Semi trucks aren't trying to calm traffic, they are maintaining a consistent speed (or rather engine RPM) and gear for fuel efficiency. Drivers are paid per mil

Semi trucks aren't trying to calm traffic, they are maintaining a consistent speed (or rather engine RPM) and gear for fuel efficiency. Drivers are paid per mile and the further they can go on a single fill-up is more money in their pocket. Edit to add: It is a computer telling them how fast to go, usually something similar to http://www.scangauge.com/ http://www.scangauge.com/