GIS Files 4: Putting it all in a system

4.4: Show me the way to go (2)

In-car navigation

By applying the principles of network analysis to accurate road data, you can build systems for motorists to navigate. Many cars now have gadgets that provide driving instructions, either as a simple map display or by audio messages. These in-car-navigation tools are actually specialised, miniature GIS. Because the data has attributes for road names and numbers, intelligent instructions can be provided (for example, 'take left turn A34 at next junction').

In-car navigation requires up-to-date map data and extra information to make the data model behave like the real world: you need to know which roads are one-way streets or where there are no-right-turn signs. By using unique identifiers in the road data so that each link in the network can be pinpointed, additional information can be built into the system. Furthermore, it is possible to receive real-time information about traffic conditions as you drive, so that you get advance warning if there are hold-ups due to road works or an accident.

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