[lugao]

I made a comment earlier that was rightly flagged for its tone, and I would like to restate the technical point more constructively.

The post author, Dan Piponi, clearly knows about fractals, but his post raises the question of whether asking Fermi questions in interviews is actually effective. I am skeptical that such questions would have prevented this type of bug.

I suspect the issue stems from small measurement imprecisions accruing over long distances, which is—in my view—tied to the fractal nature of roads traversing natural landscapes.

However, as others have pointed out, it may also be tied to road closures: if closed segments are set to a higher length internally (to discourage routing), these values might be getting summed up blindly over longer distances.

None of these issues would have been prevented by being good at estimating quantities alone.

Apologies again for the unconstructive tone of my previous comment.

[DanPiponi]

Here's a Fermi-ish question: given the fractal nature of typical landscape, should a truck driver budget for 10 times as much time as would be predicted by using the known typical speed of the truck and the distance as the crow flies?

(Aside: the nearest grocery store to my house is 1 mile away but the shortest route by car, as measured by the car odometer, is 10 miles.)

[Lucasoato]

A pure spirit is required to admit your own mistake. Don’t be let down by an error, never lose the opportunity to fix it. May this be of example to everyone to keep improving this already wonderful but not perfect community.