ABSTRACT Level of service (LOS) classifcations of traffc oper- ational conditions play a signifcant role in roadway-im- provement funding decisions. Traveller perception of LOS should be consistent with traffc analysis values to avoid undermining the public confdence in the transpor- tation agency decisions. Research methods to study trav- eller perceptions range from in-vehicle videos to focus groups and surveys. These methods have different advan- tages, but all suffer from time and/or cost ineffciencies for collecting data sets across a wide range of operating conditions. This paper describes a novel method to study this topic with increased time and cost effciency. This new method combines traffc microsimulation and 3-D visualisation capabilities. The focus of this paper is to provide guidance on how to apply traffc microsimula- tion and computer 3-D visualisation to evaluate highway trip quality from a traveller’s perspective. It discusses the creation of the simulation environment to produce a real- istic view from the vehicle’s cabin interior, including the network creation, landscaped area, dashboard speedom- eter, and rear-view mirror. The authors also propose an automated method for choosing an appropriate vehicle within the simulated traffc stream, such that the desired overall traffc stream conditions are conveyed to the trav- eller vehicle within the feld of view. KEYWORDS computer 3-D visualisation; traffc level of service, traffc conditions perception; traffc microsimulation; automated vehicle selection method. 1. INTRODUCTION The concept of level of service (LOS) was in- troduced in the second edition of the Highway Ca- pacity Manual (HCM), in 1965 [1]. LOS refers to assigning a letter grade (from A, the best, to F, the worst) that corresponds to the general operational conditions, as measured by one or more perfor- mance measures, referred to as service measures. In the 1965 HCM, the selected service measures for freeways were operating speed and volume-to-ca- pacity ratio [2]; in the third edition of the HCM, released in 1985 [3], basic freeway segments were assessed for the frst time, with density chosen as the service measure [2], which was kept in the sub- sequent editions. While the service measures and thresholds for LOS rankings have historically been chosen by transportation engineers involved in the develop- ment of the HCM, the intent is that these ranking thresholds would also be reasonably consistent with how the travelling public would perceive the quality of the operational conditions. Given the very large amount of funding typically involved in transporta- tion infrastructure decisions, it is vitally important to transportation agencies that there be consisten- cy between the quantitative changes to the opera- tional conditions as a result of the investment and the perception of these changes by the users of the Piva FJ, Setti JR, Washburn SS. Using Traffc Simulation for Level of Service Traveller Perception Studies USING TRAFFIC SIMULATION FOR LEVEL OF SERVICE TRAVELLER PERCEPTION STUDIES Traffc Engineering Original Scientifc Paper Submitted: 16 July 2021 Accepted: 15 Oct. 2021 Promet – Traffc&Transportation, Vol. 34, 2022, No. 2, 297-308 297 Fernando José PIVA, M.Sc. 1 (Corresponding author) E-mail: fjpiva@usp.br José Reynaldo SETTI, Ph.D. 1 E-mail: jrasetti@usp.br Scott S. WASHBURN, Ph.D., P.E. 2 E-mail: swash@ce.uf.edu 1 Department of Transportation Engineering São Carlos School of Engineering University of São Paulo Av. Trabalhador São-carlense, 400, São Carlos, SP, 13566-590, Brazil 2 Department of Civil and Coastal Engineering University of Florida 365 Weil Hall, Gainesville, FL 32611-6580, USA