GIS Files 4: Putting it all in a system

4.4: Show me the way to go (3)

Drive-time analysis

Another benefit of network analysis is the ability to calculate drive times, which identify how far you can travel in a certain amount of time.

The typical drive-time map - for example, for pizza delivery - would show a central point surrounded by a series of circles estimating how long it takes to get to places within that radius. This method assumes an as-the-crow-flies route to each location.

A GIS can be much more accurate - it can use network analysis to generate isochrones (lines that join up points of equal travel time) that take into account the true road network and give a proper measure of how far you can get over a set time. This can even take into account the average speed on each road, so that the area appears stretched along faster roads.

Many different organisations use this kind of drive-time analysis to plan their operations, from the siting of new stores to the planning of distribution networks.

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