Effectiveness of Travel Time Reliability as a Measureof a Level of Service for Urban Roads

Level of service (LOS) is a measure that offers insights into the quality of service delivered by an infrastructure. Geometric parameters are typically considered as the measure of effectiveness (MOE) for LOS determination of roads. It is becoming increasingly important to consider user perception and experience to understand LOS. In this study, travel time reliability (TTR) is considered to measure user perception, which in turn is used to evaluate the LOS. TTR measures such as planning time index (PTI), planning time (PT), buffer time (BT), and buffer time index (BTI) are selected for study purposes. TTR measures are greatly influenced by traffic such as heterogeneous composition, and capture variations in traffic flow more effectively than the volume-to-capacity (V/C) ratio and average travel time. Among the TTR measures considered, the PTI was identified as a more suitable MOE compared to others. To incorporate multimodal user perception, two-wheelers, auto rickshaws, and cars, identified as the most widely used mode for urban roads in developing economies, requires separate classification. Simulation for study locations considering variation in geometry, and traffic flow up to 50% indicates sensitivity of TTR measures to such changes, providing insight into measures to improve users’ experience.