Selection of a Suitable Service Measure and Determination of LOS Criteria for Indian Multilane Interurban Highways: A Methodological Review

Any transport facility is essentially a service being provided to the society. Therefore, it is expected of the traffic engineers, transport planners and policy-makers alike to be able to understand and evaluate the quality of service that is being provided by the transport facilities designed by them. The level-of-service (LoS) concept was devised in the US Highway Capacity Manual (US-HCM) precisely for the above consideration. However, direct implementation of the US-HCM methods in India is not possible because of the heterogeneous traffic conditions and vastly unique driver behavior found on Indian highways. Therefore, it becomes imperative to evaluate other competing methodologies that may be more appropriate in defining the LoS being offered to the road users by Indian highways in general and multilane interurban highways in particular. Towards this end, this paper reviews in detail the LoS estimation methodologies that have been demonstrated to be suitable for application in traffic scenarios characterized by high heterogeneity and lane indiscipline. Also, based on an exhaustive review of the literature, the study recommends that three to five categories of LoS in the stable-flow region may be explored for practical application in the Indian scenario as part of the ongoing research on development of an Indian Highway Capacity Manual.