Background

As global carbon emissions continue to rise, the need to reduce the number of privately-owned vehicles (POVs) on the road has become increasingly important.  In 2017, seven out of eight employees in the U.S. travelled to work by POVs. We created hypothetical scenarios of different modes of transportation and launched a survey to better understand how people’s commuting preferences can be altered.

Problem

Despite the positive impacts of alternative travel options such as walking or bicycling on both physical and mental health as well as the environment, many people still choose to drive to work alone (in single-occupancy vehicles, SOVs). Our research explores methods for altering people’s commuting behaviors through framing messages. We investigate whether the order of transportation options listed can influence people’s chosen preference of commute mode. We seek to determine if this strategy can be used to encourage the use of sustainable transportation modes and if bringing attention to factors of cost, health, and the environment can increase the likelihood commuters select sustainable modes as their preferred choice.

Research

To test the effect of framing on commuters’ stated preference, we partnered with researchers at the London School of Economics to survey 763 participants and provide participants with six commute modes to choose from: drive alone, carpool, train/metro, bus, cycle, and walk. All options listed the number of minutes it would take to use that mode for the participant’s daily commute. We tested whether the inclusion of additional information impacted commuters’ preferred transportation option. Participants were asked which mode they preferred after viewing the list of options and were given different lists depending on which condition they received. Participants were randomized into five conditions:

• • Control group- received a standard list of daily commute options that listed “Driving Alone” first
  • Favorable ordering- received a standard list of daily commute options that listed sustainable modes before the “Driving Alone” option
  • Calories burned + favorable ordering- received the favorable ordering list of daily commute options and provided an estimate number of calories that would be burned during the one-way commute for each option

• C02e emissions + favorable ordering- received the favorable ordering list of daily commute options and provided an estimate number of the pounds of emissions released during the one-way commute for each option
• Financial cost + favorable ordering- received the favorable ordering list of daily commute options and provided an estimate number of the financial cost of a one-way commute for each option

Figures 1-5. The list of commute options provided for each of the conditions.

Control:

Favorable Ordering:

Calories burned + favorable ordering:

C02e emissions + favorable ordering:

Financial cost + favorable ordering:

Results

We found that all treatment conditions significantly increased the likelihood that respondents selected a sustainable transportation mode over driving alone compared to the control group. The C02e emissions + favorable ordering condition significantly increased the likelihood of commuters stating a preference for alternative modes of transportation over driving alone when compared to commuters who only received the simple favorable ordering condition. Our results indicate that presenting the desired options first can increase the likelihood of people selecting those options. Additionally, including information on the environmental impacts of transportation modes along with a favourably ordered list of options can further increase the likelihood of people selecting sustainable transportation options.

Figure 6. Percent of participants selecting a desirable and sustainable commute option by condition.

Why It Matters

It is important to understand the ways in which people’s commuting preferences can be influenced. The findings from this study can be applied to efforts to encourage people to choose more sustainable transportation options to reduce the negative environmental impacts imposed by commuters who drive alone.  These findings were used to craft messages to solicit participation in a new University parking pricing program.