Car navigation: Wrong expected arrival times!

Car navigation systems can sometimes provide VERY erronous information. I did recently need to go by car in another part of the city of Brussels, Belgium. In the absence of public transportation, due to the terrorist attacks that occur just a few days before, I had to take the car for just around 6 kilometers. It was 17:20 and the arrival time was expected to be at 17:35. I was however caught in heavy traffic jams (oh surprise!). I finally did arrive at … 17:52. In normal times, traffic jams are very common and as public transportation were down, the streets were even more loaded than in normal times.

Car navigation systems
Car navigation systems

What is the accuracy of the arrival time of car navigation systems? It took me more than twice the time than calculated to get to destination. The error margin is by far not acceptable. By starting the system, the voice tells me however each time it would take into consideration the current traffic situation. Are you kidding me?! In the case of my example, I would have been less disappointed if the system told me from the beginning I would arrive at 17:52!

From my experience, the car I am driving in takes indeed the current situation into account in calculating the itinirary. BUT it only adds the additional time to the final counter! I never noticed my car navigation system suggesting me another route that avoids traffic jams on the way (bad system in my case?).

How does the system integrates the current traffic situation? Why is it so inaccurate in case of cities and/or traffic jams? Here are some of my thoughts about current systems:

  • The main lack of current GPS is that they simply do not take into consideration traffic lights. If going from A to B goes through point C, which is a crossroad, the system does not care at all about. It will simply add the time to go from A to C, and then the time to go from C to B. Let us add at least 1 minutes for every traffic light on the way (or the time the traffic light stays red)
  • The same thought can be done with crossroads without traffic light.
  • Car navigation systems do not take into account braking and accelerating at some points: crossroads, speed bumps, etc. In case of cities, they do a lot modify the arrival time!
  • Traffic condition information are not processed in an optimal way. My guess is that the position of cars are centralized “somewhere” and traffic jams are calculated where there is a car crowded area. Why not overestimating the additional time?

What are your experiences with car navigation systems? Are they working better at your side than mine?

Click here to see how Subaru sees the embedded GPS UI.

Thanks a lot for sharing the information!



2 thoughts on “Car navigation: Wrong expected arrival times!

  1. Hi Daniel,

    My car gave me always good arrival time estimation, but it’s true that I’m not driving in Brussels where there is maybe more a mobility global issue than specific GPS issue. I don’t know on what your system is based, but could be interesting to test different one?



    1. In Brussels, the traffic is like hell, even for small distances. I use my phone embedded GPS but it’s true that using Waze is much more accurate.
      Veeery difficult to be accurate when it comes to arrival times in a city, in general.

      Thanks for the comment 🙂


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