Evaluating the applicability of HCM-7 travel time reliability metrics in an emerging urban context: A case study of a single arterial corridor in Morelia, Mexico

Travel time is a fundamental metric for evaluating the performance of urban roadway networks. However, its measurement often relies on surveys or post-processed GPS trajectories, which can be both costly and time-consuming. Moreover, existing methodologies for assessing travel time reliability in urban settings remain limited and are often difficult to implement in developing regions due to differences in infrastructure, urban form, and driver behavior. One of the most widely adopted frameworks is the methodology presented in the Highway Capacity Manual, Seventh Edition (HCM-7), which uses a deterministic base modeling structure combined with stochastic scenario generation through Monte Carlo simulation and standardized indicators to estimate travel time variability. This study presents a comparative analysis between the outputs of the HCM-7 methodology and empirical travel time data derived from digital mapping services such as Google Maps. The case study focuses on a 2.0 km four-lane arterial corridor with fourteen signalized intersections in the city of Morelia, Mexico, where travel time data were collected during weekday morning and afternoon hours from April to July 2025. Key reliability metrics, including the Planning Time Index (PTI), Buffer Index (BI), and Travel Time Index (TTI), were evaluated. The results reveal notable discrepancies between the modeled outputs and the Google Maps estimates, highlighting systematic differences between model-based and probe-based estimates and underscoring the importance of context-sensitive calibration to improve agreement. Future work should focus on calibrating adjustment factors and scenario-generation parameters within the HCM framework to better capture observed travel time variability.