A Cross-Boundary Travel Tale: Unraveling Hong Kong Residents' Mobility Pattern In Shenzhen By Using Metro Smart Card Data

The development of transportation networks has constantly increased the cross-boundary flow of people, logistics, and capital. However, when the cross-boundary flows span two regions with different political systems, cross-boundary mobility studies become difficult to perform due to the unavailability of reliable and direct research data. Consequently, in-depth and fine-scale cross-boundary mobility studies remain lacking. With the aid of a smart card dataset, this paper proposes a new framework to break the deadlock in cross-boundary travel behavior studies. Drawing on a 35-day Shenzhen smart card dataset, our study aims to unravel the Hong Kong cross-boundary travelers' mobility patterns in Shenzhen on the basis of the assumption that some Hong Kong cross-boundary travelers who travel through checkpoints to Shenzhen hold a Shenzhen metro smart card to use the Shenzhen metro system easily and rapidly. Through this assumption, we develop a method for identifying travel by Hong Kongers visiting Shenzhen. To our best knowledge, this study is the first to use emerging big data to explore a fine-scale cross-boundary travel behavior between Hong Kong and mainland China. The research results can be summarized in two aspects. (1) Temporal features: Hong Kongers mostly prefer weekends and afternoon periods (11 a.m.-6 p.m.) to travel to Shenzhen, but they have a considerably low cross-boundary travel frequency (54.5% travel only once in 35 days). When they are traveling in Shenzhen, they usually take only two metro trips, spending approximately 15 min in the subway; their duration in Shenzhen is approximately 4.5 h on weekends, and is slightly longer on holidays (5.02 h) and shorter on workdays (4.09 h). (2) Spatial features: some Hong Kongers tend to take Shenzhen as the transfer stop for going to other cities. The travel spatial scope of Hong Kong cross-boundary travelers is almost confined to the center area of Shenzhen. They prefer to travel to nearby and mature business districts well equipped with commercial service facilities, such as Laojie, Guomao, Shopping Park, and Grand Theater.