Discussion:
Distance Terminology
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Pavel Svinchnik
2017-04-30 17:43:26 UTC
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Based on latitude and longitude, it's 617 miles from my house to my son's house by straight-line distance. When I do a driving distance check, it's 747 miles, because there isn't one perfectly straight highway connecting the two houses.

How would you determine the "efficiency" of the highways versus straight-line? If I divide driving miles versus straight line, I get 747/617 = 1.2107, so I could say that there's a travel excess of 21.07%,

On the other hand, 617/747 = 0.8260, so the straight line is 82.6% of the driving distance, so I could say that the road layout "inefficienty" is 100% - 82.6% = 17.4%.

Is one preferable to the other? Or is there a third method?


Paul
William Elliot
2017-05-01 02:20:06 UTC
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Post by Pavel Svinchnik
Based on latitude and longitude, it's 617 miles from my house to my
son's house by straight-line distance. When I do a driving distance
check, it's 747 miles, because there isn't one perfectly straight
highway connecting the two houses.
A straight line would be a cord.
A surface geodetic is an arc of great circle.
Post by Pavel Svinchnik
How would you determine the "efficiency" of the highways versus
straight-line? If I divide driving miles versus straight line, I get
747/617 = 1.2107, so I could say that there's a travel excess of
21.07%,
On the other hand, 617/747 = 0.8260, so the straight line is 82.6% of the driving distance, so I could say that the road layout "inefficienty" is 100% - 82.6% = 17.4%.
Is one preferable to the other? Or is there a third method?
Yes, the latter Yes, the efficiency of a road comparted to a real
straight line. Of interest is the efficiency of a geodetic to a
straight line. When the points are at polar opposites, the efficiency
is the lowest.

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