Congestion is bane and a persistent issue, especially in cities. It results in longer travel times, more fuel usage, and environmental pollution. Congestion occurs when traffic flow exceeds road capacity, which causes speeds to drop significantly below “free flow” or average speeds. 5G V2X allows ITS stations to exchange PSSCH that contains CAM. CAM carries vital information such as GPS coordinates and speed. Using this vital CAM information, this study developed a speed-based method dependent on a pre-defined threshold to identify congestion on roads more accurately. Results from simulation using real vehicle traffic traces indicate better congestion detection performance. There are more false detections based on time-gap as the performance measure as compared to speed. The proposed speed-threshold method achieved over 75% better detection results as compared to MCDP for long-term congestion detection.