Bridges matter: Modeling joint bridge and route choice equilibrium with bridge-centric choice set generation

As a critical infrastructure in the road network divided by rivers, bridges are an inevitable consideration in traveling between disjointed network sections. Despite the increasingly recognized importance of bridges in routing, the perception and choice of bridges have not received enough attention in travel demand modeling, such as the widely used stochastic user equilibrium (SUE) traffic assignment (TA) model. This study develops a joint bridge and route choice equilibrium model to account for various behavioral issues stemming from the bridge choice dimension. The perceived availability of bridges owing to their spatial relationships with origins and destinations is specifically considered in both bridge set formation and bridge choice behavior from the perspective of travelers. The interaction between bridge and route choice dimensions is modeled via a hierarchical choice structure. The network equilibrium is modeled consistently with joint bridge and route choice behavior and formulated as an equivalent mathematical programming problem. To facilitate the application of the proposed equilibrium model in bridge networks, we develop a bridge-centric choice set generation strategy with a multi-stage column generation algorithm that can effectively employ properties of bridges and routes. Numerical experiments are conducted to demonstrate the applicability of the proposed model and choice set generation strategy in a real-world setting. The model’s tested performance underscores its potential as a policy instrument for informed decision-making in the assessment and management of bridge networks.