
implemented countermeasures
Quantify the safety effectiveness of
implemented countermeasures based on:
Percent change in accident frequency
Change in proportion of target accidents
Test Data Input for Illinois
Category
Test Areas
Route Type
Number of roadway segments
Roadway mileage
Number of intersections
Number of crashes
3 Counties
1 Township
State and Local facilities
28,093
7,471
18,704
118,093
Note:
Counties are Champaign, Sagamon, Vermillion and the township is West Chicago
Crashes represent 2005 to 2009 fatal, A-injury, B-injury, C-Injury, and PDO
Data Process for Illinois
3.5 hours for data import
15 minutes for crash data script
2.5 hours for post processing
15 minutes for calibration
Total = 6.5 hours
for approximately 5% of total data set
Challenges
Data input and processing takes some time
Requires user training
Requires agency support
Cost
Challenges
Data Input and Processing
Coordinate multiple data sources, data owners
Determining business rules
Complete data where not available
Data input (SQL vs Oracle)
Data set-up process time
Network screening process time
Benefits
Powerful analysis tool
Automates HSM procedures
Calibrates national default SPFs
Screen large amounts of data
Provides consistent evaluation and results for
decision making
Benefits
Flexible for user
Countermeasures, service life, costs included
Automates various economic comparisons
Set of tools that allows for a better selection
of sites and improved prioritization
techniques for decision making to maximize
resources to reduce severe crashes
Benefits
Forces coordination between divisions of
the agency
Better data
More data
Understanding of data application across the
agency which may influence potential changes
in agency business practices
HSM Implementation Tool:
Recommendations
Use HSM Excel Spreadsheets where appropriate
Apply IHSDM where appropriate
Start preparing Safety Analyst for use
HSM Implementation Tool:
Safety Analyst Recommendations
Determine funding options
Start the process of data identification, mapping
Start educating staff at central office
Engage IT staff
HSM Implementation Tool:
Safety Analyst Recommendations
Start with a small test data set
Good team coordination
Decision making in data set-up
Seek assistance from AASHTO, peers
For more information
Highway Safety Manual
http://www.highwaysafetymanual.org/
Safety Analyst
http://www.safetyanalyst.org/
Interactive Highway Safety Design Model
http://www.tfhrc.gov/safety/ihsdm/ihsdm.htm
Questions
Priscilla Tobias, PE
State Safety Engineer
Illinois Department of
Transportation
(217) 782-3568
[email protected]
Kim Kolody, PE
CH2M HILL
(773) 458.2883
[email protected]
[email protected]