Why routing alogrithms from different maps don't always give the same route

A panorama view of Pielinen Lake in Koli, Finland.

When the snow comes, roads to Koli become treacherous. During winter, daylight is significantly reduced adding further difficulty to driving. For Koli, daylight lasts for just six hours in December.

Navigating to the national park becomes not just a matter of getting there on time, but a matter of getting there in one piece. In many cases, navigation systems don’t consider how dangerous roads can be in adverse weather and for inexperienced drivers when they suggest a specific route, putting drivers in unnecessary danger.

Earlier this week, Miika Mäkelä, who works in TomTom’s map sourcing team, came across an instance in Koli where a number of popular routing and navigation services were sending drivers down a particularly dangerous route instead of safer available alternatives.

“During winter it can be hard to access [Koli] due to poor roads in the area. The shortest [default] route in ideal situations will be the fastest, but in winter, the curvy unpaved road can be tricky to drive,” Mäkelä says.

As part of his role at TomTom, Mäkelä follows discussions from a variety of sources to spot edge cases in map data that could lead to undesirable routing or navigation. In this case, after following a discussion on a message board, an employee of the local road authority that covers the Koli National Park area in Finland tipped him off to the fact that routing engines from major mapmakers and navigation companies were sending drivers down the alarming route.

from Hacker News https://ift.tt/3AGc4O5