Evaluating the Effectiveness of Sustainable Transport Alternatives in Reducing Car Use: A Large-Scale Field Test

Provision of alternative means of transport free of charge for 6 months.

From May 2023 to October 2023, all participants in the treatment group receive either an e-bike free of charge, provided by a bike rental company and delivered to their doorstep, or a free “DeutschlandTicket” via postal mail, which is a ticket that allows access to public transport throughout Germany (only excluding long-distance trains, such as intercity trains). We assign the specific means of transport (e-bike or public transport ticket) based on the participants’ previous survey responses. Specifically, we first assign an e-bike to those participants who already own a ticket for public transport, and vice versa. For the remaining participants, we look at their baseline willingness to pay for an e-bike and a public transport ticket and assign the participants the means of transport for which they indicated a higher willingness to pay. In addition to the e-bike or the public transport ticket, participants in the treatment group receive some practical information that can further increase the usefulness of the provided means of transport (e.g., information about apps that provide real-time information on train schedules or that help plan bike routes).

See attached PAP for more information.

2023-05-01

2023-10-31

Measures of the participants’ car use, their use of the provided alternative means of transport, and their willingness to pay for the alternatives means of transport.

(I) The average distance (in km) traveled by car based on monthly elicited odometer readings of the participants’ used cars,
(II) the average use of the provided alternative means of transport as measured by self-reported trips made and kilometers traveled in the previous week (elicited in the monthly surveys),
(III) the willingness to pay for the alternative means of transport (elicited at various points in the study, including the baseline phase and also in the control group, as the willingness to pay to be provided with the alternative means of transport for a specified period of time after the completion of the study).

See attached PAP for more information.

Alternative operationalizations of the primary outcomes to account for possible spillover effects of the intervention within the participants’ households, purposes of mode use (commuting or other trips), and well-being during travel.

In our secondary analyses, we look at alternative operationalizations of primary outcome (I), namely on (I.a) odometer readings of the participants’ used cars accounting for the self-reported share of kilometers traveled by other household members, (I.b) odometer readings of participants whose self-reported share of kilometers is 100% over the whole study period, (I.c) odometer readings of participants living in single households, and (I.d) self-reported car use in the previous week (elicited in the monthly surveys). Furthermore, we investigate the effect of our treatment on (IV) purposes of mode use (commuting or other trips) as well as on (V) well-being during travel, e.g., whether traveling is perceived as comfortable or stressful.

See attached PAP for more information.

Randomized controlled trial with a baseline period, an intervention period, and a post-intervention period.

We conduct the field study for a period of 15 months, starting in November 2022 and ending in January 2024: there is a baseline period of 6 months, an intervention period of 6 months, and a post-intervention period of 3 months.

To collect data on the kilometers driven by car by the participants and further information on their mobility behavior, we use short monthly surveys during the whole study period as well as a longer baseline survey right in the beginning, yielding 15 surveys altogether. In each of these surveys, we ask participants to report the current odometer reading of their car. Moreover, we ask participants to upload photos of their odometer several times during the study period to validate the reported odometer readings. In case there is more than one car in the household, we ask them to report the odometer readings of all their used cars.

Additionally, we ask participants each month about their mobility behavior in the past seven days and whether there have been any larger changes to their life situation that may have affected their mobility behavior since the last survey or may affect their mobility behavior in the future.

Randomization into the control and treatment groups took place toward the end of the baseline period. We used a stratified randomization procedure taking the following variables into account: Baseline car use, baseline willingness-to-pay for an e-bike and a public transport ticket, e-bike and ticket ownership.

The experimental design consists of one control group and one treatment group. All members of the treatment group (regardless of whether they receive an e-bike or a public transport ticket) are combined as one group in the main analysis and evaluated together. Thus, the treatment can be understood as the demand-oriented provision of one of the - according to our survey data and expert assessments - two most attractive alternative means of transport.

See attached PAP for more information.

Randomization done in the office by a computer.

Individuals

No

674 individuals

674 individuals

Control group: 314 / Treatment group: 360

7-8% (see attached PAP for more information)