How urban street-scape visual features influence carbon emissions from residents visiting urban parks: A case study of Shenzhen, China

The share of carbon emissions in the transport sector has been increasing year by year, and how to optimise the urban environment in order to promote green and low-carbon travel for residents has become a research hotspot. Much of the existing research has focused on the environmental characteristics of trip origins and destinations, with less attention paid to the impacts of the built environment in the travel path. This study takes Shenzhen, a megacity in China, as a case study to investigate the impact of street environment characteristics on residents' green travel behavior to urban parks. First, we conducted a questionnaire survey among visitors to urban parks between March and May 2023, finally collecting a total of 3,970 questionnaires. Then, by extracting and analyzing 137,000 street view images, we extracted street characteristics such as the green view index, sky openness index, sidewalk proportion, and wall coverage on respondent’s traveling road to urban parks. These street features were combined with visitor’s socio-demographic data, urban park’s characteristics, and other urban built environment to construct a generalized ordered logistic regression model. The results indicate that street greenery and sky openness are key factors contributing to low-carbon travel (Std=-2.886, p=0.000***; Std=-2.249, p=0.004***). In 2023, the total visitor volume to 176 urban parks in Shenzhen reached approximately 492 million visits, generating a total travel-related carbon emission of about 41,300 tons. The carbon emissions exhibited significant spatial variations, with higher emissions observed in coastal areas such as Nanshan District and Futian District. Additionally, there was a decreasing trend in carbon emission intensity from west to east. Based on the findings from travel mechanism studies, we proposed three different scenarios of low carbon development, including scenario of transportation system optimization with Shenzhen's public transport modal share reaching 65%, scenario of energy efficiency improvement with new energy vehicles accounting for 40% of the fleet, and scenario of street environment enhancement with the green visibility increased to 0.18. It found that these three scenarios would contribute to carbon emission reduction by 27%, 17%, and 4%, respectively. Even if the improvement of the street built environment does not provide the highest carbon emission reduction, it still has high potential for low-carbon development in high-density populated cities. This study reveals the critical role of the built street environment in promoting low-carbon travel and provides new methods and empirical support for low-carbon urban planning. Additionally, through future scenario analysis, this research offers scientific evidence for developing adaptive policies aimed at reducing carbon emissions.