Fig. 6: Travel time decay curve for commuting flows between SA2s.

This figure shows how the likelihood of commuting between areas declines with increasing travel time. Data on car-based commuting flows between Statistical Area Level 2 (SA2) regions were sourced from the Australian Bureau of Statistics and analysed using drive-time estimates between SA2 centroids. Commute durations were grouped into one-minute intervals up to 149 min. a shows the standardised probability distribution of trips in cities. b shows the inverse cumulative distribution of trips across the same groups. A negative exponential function was found to best represent the pattern of trip frequency decline, with a decay rate of 0.058. This function, commonly used in transport studies, reflects how people are less likely to commute as travel time increases.