This case study intends to understand spatial variation of students’ low-carbon transport (LCT) modes to a commuter university. The LCT such as walking, bicycling, and transit had always been popular in the university and college campuses around the United States despite the domination of automobile-oriented transportation since post-World War II [1
]. The LCT has been, however, receiving renewed attention in higher education campuses since the beginning of 21st century [2
] as a mechanism to reverse CO2
emissions from auto-dominated commuting [5
]. Automobile transportation dependents on fossil fuels is the primary sources of CO2
emissions and is growing at faster rate than any other energy sector in the United States [8
] mainly due to the unlimited desire for personal mobility [9
]. As part of the reversion process, a descent investment in LCT infrastructures has been ongoing not only in American college and university campuses, but almost in every urban areas of the United States [5
Understanding university students’ commuting behaviors is steadily growing as well [14
]. University communities that are built by incorporating LCT infrastructures, housing affordability and mixed land-uses promotes travel benefits including lower automotive drivers [16
] and higher LCT users [7
]. These studies, however, warned that the successful implementation of low-carbon transport transition requires the careful consideration of the specific contextual factors such as socio-cultural features of the examined campus and the corresponding urban built-environment and transport network [18
]. Given the fact that the passenger transport must needs to be decarbonized sooner than later to reverse greenhouse gas emissions (GHG) [20
] from university campuses, further research is warranted for a deeper understanding of students’ commuting behaviors.
There is, yet, a lack of research in examining students’ low-carbon mode choice in a commuter university campus [21
], especially by using knowledge learned from different disciplines [22
]. Commuter universities are different in many aspects, such as they may have a diverse range of student population, including traditional (recent high school graduates to age 24) and non-traditional (25 years or older), holding full-time or part-time jobs, and or may even raise a family. Each of the demographic groups has preferred transportation modes resulting in complex travel patterns. These students are also part of the transportation system and urban structure that may have inadequate infrastructure for using alternative modes (e.g., [23
]). Students in commuter campuses tend to have lower share of bicycle and walking commuters to campus than universities located in college towns [14
]. Hence, our case study intends to contribute in the literature by combining a suite of variables relating to students’ commute collected at University of North Carolina at Greensboro (UNCG) campus. The campus adopted a sustainability policy and Climate Action Plan to achieve zero net GHG emission goal by AD 2050, part of the American college and university campuses (ACUPCC) sustainable initiative [24
]. The results of this research can be directly beneficial to strengthen policy and implementation of strategies aiming at promoting low-carbon transportation behavior at this university or any similar kind of places even after an individual owns a car.
5. Discussion and Conclusions
This case study examines geographic variation of students’ low-carbon transportation (LCT) choice to a commuter campus by integrating a suite of variables developed in multiple disciplines. The LCT mode shares are impacted by various physical, demographic, and psychological dimensions. First, while physical environments are the most important factors for walk and transit commute, bicycle commute is not dependent on such factors. Distance (1.61 km from campus) either perceived or real is the most important factor for walk commuter, while transit ridership is most likely increases if students live >8 km from UNCG campus with nearest bus stop within 1 km from home. Sidewalk ratio, as well as the increase in distance from bus stops, increase the odds for walking. The later factors suggest that students rather walk to campus if distance between home and bus stops are more than 1 km. In contrast, bike score or bike lanes do not have significant impact on bicycle commuters, nor the distance from the campus. This is consistent with Zhou’s [14
] finding suggesting no correlation between commute distance and students’ biking to UC–Los Angeles. Given the limited bicycle lanes in Greensboro, this is no surprising. Students who commute to campus by bicycle are resilient to unfavorable bicycle condition by sharing the road with car and adjusting their travel routes [56
]. Solo-auto driver most likely increases 15 times in commuter zone 5, where no bus service is available and the area is outside 8 km from campus, while less likely decreases in zone 1. Clearly, the relationship between the built-environment and solo-driving and built-environment and walking have opposite effects.
Second, while socio-demography has no significant impact on walk mode choice, bicycle commuting is heavily impacted by such factors. Self-identified white students are 200% more likely to ride a bike and 75% less likely to take transit to campus. Car ownership has a negative impact on both bicycle and transit mode shares, but not for the walking mode choice since walking is heavily dependent on the 1.61 km distance threshold. While race does not make any difference on solo driving commuters, car ownership increases the greatest likelihood of such commuters that include carpooling. Our findings are in line with past studies that identified cycle commuters are more likely white middle class [68
], and bus riders are low-income non-whites in the USA [54
Third, psychological factors, such as perceptions, motives, habits, beliefs and attitudes have a significant impact on LCT. While we could not include perceptive zones in our models for logistic purposes, our cross-tabulation analysis and walking model (not presented in the Results section) with perceived zones show that students walk greater distances if they perceive that they live within 1.61 km from campus. Our research finds that not only the actual distance, but also people’s perceived distance has an impact on walking and bicycling [36
]. While safety concerns about street crossing decrease the odds of walkers, there is no significant impact on such a perception of space for bicyclers. Habit is an important factor for mode choice. For example, having a walking habit increases the likelihood of walking. Students who are habitual walkers for meeting transportation needs are more likely commute to campus by walking. In contrast, the decision to cycle every day is affected by the direct benefit factor [55
]. For example, our findings suggest that bicycle commuters are motivated heavily by their willingness to remain physically active or the joy of riding it [56
]. The odds of both bicycle and transit commuters decrease if individuals have to carry many things and the perception about a car as a necessity for faster mobility needs increase.
Fourth, while this research does not compare transportation modal shares between university towns vs. commuter urban universities, underrepresentation of cycle and transit commuters in the study sample might be an indication of lower share of bicycle and transit commuters at UNCG. Additionally, given the distance from campus is the most important factor for the share of LCT mode, which is consistent with earlier mode-choice research, it is not unlikely that a commuter university like UNCG will have a lower level of LCT. Most importantly, this research supports that perceived space and faster mobility necessity are more influential than actual distance and mobility needs [31
]. Similarly, this research supports the self-selection hypothesis, which demonstrates that students can locate closer to campus if they prefer to LCT mode.
Fifth, given that the majority of our participants are female, and the small sample size for bicycle and transit users, our models have some limitations in this study. Some important variables did not enter in the models due to their insignificant relationships with LCT, but we think this is because of the small sample size. Therefore, they are worthy of discussion. For example, unlike past studies (e.g., [15
]), our analysis did not give an indication that being female, or more bicycle and pedestrian accidents are associated with lower level of LCT mode shares. A higher population density seems to make slightly positive differences in the walk mode, but shows negative association with the bicycle mode. These variables should be considered seriously for further study with larger sample sizes because of their direction of relationships in our analysis. Similarly, pro-environmental behaviors seem to slightly positively affect the LCT mode. Further, this research did not collect data for students’ year at college (e.g., sophomore, freshman, senior. etc.). We think the length of time students have been in college affects their familiarity with the area, as well as the degree to which they have been exposed to diverse social, political, and environmental ideals, which may impact the mode choice. Our research also did not have data about the time of students’ classes, or destinations after classes. These variables should be considered seriously for further study.
Finally, although this analysis has limitations, the results presented here have important implications for commuter campuses, like UNCG or non-student communities. While energy-saving technologies, such as electric or hybrid cars, can play an important role in transitioning to low-carbon transport, it may not be realistic to expect to address the challenge of CO2
emissions rapidly enough with this technology [72
]. Alternative-fuel vehicles (AFVs) are already established in the market, but refueling infrastructure for these types of vehicles is still in its initial stage in most places and has limited consumer acceptance [73
]. Even though a new AAA survey finds 20% of Americans thinks their next vehicle will be an electric car, most Americans cannot afford a new car [74
]. While zero emission car development technology may be environmentally beneficial, at the same time it may contradict transport equity due to the issue of affordability [75
]. We also acknowledge that it is not realistic to change travel behavior rapidly to reduce car usage in the United States, but college campuses have populations that are acceptable to the idea of LCT. Therefore, commuter universities can greatly increase the use of LCT on their campuses and in their surrounding communities. Investment in LCT will not will decrease the CO2
emissions, it will also decrease the socio-spatial inequalities associated with automobile and increase public health benefits, such as a reduction in mortality and morbidity [76
There are many opportunities for commuter universities to build communities for low-carbon travel behaviors. For example, universities can partner with cities to build affordable housing with mixed-land uses targeting students within 2 km of campus to make zero car use zone. Improving the bicycle network and public transit with zero emission buses with integrated land use and close proximity to bus stops can reduce many negative externalities of automobile mobility for individuals living beyond 2 m from campus [77
]. Our findings strongly support Greensboro’s current initiative “Mobility Greensboro 2040” and “Vision Zero” planning and policy initiatives for enhancing equitable and safe transit-oriented multi-modal infrastructures [60
]. There is considerable agreement in the literature and our findings reiterate cities that build with a mixed-land use, transit accessible, well-connected street network with good sidewalks encourage higher levels of LCT mode shares for the entire populations. Therefore, the “Vision Zero” program will not only enhance the LCT mode for the UNCG students, it also can encourage non-student populations to utilize LCT modes. Universities often play a major role in expanding the quality of the local economy and cultures, hence, we suggest that UNCG should utilize its influence to advocate and further facilitate these ongoing efforts by partnering with local transportation and planning stakeholders.