Distance Decay: How Far Are You Willing to Travel?

distance decay
Distance decay is the concept that people are less likely to travel larger distances to interact with another locale. How do you apply distance decay in your every day life?

Last Updated: Oct 15, 2017

How do store planners use distance decay?

Distance decay is the idea that the farther away you are from goods or services, the less likely you are to make use of it. For example, if you live in a rural area, it’s likely that you travel to a bigger city 100 miles even if it offers bigger and better goods and services.

So a store’s distance has an impact on how many customers it can attract from nearby towns. This varies from place to place with less connections or transportation hindering impact of distance.

Geographers think that you can apply the idea of distance decay all over the world.

And it doesn’t only apply to city planners. For example, industries like agriculture use distance decay to shorten travel time to nearby supplies like water and fertilizer for fields.

Friction of distance vs time-space compression

If you want to build a store, planners should always consider distance decay as the main driver for customers. Because they know customers are only willing to travel a certain distance to shop there, they can select their store site based on the population nearby. This concept is friction of distance and is the cause or barriers that hinder interactions.

Because they know that potential customers are only willing to travel a certain amount of distance, major corporations have teams of planners use distance decay before they establish a store location. They think of friction of distance questions like:

  • Are customers willing to travel one hour to the nearest shop, if it’s a bit bigger?
  • Or are customers more likely to travel 15 minutes to a smaller shop?

For example, they use tools like Huff’s Gravity Model for planning scenarios to ultimately pick the best building site.

Huff Gravity Model
The Huff Model illustrates the probabilities of consumers at each origin location patronizing each store.

We can think of time-space compression as factors which reduce the impact of distance decay. For example, wealth, technology and transportation system can reduce the impact of distance-decay.

  • Are there any subway systems or bus routes that make it easier for people to access this site?
  • Can people afford to own a car and travel this amount of distance to patron the store?

For example, subways, trains and faster cars all lessen the impact of distance decay. But more than a century ago, when people’s main transportation were horse and buggy, time-space compression wasn’t as big of a factor as it is today.

Geographers build isochrone maps to find how far firefighters, ambulance or paramedics can service a city or town. In addition, they pick optimal business space with location-allocation to maximize coverage of their services.

What are distance decay examples?

As the distance between two locales increases, the amount of activity between them decreases. Likewise, if you build a store in the middle of nowhere unconnected to transportation, no one will visit your store.

The idea of distance decay has been applied since the beginning of human civilization. Farmers who water their field, they are going to keep their supply of water as the shortest route as possible. They don’t want the distance to be very far.

Think of going to a park or shopping and your experience of distance decay? How does Waldo Tobler First Law of Geography describe relationships between close and far things?

Take the time to write down some of the stores you patron, and if you are applying distance decay in your everyday life. Find some new stores on the map, and picture how likely you are to travel to go there.

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