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
priscilla.tobias@illinois.gov
Kim Kolody, PE
CH2M HILL
(773) 458.2883
Kim.Kolody@ch2m.com
kolodyka@illinois.gov