Comparing Light Rail and Bus Semirapid Transit on a Level Playing Field: A Model Oriented to Ex Ante Evaluation Under Uncertain Conditions

Abstract

[Abstract]: Light Rail Transit (LRT) and Bus Semirapid Transit (BST) are two different forms of semirapid, medium-capacity transit systems. Over recent decades, there has been an ongoing, unresolved debate on which of these two technologies brings about a higher net contribution to a society’s welfare. This study seeks to shed light on this topic through the design, development, and computational execution of a model specifically devised for forecasting transport-related outcomes that would result from the implementation of either an LRT or BST system in a given corridor. This model dynamically systematizes the mutual interactions between travel demand prognoses, the supply attributes of a typical set of modal alternatives, the valuation of those modal alternatives from travelers’ perspectives, and travelers’ consequent choices, taking into account the specific differences between LRT and BST. Furthermore, the model incorporates a methodological treatment of uncertainty through the application of Monte Carlo random simulation techniques. In practice, the model is applied to a case study based on artificial data representative of usual conditions seen in corridors with enough ridership to consider these transit systems. The specific results indicate that LRT generates a moderately higher benefit for travelers in these circumstances, but this turns into a very slight advantage for BST when the investment costs are deducted. Ultimately, this research will contribute to better-informed decision making when selecting a semirapid, medium-capacity transit system, leading to more efficient budget allocation.