1. South Carolina DOT’s Approach to Analyzing and Classifying Curves for Safety Planning
Roadway Design Planning Session
Jay Adams, Industry Consultant
Bruce Aquila, Sr. System Consultant
Wednesday October 28, 2015

2. Identify/Classify Curves on Statewide Data Set
Problem Definition
How Does the DOT:
Identify/Classify Curves on Statewide Data Set
Prioritize Safety Programs to Remediate Curve Safety Issues
Quantify Safety Data and Performance Measures to Support Actions
Road Safety Audits
Passing Restriction Analysis
11/22/2018

3. Many States Lack Curve Data in DOT Data Sets
Challenges
Large Data Volumes
Many States Lack Curve Data in DOT Data Sets
DOT Safety Data is Related to Primary Routes and LRS Data Sets
What is a Curve? When does it begin and end? (Spirals)
11/22/2018

4. Relate Extracted Data to States Data (ETL) Methodology:
Approach
Leverage TomTom Data
Geometry
Advanced Driving Attribution
Extract Key Elements for the State
Relate Extracted Data to States Data (ETL)
Methodology:
Identify Interpret Curve Information
Determine Direction of Curve
Processing tolerances (10 ft. radius difference)
Group Resulting Curves
Match Curve Points
Generate Result Files
Advanced attribution:
Physical - Height, weight, length, width, weight by axle
Operating – Hazmat, truck speed limits, truck maneuvers, idling and jake brake
General – truck restrictions, truck preferred, immediate access
Vehicle type - # of axles, # of trailers, no commercial vehicles
Data Matching:
Within 20 feet on main roads
Advanced matching based on road names (i.e. middle of roadway only 1 match vs. at intersections)
Processing tolerance manipulated at run time
Ramps and some intersections have larger data discrepancies
11/22/2018

5. Curve table LRS Keys/Measures Curve Radius Curve Length Curve Types
Results
Curve table
LRS Keys/Measures
Curve Radius
Curve Length
Curve Types
Geometry
Attributes
Descriptions ID
The unique identifier for the roadway
LRS_KEY_1…N
State LRS Keys (Up to 4 columns to define the LRS key).
Closest State maintained roadway will be selected.
This will be NULL if a State Road is not within the defined search tolerance.
BEGIN_MEASURE
State LRS begin measure
Closest State maintained road selected. Measure derived from interpretation of State LRS segment measures.
END_MEASURE
State LRS end measure column.
Closest State maintained road selected. Measure derived from interpretation of State LRS segment measures.
CURVE_RADIUS
Curve radius derived from commercial data in feet
Values from commercial data converted to a radius in feet. Acceptable radius values will be defined between 100 and 3,000 feet.
CURVE_LENGTH
Curve length derived from commercial data in feet.
CURVE_TYPE
Classification of curve (simple compound, reverse).
GEOMETRY
Curve geometry as defined in the TomTom data for reference.
Geometry stored as Oracle SDO_GEOMETRY and projected into same coordinate system as State LRS feature.
CURVE_TYPE
Descriptions
Simple
One simple curve with straight roadways on with end
Compound
Two or more consecutive simple curves that arc in same direction
Reverse
Two or more consecutive simple curves that arc in opposite direction
In cases where a compound curve meets a reverse curve the curves on either side of a reverse curve will be flagged as a reverse curve.
11/22/2018

6. ©2013 Intergraph Corporation
Safety Planning
11/22/2018
©2013 Intergraph Corporation

7. Fewer Fatalities and Casualties Better Infrastructure Preservation
Benefits
Curves Look Accurate (Reflect DOT Data)
Data Integrates into DOT’s Existing Safety Processes:
High Density Crash Location
Road Safety Audits (Identify Potential Projects)
More Accurate Ranking of Locations
Support Passing Restriction Safety Analysis
Expedited HSIP Reporting
Fewer Fatalities and Casualties
Better Infrastructure Preservation
11/22/2018

8. Enterprise Safety Analysis
Part of a Holistic Safety Analysis Program
11/22/2018

10. Thank You Bruce Aquila Hexagon Safety & Infrastructure
Jay Adams
Hexagon Safety & Infrastructure
Hexagonsi.com