I would say that it was the tracking of the vehicles. The tracking centre seems to be what a lot of the studies are focused on at the moment. Vehicle slowdown is also a future federal requirement. They have provided money to these companies to start implementing that in the hope that trucking companies will comply and they won't be forced to mandate, or once they have mandated, most trucking companies will have complied with vehicle shut-down and GPS tracking.
On March 5th, 2009. See this statement in context.