1. A vision system for a vehicle, said vision system comprising: a forward facing camera configured to be disposed at a windshield of a vehicle equipped with said vision system, wherein, when disposed at the windshield of the equipped vehicle, said forward facing camera has a forward field of view through the windshield of the equipped vehicle; said forward facing camera comprising an imaging array sensor and a lens; wherein said forward facing camera is operable to capture image data for an adaptive speed control system of the equipped vehicle; an image processor operable to process captured image data; wherein, responsive at least in part to processing by said image processor of captured image data, lane markers of the road along which the equipped vehicle is traveling are detected; wherein, responsive at least in part to processing by said image processor of captured image data, other vehicles exterior the equipped vehicle are detected; wherein, responsive at least in part to processing by said image processor of captured image data, road curvature of the road along which the equipped vehicle is traveling is determined; wherein, responsive at least in part to processing by said image processor of captured image data, entering of the equipped vehicle into a road construction zone is determined; and wherein, responsive to the determination, at least in part by processing by said image processor of captured image data, that the equipped vehicle is entering into the road construction zone, speed of the equipped vehicle is automatically reduced without the driver having to manually deactivate the adaptive speed control system of the equipped vehicle.