InterMob: a 24-month randomised controlled trial comparing the effectiveness of an intervention including behavioural change techniques and free transport versus an intervention including air pollution awareness-raising on car use reduction among regular car users living in Grenoble, France

Abstract

Background: Frequent car use contributes to health and environmental issues such as air pollution, climate change and obesity. Active and sustainable mobility (bike, walk, public transport, car sharing) may address these issues. Different strategies have been implemented in past research, involving hard levers, aimed at modifying the economical or geographical context (e.g., free public transport), and soft levers, aimed at modifying psychological processes (e.g., personalised transport advice). However, few studies have combined both hard and soft levers. In addition, few have used robust methodologies (e.g., randomised controlled trials), followed behavioural changes in the long-term, and been anchored in behaviour change theories. InterMob aims to address these limits by implementing a 24-month randomised controlled trial including hard and soft levers. The objectives of InterMob are to a) evaluate the effectiveness of an experimental arm versus an active controlled arm, and b) identify the processes of mobility change.

Methods: Regular car users living in Grenoble (N = 300) will be recruited and randomised to one of the two arms. The experimental arm consists in a six-month intervention combining hard levers (free access to transport/bikes), and soft levers (e.g., personalised transport advice). The control arm consists in a six-month intervention aimed at raising awareness on air pollution and its health effects. Both arms will include eight evaluation weeks (spread out over 24 months) based on a GPS, an accelerometer, and a pollution sensor. Moreover, participants will complete mobility logbooks and surveys measuring psychological constructs, socio-economical, and socio-spatial characteristics.

Discussion: InterMob will assess the effectiveness of two interventions aimed at reducing car use within regular car users in the short-, mid- and long-term. Moreover, InterMob will allow to better understand the psychological processes of behaviour change, and the socio-economical and geographical conditions under which the intervention is efficient in reducing car use. Finally, the benefits of mobility change in terms of physical activity, quality of life, and exposure to pollution will be quantified.

Trial registration: ClinicalTrials.gov : NCT05096000 on 27/10/2021 (retrospectively registered).

Keywords: Active mobility; Air pollution; Behaviour change; Car use; Daily mobility; Health; Psychology; RCT; Spatial organisation; Sustainable mobility.

Fig. 1

Followed steps for the elaboration, implementation and evaluation of InterMob. Source: Figure created by authors

Fig. 2

Procedure of the InterMob study since the ethics and data protection procedures to the study enrolment and beginning of the study. Source: Figure created by authors

Fig. 3

Map of InteMob study area. Map generated by authors from IGN BD TOPO and BD ALTI®

Fig. 4

Calendar of the intervention and the measurements. S = Session (seven-day measurement), M = Month, ap = appointment being part of the intervention. The icon of the green notebook represents seven days of carrying a Sensedoc and a MicroPem (the air pollution sensor is only carried during the sessions 0, 3 and 6), the icon of the GPS represents seven days of filling up a mobility logbook, answering a long survey (one time) and a short daily survey. Source: Figure created by authors

Fig. 5

Data collection sensors. In the left side, Sensedoc™ sensor (Accelerometer and GPS) which should be worn in a belt around the waist. In the middle, MicroPem™ (pollution sensor) which should be worn in a bag or purse with the pipe as close to the airway as possible. In the right side, the MicroPem™ and the Sensedoc™. Source: Figure created by authors