Many cities suffer from traffic congestion, but physical expansion of roads is often infeasible in urban areas. A solution in such circumstances is to build underground roads, which involves adding new lanes beneath existing roads or other facilities. This study explores route choice behavior on a 10 km stretch of an urban expressway where both underground toll lanes and ground-level free lanes are available. Real-time travel time information for each route is provided via variable message signs (VMS) for informed choices. We collected revealed preference data by taking videos at the entrance of two alternative routes in Seoul. The study analyzed 142,045 trips and found that overall 35 percent of those trips chose underground toll lanes. The share of drivers choosing underground toll lanes tends to be higher during peak hours compared to non-peak hours or weekends. By using the mixed logit with interaction effects, we found that there are meaningful heterogeneities in the sensitivity to travel time and thus the value of travel time (VOT) affected by temporal characteristics. Drivers generally have higher VOTs on Fridays, followed by other weekdays, and then weekends. In addition, people are more willing to use underground toll lanes during peak hours than during non-peak hours. The traffic count variable (a proxy for congestion level) has a positive coefficient, indicating that higher congestion levels are associated with a stronger preference for underground routes. After controlling for travel time, cost, and temporal effects, the alternative-specific constant is negative, which signifies that, ceteris paribus , drivers tend to prefer the ground-level option over the underground option. We also explored optimal pricing by accounting for time-dependent traffic volume and VOT. Overall, this study deepens our understanding of underground toll lane choice behavior and potentially suggests implications for pricing and lane operations.
Kim et al. (Wed,) studied this question.