THE TRAVEL TIME BUDGET AND URBAN STRUCTURES
The travel time budget teaches us that cities can follow quite different courses in their evolution and yet maintain a stable travel pattern. Historically, this has resulted in distinctly different urban structures offering roughly the same level of access. How do these structures differ, and what unites them?
In an idealistic comparison, we could look at three different cities, each with a transport infrastructure centred around a specific means of travel.
- Walking: In a city with a dense core (0-2 km) dominated by walking trips, the potential level of access would be evenly distributed among the city’s ambulatory citizens.
- Driving: A city centred around driving would be more dispersed and have a much larger radius (0-40 km). Its potential level of access would be high for those with cars but low for other groups.
- Public transport: A public transport-oriented city would be dense and concentrated around station areas (0-20 km radius). The city’s potential level of access would decrease with the distance from stations.
Comparing these idealistic examples from the TTB perspective, the following can be stated:
If the travel time budget acts as a land use regulator, any increase in the average speed of the transport system leads to an (almost) equivalent decrease in population density and an increase in the dispersion of destinations. Thus, in terms of access, neither urban structure is more effective than the other.
Owing to the close relationship between travel and land use, a city exclusively based on walking can offer the same access in everyday life as a city based on automobile travel. While the walking-based city can offer equal access for anyone capable of moving around on foot, the automobile city offers an acceptable level of access merely for those guaranteed to travel with the high speeds offered by car.
A comparison of travel time use in cities in France, Belgium and Switzerland analysed factors that influence individuals’ travel time budget. The study found that access to cars and public transport infrastructure plays a minor role, while socio-economic and other factors (i.e., gender, age and presence of children in the household) had a greater influence on travel time budgets.
Put simply, the amount of time you spend on everyday travel is more a result of who you are than of the physical characteristics of your city or the modes of travel you use. Likewise, two cities can provide a different array of transport options and yet have the same distribution of travel time among their citizens.
Read full report: For additional details, discussion and recommendations, read the full report “RUNNING TO STAND STILL – THE ROLE OF TRAVEL TIME IN TRANSPORT PLANNING“.
This Urban Insight report describes a phenomenon that is essentially a universal law of travel, with implications for both urban and transport planning. Its validity spans historical eras, as well as diverse cultures and cities. It touches upon what constitutes a limit for human behaviour and seems to affect the size and density of urban areas.