Halfmile’s PCT App is on 10,631 Smartphones

An Android phone running Halfmile's PCT app.

An Android phone running Halfmile’s PCT app.

We know a lot of hikers are using our Pacific Crest Trail app but the numbers are even surprising us.

Halfmile’s PCT app is starting it’s fourth hiking season installed on more than 10,631 smartphones and we expect the numbers of hikers using the app to grow over the next few months.

About two weeks ago Halfmile’s PCT app was updated for the 2015 hiking season and this gives us an opportunity to see how many times the app was recently updated and count how many smartphones it is currently installed on. Most smartphones update apps automatically when they have an internet connection.

Halfmile’s PCT app is available free for both Apple iPhone and Google Android phones. Apple and Google report statistics somewhat differently, but here is what we know as of March 31st:

  • The iPhone version of the app was updated 5,620 times in the past two weeks.
  • The Android version of the app is reported by Google to currently have 5,011 active installs.

Google provides more information than Apple about things such as the model of phone, Android OS version, and cell phone company used. We found the cell phone company information especially interesting. Here are the cell phone companies of our 5,011 Android phone users:

Verizon 40%
AT&T 16%
T-Mobile 10%
Sprint 8%
US Cellular 1%
Virgin Mobile 1%
Aio 1%
TELUS Mobility 1%
Other 22%

A minor revision to the Halfmile app is being released to address stability issues and correct a few of the waypoint descriptions. The Android update is available now, the iPhone update should be approved by Apple in about a week. We encourage hikers to always update to the latest version of the app.

Alternatives to the PCTHYOH app

We noticed recently that Ruffwork’s popular PCTHYOH app is no longer available from the Apple iTunes app store. The app was widely used by Pacific Crest Trail hikers to store Halfmile maps for offline viewing when cellular or wi-fi internet connections are not available.

Sadly, Ruffwork passed away last year on April 17, 2014. We can only speculate, but possibly Ruffwork’s Apple Developer Membership has expired and this would caused the PCTHYOH app to no longer be available on the iTunes store. The PCTHYOH app should continue to function for hikers who have it installed on iPhones and it appears to still be available on the Android Google Play Store.

Hikers looking for another way to view Halfmile maps on smartphones can use any .pdf reader app, such as Adobe Reader. Here are step by step instructions:

Acrobat Reader in Apple iTunes store

Adobe Reader in Apple iTunes app store.

1) Start the App Store app on your iPhone and search for Adobe Reader. Install the Adobe Reader app.

Finding a Halfmile map using the Safari app.

Finding a Halfmile map using the Safari app.

2) Launch the Safari app on your iphone and navigate to https://www.pctmap.net/maps-url-loading/ The .pdf map files on this web page are optimized for viewing on smartphones and are not compressed .zip files that would require a special app to uncompress them.

3) Select a link to a map section and the map will load into Safari. You can view Halfmile maps in Safari, but only when you have a cellular or wi-fi internet connection.

Using Safari to Open a Halfmile .pdf file in another iphone app.

Using Safari to view a Halfmile .pdf file in another iphone app. Note the “Open in…” option that appears after tapping the map.

4) Tap the map in Safari app and note the “Open in…” option.

Apps available to open .pdf files will vary depending on what apps are installed on your iphone.

Apps available to open .pdf files will vary depending on what apps are installed on your iphone.

5) When you select “Open in…” you will find the option to open the Halfmile .pdf map with any iPhone apps that support .pdf files. Select “Open in Adobe Reader.”

Viewing a Halfmile Map in Acrobat Reader.

Viewing a Halfmile Map in Adobe Reader.

6) The Halfmile .pdf map will be opened in Adobe Reader and stored for offline viewing.

7) Repeat the steps for each map section you want to download to your smartphone.

A library of Halfmile Maps available for offline viewing from the Acrobat Reader Documents menu.

A library of Halfmile Maps available for offline viewing from the Adobe Reader Documents menu.

8) You can see all the stored .pdf files in the Adobe Reader Documents menu option.

It’s best to load maps in Adobe Reader when you have a wi-fi internet connection or a strong LTE cellular signal.

Adobe Reader is a very useful app for hikers that will store and view any .pdf file such as Halfmile Maps, the PCT Water Report (use the links to .pdf format not .html format), bus schedules, instructions manuals, and many other documents.

Halfmile Smartphone Apps Updated for 2015

The Halfmile PCT app on an iPhone.

The Halfmile PCT app on an iPhone.

Halfmile Pacific Crest Trail iPhone and Android smartphone apps have been updated for the 2015 hiking season.

Halfmile PCT apps are a companion to Halfmile’s 2015 printed map set to aid navigation. The app determines your location and, if on the PCT or one of its side trails, it calculates trail distances to over 3,000 PCT landmarks and displays any relevant trail notes. The app also calculates elevation gains and losses to landmarks and compass bearings and distance to landmarks. The IOS app includes a live trail diagram to aid navigation.

Halfmile apps do not contain maps of the Pacific Crest Trail — think of them as a very accurate, location aware, digital PCT Data Book.

Changes for 2015 include:

  • The app data is now synchronized with the official 2015 Halfmile maps and GPS data.
  • Over 1000 new PCT landmarks have been added for locations such as water sources, trail junctions, campsites, road crossings, etc.
  • Over 90% of the PCT track data has been replaced using much higher accuracy sources than before.
  • Compatibility with new smartphones and new operating systems.
  • Various small fixes and enhancements have been made to improve readability.
  • The Halfmile PCT app is available free at the iTunes Apps Store or Google Play.

    Since Halfmile’s PCT mileage estimates have changed for 2015, be sure not to mix and match 2014 and 2015 versions of PCT maps, apps, or GPS data.

    Check Out the New Elevation Profiles!


    Halfmile’s Pacific Crest Trail maps have been updated for 2015 and they include cool new elevation profiles created by programmer Tom “66” Reid.

    Colors used on FAA charts.

    Colors used on FAA charts.

    The new elevation profiles feature color coding in the style of FAA Aeronautical Charts, improved formatting to show more waypoints, and mileage that matches the 2015 Halfmile PCT mileage estimates.

    Information on the elevation profiles includes:

    • Page numbers to identify which PCT map pages are covered.
    • Black dots for every half mile of trail.
    • Red dots marking individual waypoints along the PCT.
    • PCT mileage from the Mexican border every two miles.
    • Elevation gain/loss is estimated (see the red circle above) for every two mile section of PCT.

    The new elevation profiles are included with each section of PCT maps, or just the new elevation profiles for California can be downloaded here, or Oregon/Washington profiles can be downloaded here. Since PCT mileage estimates have changed for 2015, be sure not to mix and match 2014 and 2015 version of PCT maps, apps, or GPS data.

    Waypoint Abbreviations



    We have been asked by several hikers about the abbreviations used for waypoint names on Halfmile Project PCT maps, apps, GPS data, and Google Earth files. Here is a list of the most common abbreviations:

    BB — Bear box or bear locker (mostly in the Sierra)
    CG — Campground
    CS — Campsite
    GT — Gate
    JMT — John Muir Trail
    Hwy — Highway crossing
    NF — National Forest boundary
    TH — Trailhead
    TR — Trail
    PL — Powerline
    PO — Post Office
    RD — Road crossings
    RR — Railroad track
    Ski — Ski lift
    Wild — Wilderness boundary
    WA — Possible water source (not on www.pctwater.com, mostly north of mile 700)
    WR — Possible water source listed in the PCT Water Report at www.pctwater.com
    WACS — Possible water source and campsite
    WRCS — Possible water source from the Water Report and campsite

    Curious which waypoint types are most commonly used? Here is a list from the new 2015 Halfmile Project data:

    3161 — total number of 2015 waypoints
    972 — WA waypoints
    745 — CS waypoints
    498 — TR waypoints
    466 — RD waypoints
    152 — WR waypoints
    73 — GT waypoints
    61 — Hwy waypoints
    54 — PL waypoints
    33 — Wild waypoints
    21 — CG waypoints
    16 — BB waypoints
    12 — TH waypoints
    8 — PO waypoints
    6 — NF waypoints
    6 — Ski waypoints

    About the 2015 Halfmile Updates

    Updating maps for 2015

    Updating maps for 2015

    The 2015 Pacific Crest Trail hiking season is rapidly approaching and understandably we have been getting questions about what’s changing in the 2015 edition of Halfmile’s PCT maps and when new maps, apps and GPS data will be ready.

    2014 was a massive data collection effort for the Halfmile Project team. Halfmile and Dirt Stew thru-hiked the PCT (Halfmile northbound, Dirt Stew southbound) carrying very accurate custom GPS devices designed for mapping long hiking trails. 8,296,179 new data sample points and 5,065 new waypoints were collected.

    GPS reception can be challenging along some parts of the PCT due to tree cover or terrain such as mountains or canyons that sometimes block GPS signals. This is especially true in Oregon and Washington. The custom GPS logging hardware performed amazingly well because of the outstanding performance of the ublox NEO-7P GPS module, external mast mounted antennas, and the merging of multiple GPS data sets using software developed by David Lippke. We are confidant this is the most accurate data ever collected of the PCT.

    Overall the new 2015 data has an average horizontal accuracy of 1.9 meters. Here is the horizontal accuracy by PCT section:

    CA Sec A: 0.67 meters
    CA Sec B: 1.26 meters
    CA Sec C: 1.11 meters
    CA Sec D: 1.19 meters
    CA Sec E: 0.81 meters
    CA Sec F: 0.98 meters
    CA Sec G: 1.18 meters
    CA Sec H: 1.44 meters
    CA Sec I: 1.62 meters
    CA Sec J: 1.51 meters
    CA Sec K: 1.61 meters
    CA Sec L: 0.49 meters
    CA Sec M: 0.57 meters
    CA Sec N: 0.46 meters
    CA Sec O: 0.68 meters
    CA Sec P: 1.92 meters
    CA Sec Q: 2.37 meters
    CA Sec R: 2.19 meters
    OR Sec B: 2.66 meters
    OR Sec C: 2.49 meters
    OR Sec D: 2.57 meters
    OR Sec E: 2.32 meters
    OR Sec F: 2.45 meters
    OR Sec G: 3.78 meters
    WA Sec H: 3.45 meters
    WA Sec I: 2.94 meters
    WA Sec J: 1.75 meters
    WA Sec K: 3.34 meters
    WA Sec L: 2.42 meters
    Continue reading

    Halfmile’s Smartphone Apps Updated

    The Halfmile’s Pacific Crest Trail apps for both iPhones and Android smartphone have recently been updated. The apps are available free from Apple’s iTunes Store or Google Play.

    The updated Halfmile Android app includes 2014 data and minor bug fixes.

    The updated Halfmile Android app includes 2014 Halfmile data and minor bug fixes.

    The iPhone Halmile app includes a cool new Trail Diagram mode, simplified user interface, and the latest 2014 Halfmile data.

    The iPhone Halmile app includes a cool new Trail Diagram mode.

    The updated iPhone app includes a cool new “Trail Diagram” mode, simplified user interface, and the latest 2014 Halfmile data.

    The updated Android app includes the latest 2014 Halfmile data and Minor bug fixes.

    Both apps are designed to be a companion to Halfmile’s Pacific Crest Trail printed map set to aid navigation on the PCT. The app determines your location and, if on the PCT or one of its side trails, it calculates trail distances to 1,700 PCT landmarks and presents any trail notes relevant for the location.

    Features of both apps include:

    • Simulation mode for hike planning and hiker support
    • Provides specific “how to walk there” instructions for all points
    • Live trail diagram with optional compass orientation
    • Calculates cumulative elevation gains and losses to all points
    • Powerful search function for features like water sources, campsites, and resupply locations
    • Calculates which printed map pages contain your location
    • Works without cell phone service
    • Download and Go — no extra configuration or data needed

    Elevation Gain on the Pacific Crest Trail

    elevation profiles

    Halfmile’s PCT Map elevation profiles.

    Pacific Crest Trail hikers are often interested in knowing the elevation gained or lost as they hike along the Pacific Crest Trail. The 2014 Halfmile Project estimates the total elevation gain/lost for a northbound thru-hiker is 489,418 feet of climbing and 488,411 feet descending with an overall change of 1,007 feet as they hike from Campo to Manning Park.

    Here is a breakdown of elevation gain/loss by PCT section:

    Gain Loss Change
    CA_Sec_A 16,452 -16,335 117
    CA_Sec_B 19,006 -20,698 -1,692
    CA_Sec_C 22,427 -20,775 1,652
    CA_Sec_D 26,944 -27,403 -459
    CA_Sec_E 21,200 -19,894 1,306
    CA_Sec_F 14,891 -13,469 1,422
    CA_Sec_G 23,576 -18,061 5,515
    CA_Sec_H 32,804 -34,987 -2,183
    CA_Sec_I 14,320 -13,257 1,063
    CA_Sec_J 14,049 -16,282 -2,233
    CA_Sec_K 10,661 -10,887 -226
    CA_Sec_L 5,282 -7,893 -2,612
    CA_Sec_M 18,095 -20,421 -2,326
    CA_Sec_N 17,106 -16,424 682
    CA_Sec_O 17,961 -18,747 -785
    CA_Sec_P 19,147 -15,326 3,821
    CA_Sec_Q 9,311 -13,918 -4,608
    CA_Sec_R 14,290 -11,390 2,900
    OR_Sec_B 8,124 -7,427 697
    OR_Sec_C 9,008 -8,056 951
    OR_Sec_D 7,588 -8,422 -834
    OR_Sec_E 9,614 -9,394 220
    OR_Sec_F 15,476 -16,619 -1,144
    OR_Sec_G 8,965 -12,924 -3,958
    WA_Sec_H 29,552 -25,348 4,204
    WA_Sec_I 18,327 -19,744 -1,417
    WA_Sec_J 18,773 -17,711 1,062
    WA_Sec_K 31,441 -30,641 799
    WA_Sec_L 15,030 -15,958 -928
    Total 489,418 488,411 1,007

    It turns out that estimating elevation gain/loss is a surprisingly complex and technical process. The Halfmile Project has put a great deal of effort into this, and our estimates are much more accurate than, say, the ones that Google Earth produces, or any other source of PCT information.

    Elevation values obtained from GPS units are much too noisy for use in gain/loss calculations — even from the survey grade equipment that we now are using on the Halfmile Project. Instead, elevation data is based on USGS 1/3 arc second DEM (Digital Elevation Model) data.

    Halfmile Project gain/loss estimates use approximately 3/4 million GPS sample points along the Pacific Crest Trail. The elevation for each sample points is calculated based on a grid of 525 USGS 1/3 arc second DEM rectangles that surround the point. A two dimensional spline interpolation is then generated using the DEM rectangles to calculate the exact elevation of each sample point.

    elevation spline plot

    Blue lines are the elevation spline plots calculated based on 525 USGS DEM elevation rectangles. The center of each DEM rectangle is marked with a black dot. The elevation of a GPS sample point is then calculated, in this example as 1,252.04 meters. The process is repeated about 3/4 million times.

    Observant (or obsessed) readers may have noticed that the Halfmile Project elevation estimates changed slightly from 2013 to 2014. This year’s total elevation gain of 489,418 feet is slightly less than the 492,871 foot estimate last year. The reason for the changes are:

    • The DEM data itself is constantly being updated and improved by the USGS.
    • In some sections of the PCT we completely replaced the data with more accurate GPS data.
    • In all sections we changed our selection of points (i.e., doing a bit smarter job this year).
    • Last year’s interpolation was from a grid of 36 surrounding points and this year 525 grid points were used.

    While these changes are very small, even small changes add up over thousands of points.

    One reason we put so much effort into elevation calculations, is so that the elevation gain/loss estimates match between the printed maps and smart phone apps. The Halfmile smartphone apps calculate very accurate elevation gain/loss estimates between your current on-trail location and any landmark along the trail.

    Here the Halfmile smartphone app estimates an elevation gain of 7,102 feet and a loss of 4,047 feet from the Southern Terminus to the water fountain on Mt Laguna near Burn Rancheria Campground.

    The Halfmile smartphone app estimates an elevation gain of 7,102 feet and a loss of 4,047 feet along the Pacific Crest Trail from the Southern Terminus to the water fountain near the Burn Rancheria Campground.

    If you want even more details about Halfmile Project elevation estimates, David Lippke AKA White Jeep posted a detailed summary recently on the PCT-L. Here is a copy of what he posted:

    Hi, Lon alerted me regarding the PCT elevation gain/loss stats conversation here and so I thought some direct information might help. I’m the author and maintainer of the Halfmile apps and I generated all the elevation data and gain/loss numbers published for the last three annual cycles. I spend most of my time working on improving both the horizontal and vertical accuracy of all our PCT data. This effort has ballooned over the last couple years involving more than just myself and Halfmile with the deployment of survey grade equipment to the trail, custom GPS logging devices, and now further generations of all that we are scrambling to deploy for the 2014 season.

    Anyway, people often wonder how we calculate elevation gain and loss numbers along the PCT. It turns out that this is a surprisingly complex and technical process. The net is that we currently generate profiles that are much more accurate than, say, the ones that Google Earth produces. That said, there is still substantial room for improvement and we are working on that.

    The technical TLDR is that our point elevation values are produced by heavily processing USGS DEM 1/3 arc second data. Our gain / loss calculations then operate over this set using a smoothing factor consistent with the average error present in the DEM data and the average horizontal “side to side” path jitter observed along side slopes.

    Most will want to stop reading here. 100% tech talk follows. You have been warned. 🙂

    Going on in more detail, the process does not involve using GPS elevation data at all. As noted by Brick, elevation values obtained from GPS units are much too noisy for use in gain and loss calculations — even from the survey grade equipment that we now use. Instead, our raw source for elevation data is the USGS 1/3 arc second DEM (Digital Elevation Model) which provides average elevation values over rectangles that are approximately 8×10 meters on a side (the “8” varies with latitude).

    We start with our best filtered GPS horizontal data for each bit of trail. This ranges in horizontal accuracy from 1/2 meter (California sections L through O) to 3-5 meter accuracy (e.g., WA J) to unknown accuracy data that we hand select from the competing data sets. Over 2014 for the 2015 update, we hope to bring the average horizontal accuracy for the entire PCT to the vicinity of a single meter.

    Then we translate all those horizontal points to the horizontal datum used by the USGS and we fetch the DEM elevation values needed generate a grid of 525 points surrounding each subject point. Using those 525 points, we generate a two dimensional spline interpolation and query it at the exact point. This process is repeated for all 3/4 million horizontal data points and involves almost 11 million unique 1/3 arc second DEM values.

    So at this point in the process we have the best possible estimate for the elevation of each track point and way point expressed in terms of the NAVD88 vertical datum (quasi MSL) with the primary error sources being that of the USGS DEM (RMSE ~2.5 meters) and that of our collected horizontal positions.

    In the next step, we reduce the horizontal point count so that all sections stay within Garmin’s 10K track point limit. We do this by applying the Ramer-Douglas-Peucker algorithm with a 1.9 meter sigma overall and, in more accurate sections, a 1.25 meter sigma. In other words, when the trail is going along a straight road or the aquaduct, the points can be several hundred meters apart but in tight turns they may only be a couple meters apart.

    Finally, to calculate gains and losses between points, a tally is kept from track point to track point except that no gain or loss is recorded until a track point is reached that has an elevation loss or gain more than 5 meters from the starting track point. When that occurs, the algorithm moves forward to the current end track point and picks up the counting again. When reporting the gain / loss to a particular way point, any residual in the smoothing is closed out so that the numbers all “add up”. As a side note, this creates a small numerical issue when one decides to total our published per-section numbers over the whole trail and compare those to the whole trail numbers in the (soon to be released) 2014 version of the Halfmile apps — our per-section numbers are “closed out” with respect to this 5 meter smoothing but the app just keeps rolling through the boundaries.

    Sorry for the tech talk, but I just wanted to address all the speculation about what feeds into these calculations. Questions are always welcome and so is project involvement — we have all manner of “task” available for the inclined. 🙂

    All the best,
    David Lippke aka White Jeep