The development of the Internet of Vehicles makes it possible to exchange information between connected vehicles, or between connected vehicles and road network controllers. Therefore, it is very possible and promising to control the traffic flow by adjusting the speeds of some connected vehicles in the future. For this reason, in this paper we study the traffic flow evolution in a three-lane road after one vehicle in this road suddenly decelerates to a specific speed, where the following vehicles can independently operate car-following or lane change operations. Considering the availability of lane change operations is associated with the road traffic flows, we divide the model of the platoon length leading by the deceleration vehicle into two modes: 1) the platoon with a stable length; 2) the platoon with an increasing length. The stable platoon length and the growth rate of the increasing platoon are modeled, respectively, where their coefficients are identified based on the simulated data in SUMO simulator.