The main objective of this paper is to provide a concept of “Level of Acceptance (LOA)” as a measure of traffic congestion at congestion flow conditions when speed drops lower than the critical value (i.e., speed at maximum flow). Among the widely applied measures of congestion, speed “u” is found to be the best measure of congested flow. A questionnaire survey for congestion acceptance choices was conducted among drivers (public and transportation Eng. Professions) in Abu Dhabi Emirate. The Explanatory and Conformity Factor Analysis showed that three different levels of congestion can be recognized based on drivers’ perspectives. The thresholds of these levels are 25% and 65% speed drop values from the critical speed reference. The statistical tests showed that drivers' characteristics have not significant impact on the classification or the thresholds of the developed congestion levels except their nationality which may related to the drivers’ congestion background experience at their original countries. A case study analysis of a freeway with a 140 kph speed limit is employed as a practical example. The range of the speed thresholds of the three congestion levels on this road are for Level I “Fo” occurs at speeds between 105 and 79 kph, Level II “F1” speeds between 79 and 37 kph, and Level III “F2” speeds lower than 37 kph. The corresponding density k and v/c values have been estimated (as surrogate measures) from the traffic flow parameters relationships.