Transcript No Slide Title - University of Virginia

Safety
• Judgment of acceptability of risk
• Subjective component
– Evaluates whether a given risk is acceptable
– Policies based on that judgment
– Policies determine trade off between a level of risk
and resources needed to reduce the risk
• Objective component
– Risk assessment
(Lanzilotta, 1995)
Center for Risk Management of Engineering Systems
University of Virginia, Charlottesville
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Evidence for Risk
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Traditional knowledge
Common-sense assessment
Analogy to well known cases
Experiments with human subjects
Review of inadvertent occupational hazard
Statistical analysis
Experiments on non-human organisms
Tests of product performance
(Lowrance, 1976)
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Investigating Risk
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Conditions of exposure
Identify the adverse effect
Relate exposure with risk
Estimate overall risk
(Lowrance, 1976)
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University of Virginia, Charlottesville
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Transportation Risk Assessment
• Probability
– Likelihood of an accident
– All events that lead to the accident
• Severity
– Outcome of an accident
– All events after the accident occurs
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University of Virginia, Charlottesville
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Transportation Risk Assessment
(cont.)
• Risk probability varies as a function of the state
of the system
• State of the vehicle
• State of the environment
• A system state is the result of several conditions
• Driver error
• Machinery failures
• Roadside hazards
(Lanzilotta, 1995)
Center for Risk Management of Engineering Systems
University of Virginia, Charlottesville
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Difficulties of Estimating
Transportation Risk Probability
• Accidents are rare events and difficult to
predict
• Little attention to the time period
preceding the accident
• Compound set of hazards and events
leads to the accident
(Lanzilotta, 1995)
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University of Virginia, Charlottesville
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Safety State Model
• Near collisions are more common than
accidents
• Identify near collisions and events that
lead to them
• Formulate response to reduce occurrence
of near collisions
• Reduce number of accidents
(Lanzilotta, 1995)
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University of Virginia, Charlottesville
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Accident Statistics
• Disadvantages
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Unreported accidents
Severity iceberg
First and most harmful event
Fatalities do not occur frequently enough to
be statistically predictive
– Random nature of road accidents
(Adams, 1996), (Michie and Bronsted, 1994)
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University of Virginia, Charlottesville
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Accident Statistics (cont.)
• Advantages
– Available and assessable
– Factual
– Public interest
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Examination of HTRIS
• Compare date gathering methodologies
using HTRIS
• Guide to collecting data from HTRIS
• Capabilities available in HTRIS
• Alternatives to HTRIS
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Methods to Gather Accident Data
• All accidents between two nodes
– Reveals all accidents
– Manually eliminate irrelevant accident data
• All fixed object accidents between two nodes
– Reveals fewer accidents by targeting relevant accidents
– Other accidents involving guardrail might be
overlooked
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University of Virginia, Charlottesville
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Methods to Gather Accident Data
(cont.)
• All run-off the road accidents between two
nodes
– Reveals fewer accidents by targeting relevant
accidents
– Other accidents involving guardrail might be
overlooked
• Comprehensive method
– Provides comprehensive data
– Inefficient and time consuming
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Guide to Collecting Data
Enter Road ID
Enter HTRIS
Press F 10 for node locator
Enter ‘y’ for node list
Is the furthest node less than five
miles away from the first node?
Enter County Code at “jurisdiction”
prompt
Enter ‘x’ at first node
Enter ‘y’ at last node
YES
NO
Press F 6 when done
Enter ‘x’ at first node
Press F 6 to analyze all accidents
Enter ‘y’ at furthest node within five
miles of first node
Hit enter to see summary statistics
Press F 6 when done
Type ‘y’ to see individual accidents
Hit enter to see Accident Record
Inquiry if more information is desired
Hit enter to see Vehicle Record
Inquiry if more information is required
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Repeat process for the remaining node on road (if nodes were
more than five mikes away), placing an ‘x’ at the node that
previously had a ‘y’ and a y at the furthest node within five
miles.
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Data Available from HTRIS
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Summary statistics
Individual accidents
Accident Record
Vehicle Record
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Summary Statistics
Parameter
Explanation
Significance
Fatal
Accidents
The number of accidents involving
fatalities that have occurred in the
specified corridor
information on exposure
Injury
Accidents
The number of accidents involving
injuries that have occurred in the
specified corridor
information on exposure
PD accidents
The number of accidents involving
property damage that have occurred in
the specified corridor
information on exposure
Persons
killed
The number of fatalities that have
occurred in the specified corridor
information on severity
Persons
injured
The number of injuries that have
occurred in the specified corridor
information on severity
The amount of property damage that
has occurred in the specified corridor
information on severity
The number of accidents that have
occurred in the specified corridor
information on exposure
Amount
PD
Total
Accidents
of
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Individual Accidents
Parameter
Explanation
Significance
Document
Number
The number used by the police
department to identify the accident
Will be useful if more detail
information on the accident is
needed.
Date
The date the accident occurred
Offset
from Node
The distance in miles from the
accident to the node
Useful for evaluation to compare
precise locations
Direction
The direction the vehicle was
traveling at time of accident
Useful for evaluation to compare
precise locations.
Collision
Type
The numerical code for type of
collision
Useful for screening and evaluation
phase to show the type of collisions
that relate to presence or absence of
guardrail.
Weather
The numerical code relating to the
weather at the time of accident
Might be useful for evaluation and
determination of safety
countermeasures by giving
information on accident trends.
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Individual Accidents (cont.)
Parameter
Explanation
Significance
Surface
Condition
The condition of the road surface at
the time of the accident
Might be useful for evaluation and
determination of safety
countermeasures by giving
information on accident trends.
Number of
Vehicles
The number of vehicles involved in
the accident
Might be useful for screening and
evaluation to determine the
relevance of guardrail
Number of
fatalities
The number of fatalities involved in
the accident
Useful for evaluation by providing
information on severity
Number of
pedestrian
fatalities
The number of pedestrians killed
due to the accident
Number of
injuries
The number of injuries involved in
the accident
Number of
pedestrian
injuries
The number of pedestrians injured
due to the accident
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Useful for evaluation by providing
information on severity
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Accident Record
Parameter
Explanation
Significance
Document
Number
Road
System
County
The number used by the police
department to identify the accident
Distinguishes between primary and
secondary roads
The county the accident occurred
Intersect
Route
Offset
The Intersection Route
Redundant – information available
in summary statistics
Useful for distinguishing between
primary and secondary
Useful for obtaining accidents
specific to a particular county
Useful for screening by providing
information on the routes
Redundant – information available
in summary statistics
Number of
lanes
Facility
Type
Road
Defects
Type of
Collision
The distance in miles from the
accident to the node
The number of lanes on the route
The type of road
Defects on the road
The type of collision
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Useful for evaluation – may reveal
the significance of guardrail
Redundant – information available
in summary statistics
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Accident Record (cont.)
Parameter
Explanation
Significance
# vehicles
The number of vehicles
Redundant
# killed
The number of fatalities
Redundant
# injured
The number of injuries
Redundant
Date
The date the accident occurred
Redundant
Route
The route the accident occurred on
Useful for screening
City
The city the accident occurred in
Type of
environment
Node
Surface Width
Surface Type
The surface of the road
Traffic
Control
Severity
The traffic control
The severity of the accident
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Might be useful for evaluation and
determining countermeasures
Information on the adverse effects
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Accident Record (cont.)
Parameter
Explanation
Significance
Weather
The numerical code relating to the
weather at the time of accident
Redundant – information available
in summary statistics
Pedestrians
killed
The number of pedestrians killed due
to the accident
Redundant – information available
in summary statistics
Pedestrians
Injured
The number of pedestrians injured
due to the accident
Redundant – information available
in summary statistics
Property
Damage
The amount of property damage
involved in the accident
Useful for evaluation by providing
information on adverse effects
Accident
lane
Number
The lane the accident occurred
Might be useful for evaluation by
revealing the relevance of guardrail
Time
The time the accident occurred
Might be useful for evaluation and
determining countermeasures by
revealing trends
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Accident Record (cont.)
Parameter
Explanation
District
The district of the accident
Shoulder
Width
The width of the shoulder where the
accident occurred
Useful for evaluation by describing
the location
Surface
Condition
The condition of the road surface at
the time of the accident
Redundant – information available
in summary statistics
Alignment
(Curve, dip, grade, hillcrest, not
stated, other, straight)
Useful for evaluation in determining
exposure
Major
factor
The most contributing factor to the
accident
Might be useful for evaluation and
determining countermeasures
Zone of
Impact
What is this?
Light
The lighting at time of accident
Federal
Aid
(Final, Primary, Secondary, Urban,
Not built etc.)
Functional
Class
(Freeway, Rural, Urban)
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Significance
Might be important for evaluation
and determining countermeasures
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Vehicle Record
Parameter
Explanation
Significance
Vehicle
Type
Estimated
Speed
Vehicle
Maneuver
Vehicle
Placement
Vehicle
Skidding
Fixed
Object
The type of vehicle
Might be useful for evaluation and
determining exposure
Useful for evaluation and
determining exposure
Useful for evaluation to determine
significance of guardrail
The estimated speed of the driver
The control of the car at the time of
the accident ( run off the road, etc.)
The involvement of skidding to the
accident
The type of fixed object involved in
accident
Tractor
Length
Trailer1
Length
Trailer2
Length
Trailer
Width
Center for Risk Management of Engineering Systems
Might be useful for evaluation
Useful for evaluation to determine
significance of guardrail and
exposure
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Vehicle Record (cont.)
Parameter
Explanation
Significance
Vehicle
Condition
Defects in vehicle
Might be useful for evaluation to
determine trends and significance of
guardrail
Driver Age
Age of driver
Driver Sex
Sex of driver
Driver
Action
The action of the driver responsible
for the accident (i.e. sleeping,
swerving, drinking)
Might be useful for evaluation to
determine significance of guardrail
Driver
Condition
Defects of driver
Might be useful for evaluation to
determine significance of guardrail
Driver
Drinking
The presence or absence of alcohol
from the driver
Might be useful for evaluation to
determine significance of guardrail
Driver
Visibility
The vision of the driver at the time
of accident
Number
Axles
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Synthesis of Relevant Data on
HTRIS for Screening
Individual Accidents
Offset from Node
Collision Type
Number of Vehicles
Number of Fatalities
Number of Injuries
Accident Record
Property Damage
Shoulder Width
Severity
Vehicle Record
Fixed Object
Vehicle maneuver
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Limitations and
Recommendations
• Limitations
– Time consuming to search all accidents
– 15+ hours for New Kent County for limited amount of
data
– Must examine multiple screens to obtain all relevant
data
• Recommendations
– Search database without limiting search to nodes
– Enter search parameters of interest and receive a report
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