So when I was planning the South Coast and Cape trip with Galen, based on map.greenway.org it was about 150 miles. By the time we were all said and done, we had biked about 198 miles. There was like 2 miles on either end of the trip for me in Portland to/from the train station, a bike between North and South Station in Boston, a bit of biking in Providence, and a little bit extra in Provincetown….but I don’t think all of that adds up to anywhere close to 40+ extra miles from the main part of our trip.
Galen and I both thought it was weird that it ended up being so much longer than we had anticipated, especially given that I had used map.greenway.org to plan our trip. I told him I would do another search on map.greenway.org after our trip and see if there was still a big discrepancy. I just did the search gain and it came up with 155 miles.
I’m wondering if something is off with map.greenway.org given the 40 mile or so difference. I used a trip computer to log the mileage on the trip and I restarted it just as I left my old apartment in Portland on the first day. I don’t mean to send you on a wild goose chase, I just wanted to put it out there as something I noticed…
That's not exactly the same route, but it's close!
So much has to do with the precision of the road geometry and of course any backtracking or side trips the rider might take, though hard to believe those account for a 20% difference in mileage.
So I don't think the issue is our code but hard to know. Two potential other causes:
Areas where less precise linework in the routing system don't account for switchbacks and the like, hard to imagine at this scale but maybe possible. A quick visual of the route didn't seem like it should vary that much.
The user's cycle computer could be miscalibrated to the bike or something?
Perhaps an ECG staffer with a known-good cycle computer could do a stretch of route somewhere and compare against trip planner.
User report via @nilesbarnes :
The search: https://map.greenway.org/?loc=10,41.79998,-70.45601&route=41.82318,-71.41226,42.05706,-70.17782
A similar route in the debugger: https://router.greenway.org/debugger/?x=-71.406326&y=41.824485&z=14&testmode=production&slat=41.822732&slng=-71.411345&tlat=42.048230&tlng=-70.181010
Here's a very similar route in gMaps at 136mi.
That's not exactly the same route, but it's close!
So much has to do with the precision of the road geometry and of course any backtracking or side trips the rider might take, though hard to believe those account for a 20% difference in mileage.
Here's a nice test of basic accuracy of a single simple stretch of road, the west side of Manhattan: https://router.greenway.org/debugger/?x=-73.952065&y=40.768582&z=12&testmode=production&slat=40.718191&slng=-74.013071&tlat=40.846023&tlng=-73.946014 9.8 miles
And then the precise same route in Google Maps: https://www.google.com/maps/dir/'40.718191,-74.013071'/'40.846023,-73.946014'/@40.7820648,-74.0499133,12z/data=!3m1!4b1!4m10!4m9!1m3!2m2!1d-74.013071!2d40.718191!1m3!2m2!1d-73.946014!2d40.846023!3e1 Also 9.8 miles.
So I don't think the issue is our code but hard to know. Two potential other causes:
Perhaps an ECG staffer with a known-good cycle computer could do a stretch of route somewhere and compare against trip planner.