on the horizon… future directions in the use of traffic safety data 30 th annual traffic records...
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The State of Traffic Safety… Public Expenditures on Transportation were more than $1.3 Trillion during this periodTRANSCRIPT
On the Horizon…Future Directions in The Use of
Traffic Safety Data
30th Annual Traffic Records Forum | July 27, 2004
Eric DumbaughDoctoral Candidate
School of Civil and Environmental EngineeringGeorgia Institute of Technology
Traffic Fatality Rates
Fatality Rates for U.S. Roadways
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Fatalities Per MillionPopulationFatalities Per MillionVMT
Fatalities on U.S. Roadways
32,000
34,000
36,000
38,000
40,000
42,000
44,000
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
No.
of F
atal
ities
The State of Traffic Safety…
Public Expenditures on Transportation were more than
$1.3 Trillion during this period
Barriers to Enhancing Safety
• Safety not explicitly included as a factor in the planning process– Assumed that projects are “safe and efficient”
• Safety needs addressed with a limited solution set– Usually through independent infrastructure and
behavioral (402) planning efforts
The Use of Data in the Planning Process
1. Use data to incorporate safety as a discrete planning factor
• Safety Level-of Service (LOSS) measures developed as part of NCHRP 8-44
2. Use of data to promote a comprehensive approach to addressing transportation system safety
Safety as a Planning Factor
EnvironmentalEnvironmentalQualityQuality
ProsperityProsperity
Social equity/ Social equity/ quality of lifequality of life
VisionVision
EnvironmentalEnvironmentalQualityQuality
ProsperityProsperity
Social equity/ Social equity/ quality of lifequality of life
VisionVision
ProsperityProsperity
Social equity/ Social equity/ quality of lifequality of life
VisionVisionGoals and objectives
Performancemeasures
Goals and objectives
Performancemeasures
Alternativeimprovement
strategies
Data Analysis methods
Other sources for project
ideas
Alternativeimprovement
strategies
Data Analysis methods
Other sources for project
ideas
Systemoperations
Systemoperations
Systemoperations
PoliciesOperations strategiesInfrastructure projectsStudiesRegulationsEducation and awarenessFinancing strategiesPartnershipsCollaborative undertakings
Leads to…. Plan
Evaluation
Evaluation
Including as one product…
Implementation of strategies
TIP
Implementation of strategies
TIP
Needs Identification and Project Selection
Mission Statement
Implementation of strategies
Alternativeimprovement
strategies
Evaluationcriteria
Goals and objectives
Performancemeasures
Data Analysis methods
Other sources for project
ideas
Plan
Systemoperations
TIPProsperityProsperity
Social equity/ quality of life
EnvironmentalQuality
Vision
Safety includedin vision
Implementation of strategies
Alternativeimprovement
strategies
Evaluationcriteria
Goals and objectives
Performancemeasures
Data Analysis methods
Other sources for project
ideas
Plan
Systemoperations
TIP
EnvironmentalQuality
Vision
Safety explicitly stated in goals
Safety performance
measures
Goals, Objectives and Performance Measures
PerformanceMeasures
• Crashes per VMT
• Crashes per capita
• Hours of delay
• Congestion index
Objective Reduce rate of motor vehicle crashes
Decrease travel times for commuting
Safety MobilityGoal Ensure high standards
of safety in the systemProvide efficient and economic access to jobs, housing, and economic activities
PerformanceMeasures
• Crashes per VMT
• Crashes per capita
• Hours of delay
• Congestion index
Objective Reduce rate of motor vehicle crashes
Decrease travel times for commuting
Safety MobilityGoal Ensure high standards
of safety in the systemProvide efficient and economic access to jobs, housing, and economic activities
Goals, Objectives and Performance Measures
Needs Analysis and Identification
Implementation of strategies
Alternativeimprovement
strategies
Evaluationcriteria
Goals and objectives
Performancemeasures
Data Analysis methods
Other sources for project
ideas
Plan
Systemoperations
TIP
EnvironmentalQuality
Vision
Safety data continuously
collectedSafety included
in analysis
Safety strategies
considered
Analysis Methods
Current Tools:
• Before-After Analysis
• Hot-Spot Identification
• Safety Audits
Software Applications
Current Software Applications• Intersection Magic (Pd’ Programming Inc )
• SafeNET (UK Department of Transport)
• SafetyAnalyst (FHWA)
• PEDSAFE (FHWA—UNC)
• Interactive Highway Design Model (FHWA)
• Pedestrian and Bicycle Analysis Tool (FHWA)
Planning for the Future…
Can We Forecast Future Safety Needs?
• To plan for future safety needs, we must be able to predict what those needs will be
– Forecasting crashes at TAZ level is feasible and promising (NCHRP 8-44)
– Data can be used to predict and compare relative levels of future safety
Data Requirements and Methods
• Historical crash data (dependent variable)
• Data on relevant predictor (independent) variables– These should be data that are readily
available to transportation agencies and MPOs (e.g., road data, population data, land use data, etc.)
Example…
Log Likelihood: -394.8815 Parameter Estimate Std Error T-Statistic Popden .05078290568 0.0299586547 1.6951 Pminorpop -5.1819400372 .60288247573 -8.5953 Intden -4.8164757002 1.3908559352 -3.4630 Alpha 1 2.7587593688 .71727782129 3.8462
Log Likelihood: -2748.9182 Parameter Estimate Std Error T-Statistic Popden .10474820918 .01869781132 5.6022 Total_Emp .04979218698 .00412343184 12.0754 Intden 6.4856359666 .83426075467 7.7741 Cla3st 4.4337925363 .94892812674 4.6724 Cla4st 4.9236609811 .77657660279 6.3402 Cla7st 3.1058281681 .79507463581 3.9063 Alpha 1 2.1783925513 .11306661148 19.2665
Fatal Crashes
Injury Crashes
A Comparative Framework
Safety Level of Service (Kononov and Allery, with permission)
• Quantify the level of safety using a “report card”
• Communicate safety to other professionals (or elected officials)
• Define safety performance as an MOE
• Frame of reference for decision-making/planning
Applying a Safety LOS
Basic Concepts - LOSS• Safety performance functions used to determine
“expected” safety
• Identify LOS for safety (LOSS) based on difference between OBSERVED and EXPECTED safety at sites (intersections, road segments, pedestrian crossings, etc.)
• Categorize locations based on LOSS
• Diagnose safety problems
Urban 6-Lane Freeways(1989-2001) INJ+FAT - Sections => 0.9 Miles
0
5
10
15
20
25
30
35
40
45
0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000 200,000
ADT
APM
PY
- 1.5
+ 1.5
LOSS I
LOSS IV
LOSS III
LOSS II
Addressing Safety – Project Selection
Implementation of strategies
Alternativeimprovement
strategiesEvaluationGoals and
objectivesPerformance
measures
Data Analysis methods
Other sources for project
ideas
Plan
Systemoperations
TIP
EnvironmentalQuality
Vision
Safety partof criteria set
Safety integrated within plan
PoliciesOperations strategiesInfrastructure projectsStudiesRegulationsEducation and awarenessFinancing strategiesPartnershipsCollaborative undertakings
Leads to….
Safety integrated into products
Plan
Safety integrated within plan
Coordinated Planning and Analysis
• We’ve got new tools, now what do we do with them? – Planning and implementing safety
solutions is segregated into “Hard” and “Soft” approaches
– Software and analysis cannot provide a substitute for reasoned, interdisciplinary consideration of needs and opportunities
Barriers to Enhancing Safety
Safety is often inadequately addressed solely through design “improvements”
Where Are Safety Gains Really Coming From?
“Changes in highway infrastructure… have not reduced traffic fatalities and injuries and have even had the effect of increasing total fatalities and injuries… other factors, primarily changes in the demographic age mix of the population, increased seatbelt usage, and improvements in medical technology are responsible for the downward trend in total fatal accidents.”
Noland, R., “Traffic Fatalities and Injuries: Are Reductions the Result of ‘Improvements’ in Highway Design Standards?” Transportation Research Board 80th Annual Conference Proceedings CD-ROM, Washington DC (2001).
Coordinated Planning and Analysis
Brevard County MPO Pedestrian and Bicycle Safety Program
How Do We Use Data to Build Partnerships?
• Leverage role as data providers to build new partnerships– Planning agencies need expertise on the
availability, use, analysis and interpretation of safety-related data
– Providing data provides new inroads to the consideration of a holistic approach to transportation safety
Future Needs…
• There is a clear need to re-examine the current planning approach:– Fuller treatment of safety as an integral part of
the planning process– Design guidance that is based on a substantive
understanding of safety, rather than solely on operational performance
• Data is ESSENTIAL for the success of these efforts!