The area of route planning research got a large boost with the 9th DIMACS Implementation challenge in 2005/06, this is where most of the research into fast and

The area of route planning research got a large boost with the 9th DIMACS Implementation challenge in 2005/06, this is where most of the research into fast and exact route planning algorithms started. (What sat nav vendors did and are still doing usually isn't exact, they were using inexact heuristics that were based on the 'natural' hierarchy in the road network)