The BEST way to report a bad truck driver is to get a window mount for your smart phone and video them, use your voice to record the details of the event. On the video recording with your voice, grab the truck's license plate and fleet number if you can, see if there is a carrier/company name on the truck. Make note of the time of day, which roadway and mile marker you are at. The more info you can safely get, the easier it will be for the company to figure out exactly who was driving.
After you have the Video with your voice on it filling in all the details of the incident, call the company, tell them you have a details video and voice report want them to take action against the driver of the truck. Tell them you WILLpost the video on YouTube unless they prove to you that the driver has been punished for driving dangerously.
Note: If these videos are posted online that company will be known for hiring "drivers that drive like teenagers!