Promoting carpooling in China with motivational messages in-app and defaults

Carpooling presents a sustainable alternative to single-occupancy vehicles in China, given its rapidly growing urban population and reliance on private cars. We tested pop-up messages in a mock transportation app using a 4 x 2 between-subjects design (N=1600) testing the effects of three motivational messages – environmental benefits, carpool safety, and monetary savings (vs. no message control group). Furthermore, we tested the effect of placing the carpool option as the (default) first option shown to participants (vs. the second option), both in the choice for an urgent trip, and a non-urgent trip. Results showed that carpool was preferred for non-urgent trips, and placing carpool as the default choice in non-urgent trips increased average demand by 10% (4% in the absence of any message). For urgent trips, single-occupancy rides were preferred but presenting an environmental benefits or safety messages about carpooling significantly increased the odds of carpool being selected.