Wasatch 100 GIS Data and Maps

Welcome.  This page is intended for those wishing hyperdetailed maps and GIS data on the Wasatch 100 course, especially those who will be using GPS during training runs or the race. 

In the past I intended to break up the data on the on the course into geographic areas below.  I have decided to do that only with maps (below).  There is now just one master data packet: a shape file you can open in a CAD program, GPS Trackmaker, or G7toWin (highly recommended) (and then, with GPS Babel, GPS Trackmaker, ExpertGPS or other freeware, convert at your leisure into other formats).  I have also done a conversion of the shape file for Garmin and Lowrance users.   Data was acquired in 2005 using a Thales Mobile Mapper GPS, post-processed using the SLCU differential beacon.  Accuracy of most trackpoints is submeter

The map above shows a track taken of a slow walk along a 20' curbside in Salt Lake City.  Each color square is 10 feet wide.  The yellow points were plotted with a Garmin GPS III+ recreational GPS, and the red points were taken with the Thales Mobile Mapper, post-processed.  This is why I decided to remap the course with the Thales.

You will need to use a utility to upload these annotations to your GPS.  The easiest way to do this is to get a high quality software package, like AllTopo from iGage (www.igage.com) that supports open source data formats.  It costs no more than competitors (Maptech, Topo!), but is a far better product.

Barring buying AllTopo, I recommend you Google the input file extension (e.g. .shp), the output file you need (e.g. .gpx) and your GPS model.  Lots of open source folks out there (like GPS Trackmaker) are writing conversion software that will create the file you need to get the data into your GPS.  Beware, however, of your GPS’s waypoint limits—there are certainly too many trackpoints in these files to be converted into waypoints in all but the Magellan units that use big SD cards (if they even allow those cards to hold waypoint data—many models do not).

I am assuming that your interest in these annotations is to upload them to a GPS, and not to replot them on your own mapping software.  If you do want to plot them, and are not using AllTopo or a professional GIS package, you are almost certain to become frustrated.  If there was ever a reason for open source, amateur mapping software programs are it.  All of them—Topo!, Maptech, DeLorme, MapSource, MapSend (you name it)—use proprietary formats and may or may not accept the .shp file I have provided you.  But by using a conversion tool, you should be able to convert the annotations I have provided into something that will talk to your program.  Then, you will be able to reduce the number of trackpoints into a manageable number for your GPS’s on board memory.  Keep trying—you’ll get there.  If you hit a roadblock, and want to cry, email me at phil@phillowry.com.  I will try to get you to the next aid station.  ;-)

Please note that by sharing these files I am essentially giving you my source code.  Please give credit where credit is due if you redistribute this data or render maps or other product with it. 

Master Data File.  To use this shape file, COPY ALL THREE files into the same folder on your hard drive, and then open the .shp file in it from there.

Wasatch shape/Wasatch 2005 master 20050819_PL.dbf

Wasatch shape/Wasatch 2005 master 20050819_PL.shp

Wasatch shape/Wasatch 2005 master 20050819_PL.shx

Garmin users: for your convenience I have already converted the above into a Garmin PCX5 (*.grm) file, which you can use in Mapsource and extract trackpoints to your GPS. There are WAY too many trackpoints even for the best Garmin units, so go into your track points and filter them down.  I still do not know how to convert the trackpoints into waypoints, but am working on it. Here is the file:

Wasatch 2005 master 20050819_PL.grm

Lowrance users, here is your .usr file:

Wasatch 2005 20050819.usr

Maptech folks, here is a .txf for your use and pleasure:


The attached files are "milepost" files: 1001 waypoints, each representing 0.1 miles on the course (e.g. wpt133 would be milepost 13.2).  The start is assigned wpt1, so the whole series is off by 0.1.  Use G7toWin to convert the file into whatever format you like for your GPS:

wasatch 100.RXF


Ziggy Uibel's route files for Garmin users:


Maps (note: these are huge because they show every track point in the data file above)


Francis Peak



Mule's Ear


Mill Canyon




Measuring 100 miles of trail and dirt road poses unique challenges. Rough terrain can frustrate wheel and pedometer measurements for reasons hinted at in Zeno’s paradox (pace Heraclitus). Until GPS was invented, however, these were the only measurements available. In some instances even GPS modalities were ignored, and reliance instead was placed on preexisting federal or state agency measurements, which are often wrong themselves (for example, the Uinta National Forest continues to propagate the absurd notion that the Mt. Timpanogos Timpooneke Trail is 9.1 miles long, which is an exaggeration of nearly 25%!). This resulted in one (here unnamed) 100-mile race overstating its length at one time by over 10%. Some races simply say up front that their course is about 100 miles, such as Hardrock, which is brutally frank that it is a bit over 100 miles.

The Wasatch 100 has always mechanically field-checked its course measurements, and in 2001 I measured the current (then-new) course with a Garmin eTrex GPS and National Geographic Topo software. This was the first instance that GPS was used to measure the course. With the advent of better GPS equipment and better maps, I undertook the task again this year.

The course was measured in the first two weeks of July, 2004, using a Garmin GPS Map 60C with a Titan 3 external antenna. High gain was assured by attaching the antenna to a hat and wearing it on top of my head. I sacrificed fashion for science. The GPS was programmed to log a track point every ten feet or every second, whichever interval occurred more frequently. This interval was chosen because I thought ten feet to be the average leg a runner will travel on a bearing until deviating right or left (longer on road stretches, shorter on very rough trail).  It was also the only practical interval when limited to only 10,000 track points per session (about 22 miles). (As an interesting aside, the longer a stride length, the shorter the course. This is elementary calculus. Thus, the course is physically shorter for a tall person (like Tim Seminoff) than it is for a shorter person (like Laura Vaughn or Karl Meltzer). This advantage appears to be compensated for, in many shorter runners, by incredible lungs and muscles (shorter runners as group tend to fare better at Wasatch from year to year)).

The collected track points were then plotted into the computerized iGage topographic maps, which then computed the distances of the track after computing a 3D model of the track (this by superimposing it on the X-Y map plane and the Z-axis digital elevation model (1m resolution)).  iGage's AllTopo program makes the best digital maps available: these maps are far better updated than any other digital maps in existence, and the user interface is far more powerful and resilient.  Many thanks to them for donating their maps to the Wasatch 100 (www.igage.com).

Hand plotting was used in about 50 of the over 36,000 track points to correct deviations caused by snowfields or as-yet uncleared winter deadfall. Tracks were also cross-checked with orthographs (aerial photos), as shown by the 3D photo models of the course that accompany the 2D maps. My own knowledge was brought to bear in this regard, having run the race eight times and trained on the course hundreds of times.

Mapping v. measuring: is GPS as good at measuring as it is at mapping?

My main goal was to get plottable tracks on a map for reference: secondary was the goal of remeasuring the course.  But is consumer GPS the best measurement modality?  Professional-grade (submeter accuracy) GPS now is the standard for surveying, etc., but even this requires proper elevation compensation (accomplished through transits and trigonometry), which I approximated with the software’s digital elevation model.  But these surveying measurements are done with $5,000 portable professional units, not a consumer handheld.  How could I know that the GPS was as accurate as the old wheeled measurements of the course?  These have been highly accurate: Irv Nielsen's original wheel measurements were done with a Rolatape engineering wheel that was calibrated against steel tape laid along a trail to correct slippage.  Using GPS is more convenient, but, to pose the question again, is it truly more or as accurate?  After taking out my own Rolatape with the GPS, I discovered that a sampling rate of one point per ten feet was too infrequent, but a sampling rate of a point per three feet matched the wheeled distance (after slippage correction).  On August 28 I measured a 2.7-mile stretch of course with a sampling rate of three and a rate of ten.  The three-foot sampled portion came out nearly 1.5% longer.  Not surprising--three feet is just a bit longer than one's stride.  After multiplying this factor into all the data collected with the ten-foot sample track, I was able to achieve remarkably accurate results, thus showing the reliability of consumer GPS compared to even highly accurate wheels.

Another factor is human, not technical: over the course of the relatively huge foot distance of 100 miles, conscious cutting to the inside of every curve can have a significant effect (>1%).   This has been demonstrated by measurements of the Appalachian and Colorado Trails measured by the iGage team with a Trimble GPS that post-processed all GPS data every second and compared to taking the outside option.  So, to a certain degree, conscious choice can shorten the course and still keep you within the rules.

Given this fact, a deviation of 2% is considered acceptable and within the margin of error. It is your choice whether you deem the course 98 or 102 miles long, but I am confident that it is as close to 100 miles as is practicable.

For your convenience, I will soon make available the track that you should be able to import into most mapping software to plot the tracks on your own maps, or into a GPS to use for training runs (or the race, if you like). The only software I have encountered that does not allow this is Maptech’s Terrain Navigator, which uses its own proprietary export format that is wholly unsuited to anything but itself (a major product flaw). Also soon to be attached is the iGage annotation file for the entire course and the Topo *.tpo file, both of which will allow immediate importation of the actual course and data into either of these software products.

Oh, the burning question--how long is it?  According to the tracks, the course is 99.901 miles long.  Throw in an extra 2 or 3 hundredths (150 feet) for aid station traffic, etc., and, well, you get the picture.  It's 100 miles.

A final word.  The committee's integrity and hard work to ensure the course's length is tenacious and remarkable.  Irv's efforts to trail-calibrate what is considered the best engineering wheel made (the Rolatape) is beyond the call, and shows that Wasatch cuts the edge as far as course length validation is concerned. I trust I will never again hear finish-line banter about how such-and-such stretch must really be xyz miles.  Not so. I  hear that some other 100-milers still use mapping software only, forest service anecdote, small non-engineering wheels, or mountain bikes with odometers to measure length.  None of these modalities is acceptable compared to the standards of Wasatch.  If races that use those methods end up being 100 miles, the trail gods and lady luck must be smiling on them.  As for Wasatch, luck ain't got nothin'  to do with it.

Phil Lowry
Springville, UT
August 2004


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