Distance Decay

How far are you willing to travel to your destinations?

Distance decay is the concept of the friction of distance that causes issues while traveling origins to destinations. It is a geographical term affected by distance — could be measured in time, cost of travel, etc.

The shorter the distance the more likely travel will occur but the greater the distance the less likely travel occurs.

Source: An estimated distance decay function. Woo (2016)

Distance decay can refer differently to various things according to urban contexts. As an example, the density of traffic, street quality, quality of stores, height of buildings, price of land, etc. the decay weights (beta value) define the degree of migration to move less or further.

Source: Probability of walking to bus stops at different distances in North American cities. Reproduced from Transportation Research Board (2014)

Gravity metrics that differ by city environments or demographics — TRB measured people’s percentage of people walking to transit in different cities and as you can see the decay rate differs by type of city and by income.

The top dot-line is Calgary and the solid black line is small communities in British Columbia. People are more willing to walk longer distances in Calgary than in other cities.

Link: Reach, Gravity, Huff Model