Why your map drifts in a tunnel

Why your map drifts in a tunnel

In a tunnel your phone can't hear the satellites, so it guesses.

It takes its last known spot, your speed and your direction, and works out where you should be now. Then it does it again from that guess. Every small error stays in, so in the 24.5 km Lærdal Tunnel in Norway, being just 1° off puts the dot 428 m from the road by the exit.

Send this to the friend whose map always panics in tunnels.

#gps #maps #howitworks #tech #tunnels