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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Collision Diagramming Program: Utilizing ArcMAP/GIS

This paper describes how when analyzing traffic accidents, transportation engineers must have a clear understanding of the contributing factors. How would an analyst know if a sight distance restriction may have contributed to an accident? How would an analyst know if a traffic signal may improve the safety of an intersection? The answer is they wouldn’t if they are not seeing all possible influences with a particular pattern of traffic accidents. But how can analysts see all the possible influences graphically on a collision diagram? The answer to this question is geographic information system (GIS). Combining GIS and collision diagramming offers the ability for traffic engineers to understand all of the spatial implications with a particular area under investigation. Accident data can be analyzed with the true curvature of the roads, aerial photography, right-of-ways, edge-of-pavements, landscape and zoning information, and signage to name a few. Until recently, Gwinnett County, Georgia, like so many other counties and cities, did not have the capability to digitally integrate their traffic analysis with a GIS. Their existing traffic diagramming system did not incorporate the true spatial orientation of the roads. Instead it diagrammed the accidents over what is termed a generic version of the roads, which is where the roads are drawn as two perpendicular lines. Roads diagrammed in this fashion are less informative than a geographic system. The only purpose they serve is to identify the road names where the accidents are occurring. This would be okay except accidents occur in the real world, where roads intersect at irregular angles and have curves. This is especially true in Gwinnett County, which has a complicated transportation infrastructure. Additionally, the County had no way to plot mid-block accidents. Mid-block accidents are classified as all accidents that occur between intersections. One of the most frequent mid-block accidents occur when someone pulls from a private driveway onto a busy street. The old method of diagramming mid-block accidents meant running database queries and drawing the diagrams by hand. This process could take hours, depending on how many accidents occurred at the specific location. The County researched several off the shelf products but was unable to find a system that met the specific requirements. The main problem was that no application would work within the existing Oracle environment or within the existing GIS environment. Some systems claimed to be GIS, but they did not place and orient accident symbols geographically on a map. They mostly just offered the ability to create accident density maps. The County had an established GIS program, and they knew the potential of using a GIS to build better diagrams. To move forward with their ideas, they contracted with Burns & McDonnell Engineering to develop a real-world solution for collision diagramming using ArcGIS Desktop. Burns & McDonnell worked with the County and developed an ArcView extension known as CDARE, which Burns & McDonald currently calls True Traffic. CDARE gives traffic engineers the ability to diagram both intersection and midblock accidents using all of the sophistication and power of GIS. Gwinnett County Department of Transportation (GCDOT) currently captures crash data in an Oracle database. The county base-line map is available in GIS. For a given intersection or a road segment (), CDARE queries collision information from the collision database (Oracle), matches each selected crash with a symbol taken from many stored in CDARE’s library, and plots one symbol per crash onto an appropriately zoomed-in intersection or road segment.

Language

  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures;
  • Pagination: 20p
  • Monograph Title: 2006 ITE Annual Meeting and Exhibit Compendium of Technical Papers

Subject/Index Terms

Filing Info

  • Accession Number: 01036909
  • Record Type: Publication
  • ISBN: 1933452161
  • Files: TRIS
  • Created Date: Nov 15 2006 4:22PM