Arkansas State Highway and Transportation Department’s Crash Location Tool -
Recording and Analyzing Crash Information
May 30, 2013
Summary of the Federal Highway Administration’s Quarterly Webinar: Applications of Geospatial Technologies in Transportation
These notes provide a summary of the PowerPoint presentation discussed during the webinar and detail the question and answer session that followed the presentation.
The presentation is available upon request from the webinar speaker, Sharon Hawkins (Sharon.Hawkins@arkansashighways.com).
The webinar recording is available at: https://connectdot.connectsolutions.com/p2xo4mimbcs/.
Section Head Mapping and Graphics
Arkansas State Highway and Transportation Department
Approximately 50 participants attended the webinar.
Introduction to Presentation
Mark Sarmiento of FHWA thanked participants for joining the webinar. This webinar was the eighteenth in a quarterly series of FHWA-sponsored webinars. The series deals with the application of geographic information systems (GIS) and other geospatial technologies to transportation. This webinar focused on the Arkansas State Highway and Transportation Department's (AHTD) Crash Location Tool, which is used for recording and analyzing crash information.
The State of Arkansas contains over 16,400 miles of state highway, the 12th largest state highway system in the country, and over 15,400 miles of other roads eligible for federal aid. Most crashes in the state occur on state highways (60 percent). Seventy percent of all crashes also occur in urban areas. However, 70 percent of all fatal crashes in the state occur in rural areas; two-thirds of rural crashes are roadway departure crashes.
Locating Crashes: 1970-2011
Prior to the development of the Crash Location Tool in 2011, AHTD used a variety of methods to locate and maintain crash data. Starting in 1970, state, county, and local law enforcement identified crash locations using county route, section, and log mile. AHTD printed large maps with log miles written by hand for law enforcement reference. Law enforcement had difficulty providing correct log miles due to the fact that log miles were not a common unit of measurement, difficult to correctly identify using a paper map, and one of 52 data points law enforcement officials were required to collect per crash. Even though the maps displaying log miles were available digitally starting in 1999, many law enforcement still used paper maps. Because of these challenges, AHTD employed crash locators, people to check each piece of datum using a complex tabular road inventory system stored in paper form.
In 2004, these AHTD crash locators switched to using a linear referencing system (LRS) to relocate crash location data. Once a route segment was digitized, AHTD added key fields such as the county, route name, section of the route, and beginning and ending log mile. The Department also used 911 centerline routes, part of a project by Arkansas's Geographic Information Office, to supplement its own LRS. By using this information, AHTD crash locators were able to more easily check crash data provided by law enforcement by hovering over a segment with a mouse and checking its identifying information.
However, most law enforcement officers did not have access to this software and were unable to improve the accuracy of their reported log miles. At one point, AHTD purchased 50 global positioning systems (GPSs) for law enforcement to use at the scene of a crash to improve location data. This anticipated solution was unsuccessful.
Crash Location Tool
In February 2011, the state experienced a major snowstorm. The existing crash location process was unable to provide useful real-time data to law enforcement, so a county sheriff challenged AHTD to improve its system. AHTD decided to use GIS to place a virtual point every 100 feet along the road LRS, creating the Crash Location Tool. Each point carried the key attributes of county, route, section and exact log mile. A spatial intersection query added other important information to each point, such as type of road, number of lanes, etc.
AHTD saved these points in a Keyhole Markup Language (KML) file. This file is easily shared via e-mail, FTP site, ArcGIS Online, and Arkansas' GIS clearinghouse. Law enforcement can now use Google Earth or ArcGIS Online to click on a point and extract important information, such as log mile, about a crash location. This can be done in the field, using ArcGIS Online on a mobile device, or in the office. Additionally, law enforcement can use Google Street View to better locate crashes on frontage roads and other non-main lane roadways.
The tool AHTD developed not only improved the efficiency of the crash location process, but also improved its accuracy. For example, previously only one log mile was used to identify crashes along a two-mile long bridge. Now, law enforcement agents can use one of approximately 100 points to identify a crash location along the bridge.
Training and Outreach
AHTD trained law enforcement agencies to use the new Crash Location Tool through conferences and one-on-one meetings. At least 42 agencies now have access to the tool, and approximately 50 percent of crashes in the state reported that they now use it. The biggest user is the Arkansas State Police. AHTD has received very positive feedback regarding the tool.
There are a number of ways AHTD can use this more accurate, more efficiently processed data to improve safety. For example, the Department can run queries on crash data to identify areas that need targeted safety initiatives. In October 2012, AHTD used an analysis of median crossover crashes in Arkansas to justify adopting a policy to install cable median barriers on over 398 miles of Arkansas roads in the next three years. Crash data were also used to demonstrate the need for installing rumble strips on the Arkansas highway system, particularly in rural areas. AHTD has installed over 1,000 miles of rumble strips to date.
AHTD uses Intergraph's Incident Analyst along with the Crash Location Tool to more quickly identify crash clusters. The Department can now:
- Develop a crash cluster map in two minutes instead of four hours.
- Easily count the number of crash events within an area boundary and find crashes that occurred in the same location.
- Play a movie (using a tool called “change over time”) that maps crash data over time.
- Quickly build charts that summarize crash data temporally. These charts are especially useful for public meetings.
AHTD will continue to update its LRS system and plans to add all public roads to the state LRS in the next five years. Law enforcement will then be able to locate all crashes, not just those that occur on a state system. The Department will maintain a live version of LRS for use and save archived copies each year. The updated LRS will also depict divided highways with two centerlines by including both log direction and anti-log direction. Lastly, starting in 2014 the Arkansas state police plans to use a paperless crash report submission system called “eCrash.”
Question and Answer Session
It sounds like your new system is easier for law enforcement to use, but are you still experiencing any difficulties in getting accurate location information?
Law enforcement officers have to enter in the data from Google Earth, so the information is still subject to human error. However, AHTD has decided that as long as a law enforcement officer is using the Crash Location Tool, the Department does not need to relocate the data. This allows AHTD to access the crash data in half the time (eight months instead of 1.5 years). Location accuracy concerns are another reason the Department is looking forward to using eCrash, as the system will automatically enter log miles into the crash report.
Is there a way to conduct hot spot analysis in ArcMap? Does this provide a number count along with the display?
Although ArcMap has hot-spotting capabilities, since AHTD uses GeoMedia as its GIS platform, using ArcMap for this purpose is not something staffs are currently trained to do.
How did AHTD discover Intergraph's Incident Analyst?
Intergraph presented a webinar to the AHTD that showcased their Incident Analyst product. Using crash data from Ohio DOT, they were able to demonstrate the different tools within the Incident Analyst product with real world data and analysis.
What level of accuracy would AHTD like to achieve? Plus or minus 50 feet?
Plus or minus 50 feet would be ideal. That is why AHTD decided to place a point every 100 feet in the Crash Location Tool. Before the Department implemented the tool, in some cases the reported location was up to 0.5 miles away from the actual location. AHTD now receives reported locations that are very close to the actual crash location.
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