How satnav maps are made

When a lorry driver wedged his 13-tonne truck between a house and an estate agent in Somerset recently, the media was quick to point the finger of blame at a familiar culprit – the 6in screen sitting on his dashboard.

Flawed satnav instructions are the scapegoat for ridiculous round-trips, buses wedged under bridges, and ambulances taking life-threatening diversions. But few understand or appreciate how far mapping companies go to ensure the accuracy of the data they’re providing.

And, of course, we rarely hear of the millions of gallons of petrol saved or countless hours of business productivity recouped by the millions of satnav users who shave 10 or 20 minutes off their journey times every day.

In this feature, we’ll reveal the extraordinary efforts companies make to create and update their maps, and continually verify their accuracy, as well as sparing drivers from hours of sitting in traffic jams with the use of real-time data. We’ll also show just how much maps can differ from one provider to another.

What’s in a map?

The foundation of all modern voice-guided navigation is the underlying maps. Modern digital maps aren’t simply lines and icons displayed on a screen; they’re billions of vector points plotted in geographical space, supplemented by an enormous volume of metadata, specifying factors such as road width, speed limits, height and weight restrictions, house numbers, and even the camber and surface type of a road.

There’s postcode lookup data for locating destinations quickly, historic and live traffic information, lists of points of interest (POI), physical geographic features and building footprints.

With this much data to process, it’s a miracle any company is able to maintain an up-to-date map for one country, let alone many worldwide, yet there are four such organisations in existence, all doing things differently.

The two main sources of digital mapping in use by satnavs in the UK are Tele Atlas (owned by TomTom) and Nokia (previously Navteq). Then there’s Google and the open source, user-generated OpenStreetMap. The manner in which these companies create and maintain their maps varies enormously.


Based in Chicago, Navteq has been producing maps for navigation products since 1985, and was acquired by Finnish mobile phone giant Nokia in 2008.

The company has come a long way since it first installed its kiosk-based navigation products in car-rental offices in the San Francisco Bay area, and now maintains a mapping database covering all 190 UN-recognised countries.

Nokia’s mapping data is used in more than 100 countries in turn-by-turn, voice-guided navigation, and in the UK the company’s maps are employed by hundreds of different satnav products.

Navteq supplies mapping data to most of the world’s biggest car brands for their dash-mounted systems, you’ll find them in Garmin’s satnavs and, of course, Nokia’s free Drive product, which comes preinstalled on the firm’s Windows Phone smartphones. The popular CoPilot Android and iOS apps also use Nokia/Navteq-generated data.

Nokia Lumia satnav

Why is it so popular? CoPilot’s David Quin explains: “We have a QA team driving continuously – not only with our app, but also with other apps [based on rival data]. Navteq offers a [more] consistent experience, in particular about things such as speed limits, lane guidance and turn restrictions.”

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