Which of the following is NOT part of a motorist information system?

A motorist information system is designed to provide drivers with real-time information that helps them make informed decisions while navigating. This system typically includes elements that alert drivers to current traffic conditions, guiding them to optimize their routes and improve safety. Variable message signs display important information such as traffic congestion, construction updates, or accidents. In-vehicle guidance utilizes technology within vehicles to assist drivers with real-time navigation and alerts. Radio messages can serve to broadcast important traffic updates and warnings to the public.

Ramp metering, while a traffic management strategy that controls the flow of vehicles onto highways to prevent congestion, is not primarily considered a part of a motorist information system. It primarily focuses on controlling vehicle entry to maintain optimal flow on the highway rather than providing ongoing information directly to motorists. By controlling how many vehicles can enter the freeway at a time, it influences traffic dynamics but does not offer the type of direct informational assistance that the other options do.