The 30 axis: a necessary complement to the 30 zone?

At a time when Paris is considering making the 30 km/h speed limit ubiquitous, except on structural axes, should these major axes not be integrated within a policy of reducing speeds in town?


As part of research funded by theRoad Safety Foundation in partnership with IFSTTAR and the City of Paris, 6t research conducted a study aiming to understand the effects of a 30 km/hr speed limit on structural axes. No assessment has yet been made on the structural axes changing from a 50 km/h speed restriction to a 30 km/h restriction, or on the acceptance of users faced with such a measure. Given its empirical nature (qualitative interviews conducted with 40 people, as well as a survey of a sample of over 2000 users), our research provides a before and after assessment of this problem relying in particular on the recent speed limit change to 30km/h Avenue Clichy (Paris, 17th and 18th arrondissements).

Academic literature had already amply demonstrated that the impact of a 30 km/h speed limit is demonstrable, where improving road safety is concerned, but is more questionable as regards noise and pollution. This fact was confirmed by our field visit: the respondents (whether travelling on foot, by car, by motorised two-wheelers or on public transport) consider that the lowering of the speed limit to 30 km/h on the Avenue de Clichy is primarily a response to road safety. A lack of road safety characterised by pedestrian crossings which are impossible or dangerous. Moreover, after the speed limit was changed to 30 km / h in the Avenue de Clichy, 77% of respondents found the crossing easier.

Thus, besides road safety issues, limiting the speed limit to 30 km/hr on main roads could restore the so-called transversal functions of these axes (their activities, housing, meeting places, travel on foot and by bicycle, etc.) which have too long been neglected in favor of a single, longitudinal function: road travel.

But what is the acceptability of such a measure, and what would the conditions of its implementation be, from user to user?

The survey shows that the acceptance of a speed limit change to 30 km/hour on main roads is high: 85% of users are in favour of such a measure. Even users of individual and motorized modes of transport (cars and motorcycles) are 59% in favour. While users sense that there is improved safety and ease of pedestrian crossings, they still fear a potential increase in existing traffic. This therefore raises the challenge of communicating the fact that in cases of congestion, one is already traveling at less than 30 km/hour!

82% of users state that they will observe the speed limit, even motorists (75%) and users of motorized two-wheelers (69%). To enforce the speed limit of 30 km/h, users consider that beyond the remodelling, a combination of preventive and repressive measures should be offered. 61% of respondents noticed changes thanks to the adjustments, but only 1/3 of respondents noted the decrease in the regulatory speed limit. The remodellings “signal” the improvement of the public space, but they alone are not able to create acceptance. 56% of respondents believe that information pedagogy is essential in order for the speed limit to be observed. Depending on the users and their expectations, this pedagogical dimension may take three major forms:

  • pedagogical radars;
  • clarification on the links between congestion and speeds practiced;
  • clarification of the relationship between pollution and speed.

Therefore, if road safety issues in cities present an opportunity to reflect upon a dimension of speed, is the change in the speed limit from 50 to 30 km/hr not the right opportunity to offer a new relationship with the city, whatever the type of pathway?


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Photo credit: 6t research, 2014

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