Personal mobility survey: the growing need for mobility is more important than the modal share of the car


The very heavy national survey on the evolution of French mobility behaviour that our country is only able to afford every 10 years has just been published. The clarifications it provides are based on figures and scientific arguments. However, between the climate emergency and the yellow waistcoats, they do not exhaust the debate, which ultimately remains fundamentally political.

Mathieu Chassignet, mobility and air quality engineer at Ademe, has a very relevant blog on mobility issues hosted by Alternatives Economiques. He brought to our attention the fact that the Ministry of Ecological Transition had just published the complete results of the 2019 "Mobility Survey of People". 
This is the very cumbersome and expensive national survey carried out about every 10 years and which measures the mobility of the French and compares it over time. The last edition was published in 2008 and, even though other sources are available to understand how these behaviours are evolving, the world of specialists in these questions was eagerly awaiting this publication and had had to make do with very partial elements until now. 

Like the 2008 survey, and using the same methodology that allows the figures to be compared, the survey called 'mobility of persons' and no longer 'transport and travel' sheds light on four main points  
- the vehicle fleet available to households (and the use made of it) ;
- subscriptions for public transport, motorways, car-sharing and self-service bicycles 
- the everyday 'local' mobility of the French;
- their long-distance mobility (which takes them more than 80 km from their home).

On his blog, Mr Chassignet offers his own summary of the results, looking successively at household equipment, their local mobility and their "journeys". He has made a post about it on LinkedIn and a debate with another expert, J. Coldefy, has emerged. 

The first fact that Mr Chassignet noted was that, between the two surveys, the number of vehicles per household increased for all categories of French people except the richest 10%, who were already very well equipped (more than 1.5 cars per household). Inequalities remain very high in this respect, since the households in the first decile have 0.69 cars and those in the ninth have 1.55. This inequality is doubled by the inequality associated with the place of residence: when households reside in communes 'outside the city' (rural areas), they have 1.55 cars, in Paris 0.91 and in 'areas of 700,000 inhabitants or more outside Paris' 1.21; in the areas of attraction of the cities, the households in the 'central communes' have 0.91 cars and those in the communes of the suburbs have 1.53. 
Thus, even if the 'modal share' of the car falls by a few points (from 64.8% in 2008 to 62.8% in 2019), the number of cars is continuing to increase and the number of kilometres/vehicle is rising with it. 

Obviously, since it is the fleet of vehicles that emits and generates congestion, this means that, over the past 10 years, the externalities linked to the car have not been reduced but increased, since the slight progress that has been achieved in terms of modal shares at the cost of great efforts has only made it possible to limit them to the margin. 
In these terms, this also means that the richer you are, the more polluting you are, firstly because you have more cars and secondly because the distances travelled per trip increase with income: the poorest 10% travel 5.4 km per trip and the richest 10 km. 
As the modal share of the car also increases with income, modest households are ecologically more virtuous than the richest. 
In fact, although there is an over-representation of the richest and the highest income groups in city centres, there is also more often an over-representation of the lowest income groups because there is a larger number of low-cost housing units and it is the most fragile part of the working classes that remain in the city after 30 years. 
In the same way, moving away from the central cities to have a little space is a choice made by households with children from both the advantaged and middle classes. Peri-urbanisation is basically a fairly general behaviour: using an agricultural metaphor, we say that city centres are breeding grounds, but not breeding grounds in the sense that people live there until their children are born, only to leave when they are there.

Jean Coldefy points out that: "Most of the kilometres are travelled by the middle classes, and this is what needs to be addressed. He provides breakdowns of journeys in terms of "passenger km": rather than reasoning in terms of the number of journeys, multiplying the number of people who travel by the number of kilometres travelled ("passenger km") makes it possible to identify the impact on emissions. Using these terms, Coldefy shows that the three deciles 5, 6 and 7 (corresponding to the median deciles) account for 37% of passenger km. He also shows that "peri-urban<->peri-urban" or "1st ring and central municipalities <-> peri-urban" trips account for 40% of the same total amount of "passenger km".

The comparison between the first decile and the 10th is misleading: the "problem" of the car and of public mobility policies essentially concerns the choice of peri-urbanisation, which is largely dominant and concerns a very large majority of households with children. The poorest cannot afford to move to the suburbs and the richest can avoid this residential choice. For the lower and upper middle classes, going to raise their children where they can breathe is an ultra-dominant choice. It corresponds in fact to peri-urbanisation which is only possible with very high and growing rates of motorisation and multiple motorisation.

From this point of view, moreover, Chassignet and Coldefy agree because it is a statistical fact. 

The former speaks of a deceptive improvement and writes: "The modal shares for local journeys are improving but that is not the main thing. Weekday distances travelled for local mobility have increased by 12% between 2008 and 2019, while kilometres travelled by car have increased by 9% (faster than the population which has increased by 4.5%).
He adds: "For long-distance journeys, people are travelling both further (+34% of kilometres travelled between 2008 and 2019) and using more and more of the most carbon-intensive modes of transport: planes now account for 43% of the kilometres travelled for long-distance journeys, compared with 30% in 2008.

Coldefy points out that "75% of km are for journeys of more than 10 km and 89% for journeys of more than 5 km". 
He adds: 
"From a climate point of view and for people (budget and time) it is not the number of journeys that counts but the kilometres. Modal shares in terms of the number of trips are useful for the occupation of public space in cities, but they have the major drawback of putting a 300-metre trip to buy bread on the same level as a 30-kilometre trip to work. The modal shares in km are those that count for GHG emissions."

Thus, the detailed examination of the survey tends to put the importance of modal shares into perspective and to emphasise the importance of the growth in mobility needs. For households with children, who have two salaries to mobilise and provided they have one or two permanent jobs with career or purchasing power progression, the suburbs are likely to remain the preferred mode of transport in the long term and to increase multi-motorisation and the number of passenger-kilometres. 
For journeys as well, the model of the richest people, which allows them to make five journeys a year rather than two, will be preferable and designating the most constrained as the bearers of a more frugal model which would ultimately be preferable, cannot be the answer. As Coldefy points out, research in geography, planning and sociology over the last few years no longer supports the idea that peri-urban areas (with the exception of the 'chic suburbs' or models such as the 'Vallée de Chevreuse') are areas of relegation where yellow waistcoats and FN voters thrive. 

Therefore, to consider that for climatic reasons and to avoid the continuation of the movement of land artificialisation, it would be necessary to break the movement and promote the model of the "compact city" is as technically defensible as it is politically untenable. 
The automobile issue today is first and foremost in these terms. 
The EPZs, for example, will have to be managed with these analyses in mind: in order to be able to bring up their children in conditions that the middle classes consider preferable, they have made residential choices that are linked to a strong dependence on the car. The possibility of equipping themselves with older and older vehicles kept for longer has made their situation manageable by continuously lowering the cost of the car. 
Reversing this de facto situation for climatic reasons may prove very difficult if desirable alternatives cannot be devised. 

For the moment, everyday mobility, like other forms of mobility, is what is known in economics as a 'superior good': when incomes increase - historically or between categories of households - the corresponding consumption increases more than proportionally... 

We may wish it were otherwise but not get it: we then dream that households love the planet so much and stop occupying space as they do. We can accept that this is the case, let households "spread out" and try to manage the effects as best we can.


The weekly column by Bernard Jullien is also on



GIS Gerpisa /
4 Avenue des Sciences, 91190 Gif-sur-Yvette

Copyright© Gerpisa
Concéption Tommaso Pardi
Administration Juan Sebastian Carbonell, Lorenza MonacoGéry Deffontaines

Powered by Drupal, an open source content management system