What is it?
Travel Time Budget refers to the time people spend travelling per day. It can be defined as the average time people are willing to spend on transport within a day. The concept of travel time budget is closely linked to the hypothesis of constant travel times, also known as Marchetti’s constant.
The constant travellers

Research in human geography shows that travel times are remarkably constant. This observation goes back to Marchetti (1994) and has since been confirmed many times in different historical, geographical, and cultural contexts. On average, people spend around an hour per day travelling, irrespective of the mode of transport. The remarkable consistency of travel time over space and time periods suggests a kind of ‘natural’ travel time budget of around 70 minutes per person per day.

This constancy of travel time casts doubt on the common narrative that transport investments lead to time savings. Rather than reducing time spent on transport, such investments tend to result in individuals making longer trips while maintaining their travel time budget of approximately 70 minutes (+/- 10 minutes).


The same applies to leisure trips, which are also included in the travel time budget. Studies on travel behaviour during the Covid pandemic have shown that time savings made through digital meetings are commonly re-invested into added leisure trips, reinforcing the idea of constant travel time budgets.


A healthy amount of movement

Deviating from this ‘natural’ travel time budget is likely to have negative consequences. The relationship between longer commutes and physical and mental health issues is well-explored. Furthermore, the Covid pandemic showed that the lack of travelling can have negative consequences as well. The loss of daily structure (routine) and limited interactions due to the lack of travel have similar negative effects.

Despite the remarkable constancy of travel time budgets, variations exist among different groups of people. For instance, single parents typically have higher travel time budgets, while individuals with physical disabilities tend to spend less time travelling. City design can also influence travel times, potentially forcing people to exceed their ideal travel time budget.

  • Marchetti, C. 1994. “Anthropological Invariants in Travel Behavior.” Technological Forecasting and Social Change 47 (1): 75–88.


Further Reading
  • Ahmed, Asif, and Peter Stopher. 2014. “Seventy Minutes Plus or Minus 10 — A Review of Travel Time Budget Studies.” Transport Reviews 34 (5): 607–25.
  • Millonig, Alexandra. 2022. “Defining a Minimum Standard for Mobility,” MyFairShare Discussion Paper.
  • Mokhtarian, Patricia L., and Cynthia Chen. 2004. “TTB or Not TTB, That Is the Question: A Review and Analysis of the Empirical Literature on Travel Time (and Money) Budgets.” Transportation Research Part A: Policy and Practice 38 (9): 643–75.
  • Panchal, Nirmita, Rabah Kamal, Cynthia Cox, and Rachel Garfield. 2021. “The Implications of COVID-19 for Mental Health and Substance Use.”