North Dakota Pilot GPS Project Presenter: Judy L. Froseth Lory Harsche

The Problem: Crash location information has been maintenance intensive and difficult to code. Engineering staff has expressed concerns with these problems.

GPS Pilot Objectives: Collection –Ensure the data format is accepted and usable Test data entry screens for data acceptability Test data retrieval to ensure proper format –Ensure data collection is simplified Easy use of GPS units Quality instructions provided to the officers

GPS Pilot Objectives: Collection (continued) –Collect crash reports with GPS data Ensure significant quality of crash reports in pilot Review the handwritten data format for correctness Ensure GPS unit provides data consistent with data standard Check GPS unit configuration options for consistency Ensure data is collected when the GPS unit has a strong signal lock

GPS Pilot Objectives: Collection (continued) –Collect law enforcement officers’ feedback Discuss GPS use, function, performance, questions, issues

GPS Pilot Objectives: Use –Import/export crash data into a GIS system for analysis, testing and review Provide the system with GPS and crash report data Review the export/import process for efficiency, make changes Use electronic and paper node maps to compare GPS and node point location data – Provide feedback to officers

GPS Pilot Objectives: Use (continued) –Have experts examine the data results to ensure data meets accuracy requirements, is consistently collected and is usable Assemble the panel of experts Determine what is required to analyze the data Review the analysis, make recommendations to correct problems Discuss statewide implementation

GPS Pilot: Revise the MVCR form to provide space for GSP coordinates Required close communication between: –Traffic Safety –Planning and Programming –Information Technology Form was revised and printed in December 2001

GSP Pilot: Two law enforcement agencies: –Bismarck Police Department in January 2002 –Cass County Sheriff’s Office in February 2002

GSP Pilot: GPS Units: –Magellan Meridian GPS at $235 each

GSP Pilot: GPS Units: –Garmin eTrex Legend at $265 each

GSP Pilot: How did officers view this “extra” duty? –As part of the crash data collection process to provide more accurate data –Collection of GPS data became part of their daily routine Which GPS units were preferred? –All officers preferred the Megellan, based on ease of reading the numbers

GSP Pilot: GPS Unit: –Magellan Meridian GPS at $235 each

GSP Pilot: How has the durability been? –There have been no known issues What have been the pitfalls/problems? –GPS units provide a continuously reading number –Officer must select the 5th decimal digit from a fluctuating readout –The 5th decimal represents roughly 1-5 feet of change

GSP Pilot: Have officers reported difficulty receiving signals/getting a reading? –One crash report indicated a reading was not possible due to heavy rains –Officers are not returning to the scene when the report is completed elsewhere

GSP Pilot: What is the battery life? –Battery life depends on frequency of use –Bismarck PD uses about 2 sets per month –Cass County used original batteries for over 4 months

Technical Field Accuracy Comparison: Manufacturer’s specifications on accuracy: –Magellan Meridian GPS WAAS enabled up to 3 meter accuracy –Garmin eTrex Legend 3 Meters – 95%, 15 Meters – 5%

Technical Field Accuracy Comparison: Field Accuracy Test Comparison –Based on 5 random locations near the Bismarck Capitol –Tests were performed in a side by side comparison mid-day June 5th –Trimbal Pro/XRS GPS unit was used as the comparison

Technical Field Accuracy Comparison: Radial difference in feet from the point identified by the Trimbal: Maximum Minimum Average Magellan52 feet16 feet24.8 feet Garmin36 feet1 foot16.2 feet

Data Collection/Preliminary Results: As of July 26, 2002, 300 total crashes have included GPS data About 30% of crashes reported by the 2 agencies have GPS coordinates Initial analysis identified data collection/entry errors, requires a check A non-labor intensive checkpoint process is being worked out