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Incorrect distance using mapping feature (Read 644 times)

    mapped a run in Boston yest. at  7.3 miles using the mapping feature.  Finished the run in slightly under an hour.  Since that did not seem right for the pace I was running, I remeasured it using the map on soundkeepers... it came out to 6.3 miles, which seems about right.  Is this map normally innacurate in cities?

      jaybar,

      Without seeing the map, I cannot tell you if the map is indeed wrong.  I made a map of the Boston Marathon recently and got 26.27 miles so I know it is accurate.

      Stacks


        Have you had a careful look at your map?  Sometimes a misplaced click, or a strange detour occurring when you have "follow-the-road/path" feature can add distance to the map without your being aware of it.

          I agree it seemed weird.  I use the map almost every day and have for years and I never noticed this before.  I could go click through it again, but I did it once yesterday before the run and again this morning when i went to log it. The same each time.  At first I was excited that my pace was so quick for what seemed an easy run, the more I thought about it, however, i knew it should be wrong.     Maybe if I did it manually it would be different and correct.  Maybe there is just a bug when mapping a Boston run?

            Eric, i saved it in my courses under "Map for Eric."  Just did it, but the mileage this time was 6.8.  mapped  the same route on soundkeepers again just now and got the same 6.35.

              jaybar,

              It looks like you created the map with follow road option enabled.  I don't think Sound Keepers' map has this option, or at least I didn't see one so you must have mapped it out manually on their site.  There are many twists and turns in your map.  If you mapped out all the points manually, you'll likely smooth out the map and will end up with a short map.  I stand by the distance reported by my mapping software.

               

              eric Smile

                That is the glitch I guess.  the primary reason I rely on this map is to avoid having to do it manually. 

                 

                In Boston at least (where inputting manually is a pain), there are some detours using follow the road but they are inconsistently applied.  Using follow the road should have taken me underground through the big dig, with the resulting detours to the on ramps off ramps, but it took me along the surface, so I assumed it was not an issue. Looking back at a new map I just made, i see some detours in Charlestown (don't know where you are from Eric), that take me off the main drag (rutherford ave)  as well as some unwanted  detours at an intersection.  other unwanted vehicular detours on mem drive and  coming off the mass ave bridge   (instead of the pedestrian route), but I later cross the feidler pedestrian bridge and the common no problem. lesson learned.  Thanks.

                  That is the glitch I guess.  the primary reason I rely on this map is to avoid having to do it manually. 

                   

                  In Boston at least (where inputting manually is a pain), there are some detours using follow the road but they are inconsistently applied.  Using follow the road should have taken me underground through the big dig, with the resulting detours to the on ramps off ramps, but it took me along the surface, so I assumed it was not an issue. Looking back at a new map I just made, i see some detours in Charlestown (don't know where you are from Eric), that take me off the main drag (rutherford ave)  as well as some unwanted  detours at an intersection.  other unwanted vehicular detours on mem drive and  coming off the mass ave bridge   (instead of the pedestrian route), but I later cross the feidler pedestrian bridge and the common no problem. lesson learned.  Thanks.

                   

                  Get a Garmin with a foot pod and you will never have to measure a route again. I'm using a FR60 with foot pod and it seems to be recording the distances pretty accurately after calibration. The FR60 doesn't use GPS at all and is pretty cheap

                   

                  The pain that hurts the worse is the imagined pain. One of the most difficult arts of racing is learning to ignore the imagined pain and just live with the present pain (which is always bearable.) - Jeff

                   

                  2014 Goals:

                   

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                    Well if it isn't my favorite running lawyer, back from the dead.  Good to see you logging miles Jay, see you on a Tuesday night soon?

                    E.J.
                    Greater Lowell Road Runners
                    Cry havoc and let slip the dawgs of war!

                    May the road rise to meet you, may the wind be always at your back, may the sun shine warm upon your SPF30, may the rains fall soft upon your sweat-wicking hat, and until you hit the finish line may The Flying Spaghetti Monster hold you in the hollow of His Noodly Appendage.

                      I'm in the Boston area so I know the streets pretty well.  RA offers several modes: pedestrian, cycling, car and manual.  Pedestrian is the default mode, which is why it does not go into the tunnels and avoid highways.  With all the changes around town, Google may not have updated their routing data.  In those cases, switching to manual mode might be better.  You can change modes at any time during the mapping process.

                       

                      Most of the time, auto follow route in pedestrian mode is good enough.  But if I need the map to be as accurate as possible (e.g. official race routes), I plot the entire route manually using satellite view and zoomed all the way in.  I can usually get the distance error down to less than 1%.