Table of Contents
- Devices and Technological
- Google Earth Paths
This is an endless post. I will modify it.
Devices and Technological
Garmin Edge 130 elevations
My Garmin Edge 130 is an “entry level” GPS device with a barometric altimeter. That model is no longer on the market. A small head unit with a barometer is at and entry level price is a bargain. It has some other entry level product issues. The software was written several years ago, and has many glitches. Riders complained in forums, which resulted in Garmin closing discussion on some complaints and issues. I will review it some other time.
The Garmin Edge 130 has data fields that allow a rider to display elevation, distance ascended, distance descended and grade. The manual says the “grade” data field displays:
“The calculation of rise (elevation) over run (distance). For example, if for every 3 m (10 ft.) you climb you travel 60 m (200 ft.), the grade is 5%”.
The barometer appears to read the surface elevation from point to point. It does not. The elevation field displays disparate readings for the same location on different rides depending on wind and the location of cells of high pressure. The calculations of total elevation gained or total descents vary for the same ride on different days. The software returns data sampled a few seconds and many meters earlier in the ride.
Garmin seems to correlate location data with elevation data from some maps. The head unit seems to supply a starting elevation for rides starting at known points. Information on how Garmin gets this data and programs the head units is proprietary.
Trying to read the device display is a distraction. Using Garmin programs and apps – for instance reviewing a ride track in Garmin Connect to get an elevation for a particular point on a trip is slow. Garmin Connect uses map data from Garmin’s “OpenStreetMaps” and displays a track on a map. It seems possible to place a cursor on a location and get the elevation. It was not a useful exercise.
Google Earth Pro
The Google Earth Pro app, in Windows, on a desktop computer, can show location and elevation if you went to use the “Ruler” tool to draw a “path”. Google Earth will calculate and display “slope”, a % of distance along a path (“grade” in the language of Garmin).
It seems to be very precise, but precision depends on matching maps and aerial photos to satellite and drone data for the devices and systems used to record the elevation of specific locations on the surface of the eath as map coordinates. It also depends on how screen magnification and the plotting of a path affect the way the program identifies map coordinates and retrieves the recorded elevation.
Smart Phone Apps (Android)
Several Android smartphone apps can locate the phone as a place on a map and provide an elevation. They vary in accuracy depending on factors involving the use of the smartphone sensors and the network connection including the cell phone network.
Any given elevation or altitude app may need device permissions to use a device’s location services. Some use cellular data. Some share data with third parties and decline to delete data. Many apps do not provide ride tracks to riders.
I used the Android App My Elevation by RDH software. It is I stop and log readings in a notes-taking App. I only do that occasionally. I can draw a section in Google Earth with the ruler tool, which I do very occasionally.
Raw elevation data in the table is the elevation in meters, above mean sea level according to the smartphone. It sometimes varies from Google Earth Pro.
|Crossing or Point||Elevation|
|E&N||View Royal Boundary|
(S end of Hallowell)
|Esq.||E&N||CFB, Graving Dock entrance,|
Admirals Road at Colville
(high point in W. Esq. is 64 m.)
Notes in narrative above.
|Esq.||Esq. Rd.||Civic offices, library|
W of Fraser Avenue
|Goose||1 Km Sign|
end of Harbour, beginning of
trail along the harbour
|Cordova Bay Rd|
E end of Cedar Hill X
|VR||Goose||Ridge West of West Tunnel, |
Helmcken; near Victoria General
|Saan.||Goose||Overpass of MacKenzie|
along Douglas (Highway 1)
|Saan.||Lochside||Near 3 Km. post|
Rest stop, Don Mann
|Saan.||Lochside||Royal Oak Drive|
at Lochside School
|Saan.||Lochside||Near 9 Km. post|
Cordova Bay Road
Google Earth Paths
The elevation of the junction of Rockheights Avenue at Highrock Avenue is in the table above, I can draw a path in Google Earth from the E&N trail, along Hutchison and Rockheights to the intersection of Rockheights. The path is 514 meters long, from the low point of 17 m. above mean sea level on the E&N trail to a high point of 43 m., with a drop to 37 m. at the measurement point. The gain to the high point is 27 m. The average slope is 6.5 % . The slope goes to over 10% where Hutchison crosses Lockley. The slope goes from 10% to 15% for 150 meters. The slope gets shallower at Rockheights, but the climbing continues. The smaller chain ring on 2x drive trail system is useful.
This route on side streets, is preferable to sharing the road with the heavy traffic on Admirals Road on the climb from Woodway to Esquimalt Road (average slope 4% over a distance of 350 m., with a 150 m section with slopes of 10% to 15.5%).
Avoiding these climbs to travel from Local CRD3 in NW Esquimalt to the libary on Esquimalt Rd. in SW Esquimalt means riding north on the E&N trail to a street that crosses Esquimalt Rd and gives access to the EW streets in the West Bay area.