Pilot projects test GIS in crash investigations

A just-completed pilot project sponsored by the Federal Highway Administration has tested the use of GPS, GIS and combinations of both in accident investigations. In Dane County, Wis., one of four sites tested, officers employed the technologies to see if they would make collecting and managing accident information quicker and more efficient.

During the test, officers used a GPS receiver mounted on a laptop computer and on-screen maps to locate the site of vehicle crashes and fill in the accident forms. Back at the station or highway department, information collected with the handheld units could then be transferred to a server, creating an up-to-date repository of crash positions and particulars. The GIS software was then used by department analysts to query the records and show the results spatially as a map. The idea is that, eventually, the information will be used by public and private agencies to make the county’s roads safer.

The test built on two previous GIS research projects conducted by the Wisconsin DOT (WisDOT). Additionally, the state legislature has approved the Wisconsin Land Information Program, which encourages counties to automate parcel maps. The present study benefits from both efforts, applying the concepts of dynamic segmentation and building a local GIS road map from the parcels already automated.

Dane County consists of gently rolling, mostly glaciated land, covering 790,000 acres in south-central Wisconsin. It boasts a rapidly growing population whose density varies from fewer than 40 people per mile in the rural areas to more than 640 people per mile in the city of Madison and its outlying communities.

The county’s sheriff’s office employs 320 full-time deputies who respond to more than 175,000 calls for service in areas of the county not policed by full-time municipal officers. Of those calls, more than 2,400 involve traffic crashes. When an injury occurs or property damage exceeds $500, the sheriff’s office must collect and provide data about the crash to WisDOT. Officers complete a police accident report, the most recent version of which is a scannable document used by all of the state’s law enforcement agencies. This automation project provides a tool for the officer to register the location fields of the form by linking it to the GIS road map.

Four kinds of portable computers (a non-pen-based and three types of pen-based systems), as well as GPS receivers, were used in the project. Officer Information Managers, AMS, Arlington, Va., was used to collect all crash data except location. ArcView 2.1, ESRI, Redlands, Calif., was the GIS software. A crash location application was written using Avenue, ArcView’s object-oriented scripting language.

During the test, officers used the OIM to begin the crash-data collection process. ArcView was initiated when the officer was ready to collect information on the crash location. By pointing to on-screen maps with the pen, crash location could be collected and automatically transferred to the OIM thorough dynamic data exchange (DDE). When the application is used in conjunction with a GPS receiver, the readings of the GPS will be transferred to a map, and the officer could adjust the crash location if necessary. By pointing to a spot on the map, the officer could zoom to the accident’s location and indicate the crash site for the report by touching the pen to the screen at the correct position.

If the point is at an intersection, the officer would then be asked to verify or change the two intersecting road names. If not, the distance to the nearest cross streets would be computed and presented to the officer for adjustment.

Township/municipality codes, roads with names, and predominant direction and traveled mileage from intersection to intersection are the core data embedded in the road map. This data was created by the Dane County Land Information Office by editing parcel maps and using the files to build the road database. Digitized parcel maps were available by township from the Department of Planning and Development.

These parcel maps allowed for the retrieval of parcel right-of-way lines and centerlines. Ultimately, project planners say they would like to use the system to collect other crash data, such as pavement conditions.

This article was written by Eva Serra, a senior planner with the Dane County Planning and Development Department, and Paul Pisano, a research highway engineer with FHWA’s Turner-Fairbank Highway Research Center in McLean, Va.