Evaluation of Perception and Nonperception based Approaches for Modeling Urban Road Level of Service

• Published in: Journal of the Institution of Engineers (India). Series A, Civil, architectural, environmental and agricultural Engineering Civil, architectural, environmental and agricultural Engineering, 2022, Vol.103 (2), p.467-480
• Main Authors: Raj, Jithin, Vedagiri, P.
• Format: Article
• Language: English
• Subjects: Civil Engineering; Cluster analysis; Clustering; Engineering; Evaluation; Intersections; Manuals; Modelling; Original Contribution; Perception; Perceptions; Roads; Roads & highways; Thresholds; Traffic speed; Vector quantization
• ISSN: 2250-2149; 2250-2157
• DOI: 10.1007/s40030-021-00602-4

As road-user perception has become an essential component in level of service (LOS) analyses, the current study attempts to evaluate and comprehend the urban road LOS using two approaches, perception and nonperception. The study has used percent free-flow speed (PFFS) as the service measure, similar to the existing manuals. In addition, for the realistic evaluation of both approaches and to account for the frequent signalized intersections present on the roadways, the analysis evaluated urban roads as segments with multiple intersections. The nonperception-based approach utilized speed profile data from various operating scenarios and employed the k -means clustering technique for classifying and arriving at the LOS thresholds. Whereas in the perception-based approach, responses from the travelers were collected through video laboratory sessions by showing sample video clips of urban road travel. Ordered logistic regression is implemented for modeling these responses to derive the service level thresholds. The subsequent investigation revealed that the thresholds from the nonperception approach resembled the thresholds defined in existing manuals, compared to the perception approach. The study also found that urban road travelers are more tolerant of congested conditions, evidenced by a 3% decrease in perception-based thresholds. In contrast, the perception-based thresholds for the stable and free-flow conditions were incremented by 3–6% and 10%, respectively, than the nonperception approach. This suggests that perceptions of urban road travelers do not correspond with the existing PFFS thresholds that define urban road LOS. Hence, the comparative analysis presented in this paper will contribute to the efficient evaluation and planning of urban roads by examining the perceptions of both engineers and travelers.