InterMob: a Randomized Controlled Trial Aimed at Reducing Car Use in Regular Car Users

Aina Chalabaev

Status: Invitation-only

Conditions: Automobile Driving; Active Commuting

Treatments: Behavioral: InterMob: a randomized controlled trial aimed at reducing car use in regular car users; Other: Active control: Air pollution information

Study type: Interventional

Funder types: Other

Identifiers

NCT05096000

INTERMOBFRUGA

Details and patient eligibility

About

Regular car use is a source of pollution and physical inactivity. InterMob is an interdisciplinary randomized controlled behavioral intervention aiming at reducing car use. The objectives of InterMob are to a) Evaluate the efficacy of a theory- and evidence-based intervention, b) Identify the mechanisms related mobility change, and c) Identify the conditions under which the intervention is effective.

To meet these objectives, 300 regular car users living in Grenoble will be recruited and randomized in one of two arms:

1. experimental group that will receive the InterMob intervention: six months of free public transport/access to a bicycle, and behavior change techniques (personalized transport advice, setting of mobility change goals, considering possible obstacles; 6 months of motivational messages to prompt goal setting and self-monitoring).
2. active control group that will receive information about air pollution (discussion about the health consequences of air pollution, the association between air pollution and car use; 6 months of messages to prompt air pollution monitoring.) Follow-up measures will be carried out until 24 months after the beginning of the study (8-day measurement sessions). Five sessions will involve wearing a GPS/accelerometer, and an air pollution sensor. Participants will complete mobility logs and questionnaires measuring the psychological mechanisms related to their mobility (habits, intentions, self-efficacy), and socio-economical characteristics (number of children, accessibility) during the 8 sessions.

The investigators hypothesize that the participants allocated to experimental group will reduce the car use and increase the use of alternative modes to the car (biking, walking, public transport, and carpooling) more than the participants of the control group, and that these changes will remain. The investigators hypothesize that mobility changes will be mediated by intention and self-efficacy. The investigators hypothesize that the efficacy of the intervention will be moderated by socio-spatial factors (number of children, travel distances) and psychological factors (self-control).

The main criterion will be car use reduction and the use of alternative modes to the car. In addition, the investigators will assess physical activity (minutes of moderate-to-vigorous physical activity), the exposure to air pollution, the quality of life and the carbon footprint associated to transport.

Full description

Sample size : The investigators have calculated the sample size considering :

• the proportion of trips made by car (49% of the trips made in Grenoble Metropole are made by car according to the EMD, 2010 which is the most recent survey in the area currently available),
• the potential target population's transport behavior (a percentage of the population can be classified as reluctant drivers with positive attitudes toward other modes of transportation, this population makes 80% of their trips and could potentially reduce their car use to 64% considering the characteristics of the trips)
• the impact of past interventions (car reduction of -17%, from 50% to 33% of car use, Brockman & Fox, 2011).

The investigators considered a statistical power of 0.8, and a significance level of 0.05 for a proportion of 80% or 50% of trips made by car in the control group. In order to detect a difference of 15% when the share of trips made by car is reduced from 80% to 65% or from 50 to 35%, the investigators need 300 individuals (i.e., 150 individuals in each group).

Enrollment: 400 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Being at least 18 years old at the time of inclusion

  • Profile: employed / unemployed / retired / on work-study or apprenticeship

  • If employed : Work and live in the SMAAG territory (Metropole of Grenoble + Grésivaudan + Pays voironnais)
  • If in apprenticeship/training program: Working, studying and living in the SMAAG territory (Metropole of Grenoble + Grésivaudan + Pays voironnais)
  • If unemployed / retired : Reside in the SMAAG territory (Metropole of Grenoble + Grésivaudan + Pays voironnais)

• The car/motorcycle/scooter is the main mode of travel during the week (excluding weekends)

• Travels 3, 4, or 5 days by car (excluding weekdays)

• Thinks about reducing car use or has started to reduce car use - Expect to live and work in the Grenoble area in the next 2 years (Very likely and likely options)

Exclusion criteria

• Being a student
• Living outside the Metropole of Grenoble + Grésivaudan + Pays voironnais
• Working outside (Metropole of Grenoble + Grésivaudan + Pays voironnais)
• Studying outside (Metropole of Grenoble + Grésivaudan + Pays voironnais)
• Car/motorcycle/scooter is not the main mode of travel
• Travels 0, 1 or 2 days a week by car
• Does not intend to reduce the frequency of car use
• Does not expect to live and/or work in the Grenoble area in the next 2 years

Trial design

Primary purpose: Prevention

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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400 participants in 2 patient groups

InterMob: a behavioral and economical intervention

Experimental group

Description:

* 6 months of free transport/bicycle (12.5 Adding objects in the BCT, Michie et al., 2011) * Two meetings with a coach : 1. st meeting: discussion about the motivations to change (motivational interviewing and 5.2 Salience of consequences, BCT), personalized advice of transport (4.1 Instruction on how to perform the behavior, BCT), mobility change goals, and action planning (1.1 Goal setting and 1.4 Action planning, BCT), solutions to possible obstacles (1.2 Problem solving, BCT) 2. nd meeting: discussion about the goals and the obstacles lived and resolved. If needed, personalized transport advice is given. * "Goals notebook" to fill up for 6 months (goals need to be set every 2 weeks and obstacles if experienced) * Weekly SMS during 6 months, prompting a) to set and adapt goals (1.7 Review outcome, BCT) and b) to do a self-feedback related to mobility change (e.g. a more important well-being) (2.4 Self-monitoring of outcomes, BCT's taxonomy)

Treatment:

Behavioral: InterMob: a randomized controlled trial aimed at reducing car use in regular car users

Air pollution information: an informational group

Other group

Description:

Active control group focused on air pollution information: * Two meetings with a coach: 1. st meeting: Discussion about air pollution (definition, sources, population most affected, levels in Grenoble, the consequences on health, pollution peaks), air pollution and car use (video about the pollution exposure of car drivers and the consequences of fine particles) and, a discussion about the benefit and disadvantages of using a car (5.2 Salience of consequences according to BCT's taxonomy) 2. nd meeting: Discussion about air quality during the last weeks and they check the quality of air of the last week. * "Observation notebook" to fill up for 6 months (quality of air in Grenoble and the pollution peaks every 2 weeks) * Weekly SMS during 6 months prompting a) to write down the air quality of the air every two weeks and b) write down any pollution peak announced in the television/radio/telephone

Treatment:

Other: Active control: Air pollution information