car expertA navigation system can predict the arrival time, but reader Alwin Kalt wonders how it is possible that the time keeps changing along the way. Our car expert Niek Schenk answers.
Ask: ‘Why is it that my navigation system indicates that I still have 63 minutes to drive to my destination, but that time occasionally jumps to, for example, 64 or 65 minutes? While during that time, for example, I drive 130 where I am only allowed 100? Wouldn’t you say that the predicted travel time should be reduced rather than added?’
Auto editor Niek Schenk replies: ‘A modern navigation system is dynamic. It is mainly based on the maximum speeds that may be driven on the routes in question. If you drive faster than the local speed limit, the system will not immediately anticipate this. But ultimately yes, because the higher driving speed means you will arrive at the next GPS position sooner.
In addition, more and more systems are taking current traffic information into account. The busier your route is, the later the expected arrival time will be. For example, it may happen that the arrival time changes regularly during your trip, because it becomes busier or quieter on the route.
There is also a difference in the type of traffic information that the system can receive. The somewhat older systems, in particular, are based on traffic information as regularly distributed by radio broadcasters. More accurate are the systems that rely on online information, such as from Google Maps or TomTom. Such a system works in real time and is therefore much more up-to-date.’
Our car editor Niek Schenk answers reader questions every week. Mail your question to [email protected]
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