Understanding the variability of daily travel-time expenditures using GPS trajectory data

TL;DR

This study analyzes GPS data from 24 Italian cities to reveal significant variability in daily travel-time budgets, challenging the assumption of a universal constant and highlighting the influence of accessibility, stress, and individual behavior.

Contribution

Introduces a trip duration model with two parameters to describe travel-time expenditure distributions, accounting for variability across cities and individuals.

Findings

Travel-time budgets vary significantly across cities and individuals.

A stochastic model based on the Weber-Fechner law explains travel-time variability.

Factors like home location and trip frequency influence travel-time expenditure patterns.

Abstract

Transportation planning is strongly influenced by the assumption that every individual has for his daily mobility a constant daily budget of ~1 hour. However, recent experimental results are proving this assumption as wrong. Here, we study the differences in daily travel-time expenditures among 24 Italian cities, extracted from a large set of GPS data on vehicles mobility. To understand these variations at the level of individual behaviour, we introduce a trip duration model that allows for a description of the distribution of travel-time expenditures in a given city using two parameters. The first parameter reflects the accessibility of desired destinations, whereas the second one can be associated to a travel-time budget and represents physiological limits due to stress and fatigue. Within the same city, we observe variations in the distributions according to home position, number of mobility days and a driver's average number of daily trips. These results can be interpreted by a stochastic time-consumption model, where the generalised cost of travel times is given by a logarithmic-like function, in agreement with the Weber-Fechner law. Our experimental results show a significant variability in the travel-time budgets in different cities and for different categories of drivers within the same city. This explicitly clashes with the idea of the existence of a constant travel-time budget and opens new perspectives for the modeling and governance of urban mobility.