Schedule

1
Schedule
2
Deliverables

• Methodology for cost-benefit-risk tradeoff
  analysis
• Evaluation of literature
• Characterization of experience of resident
  engineers
• Recommendations of factors and measurement
  endpoints
• Identification of options for site selection and
  upgrading, including the two phases of screening
  and evaluation

3
Deliverables (cont.)

• Databases and demonstration of the above
  methodology
• Documentation of the automating spreadsheets
• Interim and final reports, presentations, and
  automating spreadsheets
• Maintenance of an internet web site

4
Review of Comparison Tool
5
Motivation

• Tools are needed to equitably balance
• Crash reduction,
• Capacity improvement, and
• Project cost
• Other factors
• To aid in the decisions of what roadway-projects
  to undertake with available funds

6
Project Objective

• Our objective is to provide tools to assist the
  Virginia Department of Transportation in
  improving the comparison in planning of potential
  roadway improvement projects.

7
Criteria Included in Comparison
Explicitly Quantified
Implicitly Addressed
Performance
Aesthetic Value
Environmental Concerns
Cost
Economic Development
Safety
8
Comparison-Tool Options
Crashes per Year Crashes per Vehicle Crashes
Avoided per Vehicle Crashes Avoided per
Year Lives Lost, Injuries
Right of Way Preliminary Engineering Construction
Engineering Life Cycle Length of Road-Section
COST
RISK
Daily Traffic Travel Time Saved per Vehicle Total
Travel Time Saved
PERFORMANCE
9
Intuitive Graphical Representation
Crash risk reduction
Performance gain
Note Icon area is proportional to project Cost.
10
Precision of the Assessment
11
Performance Gain
Cost
Crash Risk Reduction
12
Sample of Database of Richmond District (from
Travis Bridewell)
13
Database of Richmond District
14
Literature Review

• Guiding principles King (1995)
• Prioritization technique Pigman and Agent
  (1991), Caldwell and Wilson (1999)
• Cost-effectiveness approaches
• AASHTO Roadside Design Guide (1989)
• Mak (1995)
• Glennon (1974)

15
Literature Review (cont.)

• Warranting Methods
• Charts
• Flow charts
• Guidance tables and figures
• Experiences of traffic agencies
• New York
• Ohio
• California
• Survey of State DOTs

• Minnesota
• Wyoming
• Alaska

16
Guiding Principles

• (1) Remove hazard
• (2) Relocate hazard
• Lower probability of a collision
• (3) Make the hazard forgiving
• Crash cushions
• Breakaway
• Use guardrail only when all other options
  eliminated
• Alert motorist to any hazard, i.e. flashing
  lights, warning signs, rumble strips, etc.

King (1995)
(From Travis Bridewell)
17
Prioritization Technique

• Procedure used to identify and rank locations for
  guardrail installation and replacement
• Uses a hazard-index point system

Pigman and Agent (1991)
18
Pigman and Agent (1991)
1. Development of critical numbers and rates of
run-off-road accidents
2. Preparation of list of locations with critical
rate of run-off-road accidents
3. Development of hazard-index point system
4. Conduction of a field study
5. Tabulation of hazard-index points
6. Determination of improvement costs
7. Determine improvement benefits
8. Analysis of cost-effectiveness
19
Steps of Technique

• (1) Development of critical numbers and rates of
  run-off-road accidents
• Ac critical accident rate Aa average
  accident rate K constant related to level of
  statistical significance selected (K2.576 for a
  probability of 0.995) M exposure (for
  sections, M was in terms of 100 million
  vehicle-miles, for spots, M was in terms of
  million vehicles

Pigman and Agent (1991)
20
Steps of Technique

• (2) Preparation of list of locations with
  critical rate of run-off-road accidents (i.e.
  list of locations with critical rate factors
  greater than 1.0)
• (3) Development of hazard-index point system

Pigman and Agent (1991)
21
Hazard-Index Point System

• 1. Number of run-off-road accidents 15
• 2. Run-off-road accident rate 15
• 3. Traffic volume 10
• 4. Speed limit or prevailing speed 10
• 5. Lane and shoulder width 10
• 6. Roadside recovery distance 10
• 7. Embankment slope 10
• 8. Embankment height 10
• 9. Culvert presence 5
• 10. Subjective roadside hazard rating 5

Pigman and Agent (1991)
22
Step of Technique (cont.)

• (4) Conduction of a field study
• Data collection on locations with critical rate
  factors greater than 1.0
• (5) Tabulation of hazard-index points
• Develop a list of locations in decreasing order
  in order to identify a manageable number of
  locations on which a cost-effectiveness analysis
  can be performed

Pigman and Agent (1991)
23
Step of Technique (cont.)

• (6) Determination of improvement costs
• (7) Determine improvement benefits
• Accident reduction factors
• Severity indices

Pigman and Agent (1991)
24
Step of Technique (cont.)

• (8) Analysis of cost-effectiveness
• Listing of locations in decreasing benefit-cost
• Optimization of budget

Pigman and Agent (1991)
25
Inputs for Budget Optimization

• Number of locations to be analyzed
• Budget levels to be considered
• Costs assigned to each accident severity
• Interest rate
• Traffic growth rate
• Accident history
• Alternatives for reducing accidents
• Expected improvement life
• Improvement cost
• Annual maintenance cost
• Expected reductions in accidents due to
  improvements

Pigman and Agent (1991)