Are tracks longer than routes?
Problem Statement
Assess the magnitude by which route-based estimates differ from track-based estimates for a sample of data that has been used for planning or could be used for planning.Summary
This paper distinguishes between routes that are drawn over maps and tracks that are recorded with GPS devices. Both routes and tracks are polygonal path representations of the real paths that we travel over the earth. Tracks are very handy for obtaining distance and elevation gain. They can be downloaded from sites where users share the tracks from their trips. They have the advantage over routes in being an actual record of the path of the device while the user was hiking a trail. Routes are still necessary when there is no previously-recorded track.Routes have practical limitations on the number of route points that can be drawn. They are generally subject to bias from undersampling. Tracks are subject to undersampling error to a lesser extent than routes, tracks usually being more detailed with more track points. In addition, tracks are subject to satellite error on the order of 5 or 10 meters per track point. If the device records at too high a sample rate, the track will overestimate distance and cumulative elevation gain due to the accumulation of satellite errors.
The purpose of this research is to assess the magnitude by which route-based estimates differ from track-based estimates for a sample of data that has been used for planning or could be used for planning. By paired comparisons, we difference the length measured by a route with one measured by a track, the two both being representations of the same earth path. We find that length measurements from tracks average 0.65 miles longer than those from routes. This difference is about 12% of the average length of the routes in the data set. Using the same methodology, we find that elevation gain measurements do not differ signficantly between routes and tracks.
Summary of length difference (track - route) for three route types
Read the Details
- Are tracks longer than routes? .
- Technical paper, rendered with R Markdown, contains discussion, data analysis approach, results, conclusions and embedded code in R.
- Routes versus tracks data set.
- The routes versus tracks data set used in the research, 34 observations on 8 variables, .csv format.