## Friday, August 22, 2014

### Answer: The shortest--and flattest--route there.

I asked two simple routing questions that takes a bit of figuring to get an answer:

In both cases, there are two obvious routes from Point A to Point B.  The question is simple:  Which route is flatter?  (To be precise, find a route with the smallest elevation gain.)

1.  Suppose I'm in the Southwest of the US and want to do a bike ride from Farmington, New Mexico, to Durango, Colorado.  What route would you recommend for the least overall elevation gain between the two cities?
2.  Suppose that a few months later I'm in the Southeast of France and want to ride my bike from Echirolles (France) to Oulx (Italy). What route would you recommend for the least elevation gain between these two cities?

As several sharp-eyed readers pointed out, Google Maps just recently announced a bike route elevation tool to help answer exactly this question.  (Google's announcement; TechCrunch; ...)

You can compute bicycle elevation profiles (currently) in all the 14 countries Google offers biking directions. (Austria, Australia, Belgium, Canada, Switzerland, Germany, Denmark, Finland, Great Britain, Netherlands, Norway, New Zealand, Sweden, US)  Unfortunately, France and Italy aren't included...

So to solve the first Challenge, the easiest thing to do is just use Google Maps, use "Find Directions" and then select the Bicycle Route option.

Here I've just asked for the bike route from Farmington, NM to Durango, CO.  It's a lovely ride, almost 52 miles long, with an elevation gain of 1,588 feet.

There's another obvious route that would leave Farmington on 170/140/160 to Durango.

To see the elevation profile for that route, I just drag the route from where it is (by pressing-and-holding on one of the small circular "control points" on the line) to where I'd like it to go:

Once I've moved it to Route 170, the map looks like this:

This route, by contrast, is a bit shorter but has a bit more climbing in it (2,444 ft vs. 1,588 ft).

But as Ramón pointed out in his link to the "Climb = what flat distance" article, there are often many factors to take into account when computing route relative difficulty.  This is a fascinating discussion, but since I want to ride this route anyway, I'm just going to pick the route that has the least elevation gain.  (Side note:  That article is written by cyclists in Florida, one of the world's flattest states, where, I suppose, they worry about things like this!)

Of course, there are other tools you can use to compute the same kind of information.  In the comments, Rosemary points to the routes she explored using Strava, the athletic tracking and mapping system.  Here's one of her maps for the Farmington-to-Durango trip:

 Strava map by Rosemary
It's important to recognize that there ARE multiple tools to figure out this kind of information, each with its own capabilities.  In the Strava app you can sweep your mouse over the elevation profile at the bottom and read off the elevation and grade.  As you move the mouse, the blue dot follows along on the map just above it.  (This is true for Google Maps as well--move the mouse along the profile and see where the dot is on the route.  But Maps doesn't show the elevation or grade at that location.)

Answer to route 1:  I'm going to stick with the first route (550/160).  It's a little less climbing.  And spot-checking the Streetviews along the route suggests that the road has nice shoulders, not a lot of traffic, and nice views.

Question 2:  Echirolles (France) to Oulx (Italy)  We already know that Google Bicycle Routes won't work there?  What to do?

Answer:  Find another tool to do the same kind of work.  I liked Ramón's query to find such tools

[ cycling routes elevation comparison ]

this set of results leads to many tools for doing this kind of analysis.  For my profiling, I happened to use Veloroutes.org (but others work as well).  Here's the profile for the obvious southern route from Echirolles to Oulx:

AND... If you click on the "get elevation image" (upper right of the blue box), you'll see just the elevation of the route selected.

And I note that this route is 123.6 km long, with 3262 m gain, with a max grade of 30%.  (That's a HUGE grade! And there are two big hills.)

Here, for contrast, is Rosemary's Strava map of the same route:

Interestingly, this map shows a max grade of 17.1% (which is much less than the 30% I saw on my map). Since neither mapping service tells how they measure grade, it's hard to know which is more accurate--but all cases, this is a steep route.

When I did the same plot for the other (northern route), I get this map:

This route is 155.3 km, with 2837 m gain, with a max grade of 20%.  (That's still a big grade, but much better than 30%.)

Here's the elevation profile for the northern route.

Ramón also found a different bike route elevation site (PerfildeRuta) that does very much the same thing (also available in English).  Here's their diagram of this route.  Note that they believe the maximum grade on this route is 47%!  (Really?  That's not a grade--those are stairs!)

And if I now spot check the two routes, the southern route looks MUCH more appealing.  The northern route is mostly major highway, while most of the southern route looks like this...

So.  Summary:

Southern: 123.6 km long, with 3262 m gain, with a max grade of 30%.
Northern:  155.3 km, with 2837 m gain, with a max grade of 20%.

It's clear that the Northern route is flatter, albeit slightly longer.

BUT the Southern route is very appealing.  And as Rosemary points out, it goes right next to the Alp d'Huez, one of bicycling's most revered roads for its dramatic races throughout the history of the Tour de France.

If I was to do this ride, I'd definitely go the Southern route.  Longer, steeper, but MUCH more appealing.

Search Lessons

(1) Always keep up-to-date on announcement about new search capabilities.  While people have always created elevation profiles, it's much easier if you know about the tool that does exactly that.

(2) When using a new UI (such as that in the VeloRoute elevation profiler), pay attention to options that might not be well-marked.  The "get elevation image" is exactly what I wanted from this map, but it's a pretty hidden function.

(3) Keep tracking of an evolving question.  Even when the person asking the question says "I want the flatter route," the process of learning about the question often reveals information that overrides the initial criteria.  This kind of thing happens all the time in real research questions.  You start with question A, but in the process of research you discover additional information that changes the question into B, then maybe question C... This is the nature of research, and definitely of search.

Which is why we do SearchResearch; it's a fascinating way to learn more about the world at large.

And now I need to go for a bike ride.  Thanks to everyone who wrote it on the comments.  Keep 'em coming.

Search on!

1. This challenge had me looking into the variations one can find on elevation profiles as you mentioned. Smartphone GPS and Garmin GPS work on two different systems. I know there is difference (?) how the GPS works so I will take my Garmin Oregon on my next ride to compare results to Strava. As well I carry a personal locator, Spot, which tracks my routes via GPS so my whereabouts is always available at home. I'm going to compare all three to see what results I get. Of course this challenge was great fun being a cyclist. Will you add an addendum about the historic interest?

2. This comment has been removed by the author.

3. Good Day, Dr. Russell and everyone.

I learned a lot about cycling with this challenge. When doing the searches found Veloroutes. There the problem I found is that couldn't see 2 or more options compared like I saw in Google Maps. Therefore, searched for another site. My question is how a cycling route is made in the maps or apps? I mean in Perfil de Ruta, for example, they created a route that is almost a straight line from point to point and I am sure that option most times is impossible. So, how they now a bicycle can go through that route?

Have an amazing weekend everyone. Dr. Russell, enjoy your ride.

1. Excellent question Ramón. I will give you my experience which may help. Using a GPS device (not phone) I often would setup a ¨route¨ which consisted of the least amount of points. It was just to give me a general idea of where I was going. However ¨tracking¨ was done on the road/trail & before I set out, I could set up how I wanted the tracking done. It would be (going from memory right now) based on time or distance or elevation (I think & maybe probably more methods). So if I wanted to track my trip I would choose which method & how often I wanted a point created. The more points the more data created in my tracking & the smoother the lines & of course the more points the more accuracy. However it literally could create thousands of points.
Getting back to routes since they are used as a guide only it may be that some apps minimize the number of points which of course create straighter lines & less accurate data.
Tracking is I think generally used by most for detailed data of the individuals actual experience so they can track performance.
I can't run Perfil de Ruta on my chromebook so I can't see if you have any control. Most apps seem to allow you to create your own points but who is going to create a track with 5000 points, not likely. Think of routes as what you use in the planning stage and tracks as a review of what you did. However Google Maps and these apps allow you to track your trip & I suspect that in the last few years they have become much more capable of giving realistic tracking data. I am going to test this out with 3 actually 4 devices on my next ride. I have a GPS device, smartphone, Spot tracker & bike computer. It will be interesting to see what results I get.

2. Thanks Rosemary. It is very interesting. Please let us know how your tests work.

Have a nice day!

4. I did a 10 km test ride.

Garmin Oregon- Track had 238 points (default setting). Now each of these points provides me with a row of data such as coordinates, distance & time between each point, compass bearing and elevation. That is how tracking data is collected.

Elevation is a whole different matter. My Garmin data was totally inaccurate. There are two climbs max grade #1 hill is 7.3% & #2 hill is 9.6%. On the Garmin it almost shows no change in elevation. Why? The Garmin has more sophisticated features that understood when I set it up but have forgotten how to set some of them. It was set for Barometric Pressure and variable elevation. I was going to go into more detail but thats getting too detailed. Its suffice to say my Garmin gave false readings because it was set up wrong. That’s the benefit of just turning on Strave or MapMyRide & let them work out variables.

However the Strava app on my Android & Bike computer(Garmin) had almost identical data. So they are likely using the same type of elevation data gathering method/data base. How do they do that?
Here is a quote from Strava...

¨Strava detects devices with barometric altimeters and recognizes the data from that source. Since elevation data derived from a GPS signal is fairly inaccurate, Strava automatically corrects elevation derived from a GPS source by consulting elevation databases to determine the elevation at each point in the activity.
How Altitude data is collected:
Barometric altimeters determine altitude by measuring atmospheric pressure. Measurements can be affected by changes in the weather or the sensor holes getting blocked by water or other debris. Device manufacturers may provide basic calibration procedures. For example, Garmin devices with barometric altimeters allow a certain number of manual elevation points to be set; starting an activity near an elevation point causes the device to use the known elevation as the starting point. Consult the manual for your device to learn about calibration procedures.
GPS altitude measurements are derived from GPS signals and can have relatively high vertical error. They also depend on how many satellites are being used and where the satellites are located in the sky.¨
They confirm my mistake on my Garmin, first I didn't calibrate it before I began & some settings were off.

Map my Ride says ¨Our app sources this data using information from the United States Geological Survey...We still cross-reference with the USGS data, but it could result in differing elevation stats.
Veloroutes says this “the USGS service is great, and free, but sometimes flaky. sometimes their web-services just return zero for all coordinates. check here to see their system status. (NOTE: veloroutes.org also uses a backup web-service if the USGS is down, but earthools.org is less accurate).
Here is the link to the USGS data mentioned http://nationalmap.gov/viewer.html and another interesting site http://www.earthtools.org/
I didn’t find one for Perfil de Ruta that you used.
So it I think it comes down to using the data provided within an app but knowing its limitations. If doing some serious riding or hiking where elevation matters do some research on these two websites. When it gives wacky numbers like 47% grade you will then want to check out resources such as other apps, other websites or other devices.

One more thing, Spot which is designed as a tool for locating and rescuing doesn’t use tracks but rather waypoints. So in my case it created a waypoint every 10 minutes showing time and coordinates which are uploaded to the website for viewing at home, anyone you wish to share with & are available in case of emergency in the database out of Houston, Texas. Should I hit the red button Houston notifies the local authorities and that can be anywhere in the world.

I hope this gives you some insight into how these tools work.