A paradox of industrialized society is the overreliance on unsustainable fossil fuel energy for transportation and insufficient use of sustainable

bodily energy for more physically active modes of transport. Different modes of transportation require varying levels of physical activity, with cars

being the most sedentary, followed by public transportation, and active transportation (walking and biking). Preference (individual and societal)

for sedentary travel modes such as car driving over available physically active travel modes has contributed to air pollution and the epidemic of

obesity. Low-carbon transport systems have the potential to improve the health of citizens and to mitigate climate change simultaneously.

Among the potential solutions for low-carbon transport systems, innovations in technology and demand reduction have received much attention,

with less consideration toward behavioral options that are also critical to a decarbonized transport sector.

Currently, behavioral change options are rarely considered in the decision-making process of transportation projects because their efficacy is

largely unknown. An example of behavioral option for decarbonizing transport is a non-price-based policy to trigger individual behavioral change

using “nudges”, defined as any aspect of a choice set that alters behavior without foreclosing alternatives or significantly changing economic

incentives. The intervention should be easy and cheap to implement; for example, a nudge could disclose information. Evidence has emerged

that the American public has a knowledge perception bias for energy consumption and efficiency that tend to underestimates carbon emission of

day-to-day activities. This study investigates whether insufficient and inaccurate perceptions of carbon emission and bodily energy expenditure

in day-to-day travel may be barriers for adopting more physically active and environmentally sustainable travel modes.

We conducted a randomized controlled trial to assess impacts of a behavioral nudge intervention consisted of a new smartphone app onTrac.

The app was developed to report personalized knowledge of carbon emission and calories burned associated with user specified travel modes,

with walking and bicycling automatically detected through accelerometer. Undergraduate students of Queens College, City University of New

York were recruited to participate in baseline surveys (N=85) designed to evaluate factors that may influence their travel mode preferences and

behavior. Although both car and public transit commuters are found to be pro-environment, they are significantly different in that public transit

commuters displayed less affection towards driving and were more comfortable using public transit (attitude factors), were more encouraged by

their families to use public transit and had more friends who use public transit (norm factors). Transit commuters also had less situational

constraints such as owning an automobile for work and managing their schedule than car commuters. Repeat surveys following a three week

trial of the onTrac app found significant increases in self-reported consideration for the environmental impact of transportation choice among

students who used the app (N=24), compared to the control group (N=26) who did not. Significantly more favorable attitudes towards carpooling

post-trial were noted only among the car drivers (N=12) in the app group. Further studies, with larger sample sizes and an improved app that

can detect all travel modes automatically using the smartphone's built in sensors are warranted to explore how this elevated environmental

cognition may interact with attitude and situational factors, perhaps moderated by perceived control, to influence actual travel choice behavior