1. Moving Toward Spatial Access: Lessons Learned
Daniel Carter
UNC Highway Safety Research Center
Presented at the Traffic Records Forum, August 6, 2017
New Orleans, LA

2. Background HSIS roadway and crash data warehousing process involves:
Acquiring data
Managing data
Delivering data
Data format has always been flat or tabular files

3. Background Traditionally fulfilled data requests in tabular format:
Roadway segments of a certain type with crash counts attached
Crashes of a certain type with roadway characteristics attached

4. Background
States are increasingly using GIS format for crash and roadway data
Development of the spatial road network is the result of the previous “centerline based” road inventory adapted to a spatial map to fulfill federal reporting requirements
Researchers want spatial data
How does the HSIS process need to change to accommodate spatial data?

5. Objective
Develop a process for creating a spatial representation of HSIS data

6. Staffing UNC HSRC – Daniel Carter, David Harkey, Forrest Council
UNC Carolina Population Center – Brian Frizzelle

7. How We Started Initial plan: Pilot state – Ohio
Replicate the HSIS process (acquire, manage, distribute) all within the spatial environment
Use the spatial data (road and crashes) available from the states
Pilot state – Ohio
Acquired Ohio roadway and traffic data from their website
Acquired one year of spatial crash data (2013) from Ohio DOT staff

8. Problems Differences in number of road segments
525,000 segments in spatial vs 32,000 segments in HSIS tabular file
Differences in number of crashes
HSIS tabular data only has state road crashes; spatial data has all public road crashes
Differences in attributes/fields
only about a 40% match in specific fields between spatial and HSIS tabular road files

9. New Plan
Continue to use HSIS tabular (traditional) data as the basis for all parts of the process
Use spatial data only for spatial position
This was the turning point

10. New Challenge
We could not simply use the spatial network available online from the state
We wrongly expected that the route naming convention would be the same between the traditional roadway data (what HSIS has been receiving) and the spatial roadway data
Some were radically different (CA) and some were slightly different (NC)

11. New Challenge
We had to work with each state to figure out their route naming scheme in the spatial data and how to translate that to match up to the route ID system used in HSIS roadway data
We created “custom” HSIS spatial road networks for each state (added route ID fields to allow joining to HSIS data)
NLF_ID CATHCR00232**C
cntyrte ATH0232R

12. New Process
Custom spatial files developed for various years, depending on the availability from the state:
CA: 2014
MN:
NC:
OH:
WA: 1999,

13. New Process
Develop HSIS tabular output (road segments or crashes) to fulfill data request
New optional last step: Convert data request to spatial format
Map road segments or crashes as route events in GIS, using the custom spatial network as the “skeleton”
Export as shapefile or feature class
Deliver to data requester

14. Modifications to Annual Process
Additional Steps for Spatial Data
Acquire data
Acquire current version of spatial road network
Ensure that the network contains all attributes needed to merge with HSIS tabular data
Manage data
Identify route IDs
Modify route IDs as needed to match HSIS route designation.
Create LRS routes if the State’s spatial data does not contain LRS routes
Deliver data
Convert HSIS tabular data to ArcGIS readable format
Develop spatial file for data delivery

15. Modifications to Annual Process
Additional Steps for Spatial Data
Acquire data
Acquire current version of spatial road network
Ensure that the network contains all attributes needed to merge with HSIS tabular data
Manage data
Identify route IDs
Modify route IDs as needed to match HSIS route designation.
Create LRS routes if the State’s spatial data does not contain LRS routes
Deliver data
Convert HSIS tabular data to ArcGIS readable format
Develop spatial file for data delivery

16. Modifications to Annual Process
Additional Steps for Spatial Data
Acquire data
Acquire current version of spatial road network
Ensure that the network contains all attributes needed to merge with HSIS tabular data
Manage data
Identify route IDs
Modify route IDs as needed to match HSIS route designation.
Create LRS routes if the State’s spatial data does not contain LRS routes
Deliver data
Convert HSIS tabular data to ArcGIS readable format
Develop spatial file for data delivery

17. Modifications to Annual Process
Additional Steps for Spatial Data
Acquire data
Acquire current version of spatial road network
Ensure that the network contains all attributes needed to merge with HSIS tabular data
Manage data
Identify route IDs
Modify route IDs as needed to match HSIS route designation.
Create LRS routes if the State’s spatial data does not contain LRS routes
Deliver data
Convert HSIS tabular data to ArcGIS readable format
Develop spatial file for data delivery

18. Issues (and Opportunities) for the Future
Data delivery will likely be solely in spatial format
Available attribute data may change
Much more non-state mileage available
Spatial linework is/will be stored separately for each direction of a road
Defining a single section of road may be difficult
Crashes may begin to be attributed to one side or the other
Volume data may be split across the sides of the road
Difficult in the short run, but may provide enhanced safety analysis possibilities in long run

19. Questions and Discussion