An Integrated Land-Air Mobility Network Equilibrium Model with Park-and-Ride

With the rapid development of Urban Aerial Mobility (UAM), electric Vertical Take-Off and Landing (eVTOL) aircraft are poised to become an important mode of transportations for commuters. Traditional traffic assignment models, primarily based on two-dimensional road networks, struggle to accurately characterize the the three-dimensional path structures and intermodal transfer behaviors introduced by eVTOL operations. This limitation challenges in route choice, travel impedance calculation, and network equilibrium modeling for conventional traffic assignment frameworks. To address these issues, this study proposes a land–air collaborative network equilibrium model that incorporates Park and Ride (PR) behavior, aiming to comprehensively analyze travelers’ mode split and route choice travel impedance calculation. Considering the substantial overlap between PR and other travel modes, a Cross-Nested Logit (CNL) model is adopted to capture the similarities among different travel modes. Concurrently, an M/M/1/C queueing model is used to describe the queuing characteristics at vertiports. Building upon this, expressions for various segment impedance functions are formulated. For model solution, an iterative framework based on an improved Gradient Projection (iGP) algorithm is constructed. This framework jointly addresses mode split and traffic assignment, ultimately achieving a state of user equilibrium. Numerical experiments conducted on the Sioux Falls network verify the effectiveness of the proposed model and algorithm. Results indicate that when PR-based mode choice is considered, over 30% of travelers are attracted to adopt eVTOL services, substantially influencing the network equilibrium outcomes and traffic flow distribution. The findings of this study provide valuable insights for the future coordinated development of UAM and ground transportation systems.