Why Drivetimes Don't Define Catchments

Historically, retail catchments have been defined using:

• circles (1980’s)
• drivetimes (1990’s)
• gravity models (21st century)

Drawing a circle to define a retail catchment was superseded by the advent of drivetime databases, which measured the time spent by consumers travelling to a retail facility. Although still popular, even the Competition Commission acknowledges that drivetimes don’t define catchments because they don’t take account of retail competition. Gravity models do though, and the RSPM is the most advanced gravity model available in the UK.

The RSPM takes proper account of the two key consumer motivators:

• Accessibility to retail facilities (measured by drivetime)
• The relative attractiveness of retail facilities (measured by the scale and variety of brands)

It also takes account of changes to housing, population, roads and spend patterns.

Changes to Housing and Population

Using the example of Dublin, where more than 40 sites are zoned for housing development between 2000 and 2006, no gravity model could accurately forecast spend without incorporating such changes.

Changes to Housing Around Dublin 2000 - 2006




Changes to Roads

The examples below, also showing Dublin, reveal how new motorway links around Cherrywood (South of Dublin) dramatically change Cherrywood’s drivetime accessibility.


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© Copyright ORC and AND International Publishers. All rights reserved.


Drivetimes vs Gravity Models

Using drivetimes alone as a guide would imply that, after road changes, Cherrywood’s catchment for a particular retailer would expand substantially to the North West.

The following two maps show how intense competition (shown as dots) to the North West severely restricts catchment expansion in that direction.


RSPM Catchment of Cherrywood Before Road Changes


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RSPM Catchment of Cherrywood After Road Changes


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Conclusions

Using drivetimes only can dramatically understate or overstate the geographic size of the catchment and give an unreliable forecast of market values.

As a gravity model, the RSPM provides the opportunity to significantly improve spend and sales forecasting.