Digital Nudges for Greener Transport Choices in the US

What unsustainable behaviour needs to change:

Transport behaviours are notoriously difficult to shift, largely because they are ingrained habits. During the COVID-19 pandemic, reduced commuting and increased remote work led to significantly decreased traffic levels in the US. However, by early 2022, traffic volumes were back above pre-2019 levels. This rebound highlights a key sustainability issue: private car use remains the default commuting option for many Americans, contributing to transport being responsible for 28% of US greenhouse gas emissions.

Addressing this challenge, a collaboration between The Behaviouralist, travel app Metropia, and the San Francisco Bay Area’s Metropolitan Transportation Commission (MTC) aimed to understand and influence commuter choices. A survey identified perceived barriers: cars were seen as convenient and without obstacles, while alternatives like carpooling and public transport were viewed as unreliable or unsafe. This insight led the team to test whether digital nudges could help shift these entrenched preferences.

The Green Nudge:

The Metropia GoEzy travel app provided a platform for testing two types of nudges with 216 participants recruited through social media.

• Experiment 1: Information Nudges – Participants received in-app messages about the societal costs of driving and reminders linked to green identity, while a control group received no messages. This experiment focused on non-habitual trips.
• Experiment 2: Incentive Nudges – Participants were offered small monetary incentives, redeemable for gift cards, if they reduced car use or opted for sustainable transport modes. This experiment aimed at influencing habitual commuting behaviour.
  

The result: The outcomes were insightful. In Experiment 1, messages highlighting the high societal cost of driving prompted slight behaviour changes, but green identity reminders showed no measurable effect. In Experiment 2, modest financial rewards ($3-$5) successfully nudged users toward intermodal travel but did not significantly reduce car use. Notably, individuals identified as “flexible travellers”—those already using multiple modes of transport—responded best to these nudges. This suggests that focusing on this adaptable group could yield greater success in future sustainable transport interventions.

Are you aware of any other nudges that help to promote green mobility? Feel free to comment or get in touch: hello@green-nudges.com