The mean passenger transport speeds across time in France, its determinants, and the interaction with transport demand

Abstract

Transport demand appears as the main determinant of past transport emissions in France, so it is important to better understand its drivers. In relation to relatively constant travel time budgets of around one hour per person per day (known as the Zahavi conjecture), the mean speed of passenger transports largely influence the number of kilometers travelled. The aim of the study is to quantify the evolution of the average travel speed from 1960 to 2017. The analysis shows the importance of modal shift from walking to cars as the dominant cause of acceleration, followed by the increasing speed of cars allowed by the growing share of traffic taking place on highways. At the beginning of the 2000s, a peak in the mean speed is observed, mainly explained by the slowdown on the roads due to road safety policies. It was probably one of the causes of the peak travel observed at that time, with the travellers choosing to reduce their mobility in order to preserve their travel time budgets. It seems that the recent trend of stagnation could be persistent in the next decades, potentially confirming the turn of the millennium on transport speeds and kilometers travelled per person in France.