This paper is concerned with the impacts of lane-changing maneuvers in traffic streams. A new methodology is developed based on the simplified kinematic-wave theory and only requires one assumption: a constant speed of the backward-moving characteristic along a large platoon of vehicles. This method consists in quantifying the net impact of entering and exiting-lane changing maneuvers among a platoon of fifteen vehicles. It has been applied to two highway trajectory datasets from the NGSIM program. Findings from this study show that the impact of lane-changing depends on the net number of entering vehicles to a lane, and insertions have greater impacts in traffic stream than exits.