Pennsylvania CDL Practice Exam 2025 – Your Comprehensive All-in-One Guide to Exam Success!

The correct answer indicates that slow-moving vehicles and those operating under a specified speed limit are typically prohibited from using the left lane on highways. This regulation exists for safety and efficiency reasons. The left lane, often referred to as the passing lane, is intended for faster-moving traffic. When slow-moving vehicles occupy this lane, they can impede the flow of traffic, leading to congestion and potential safety hazards, as drivers may be compelled to make unsafe lane changes to pass these vehicles.

In many jurisdictions, laws are in place to enforce this traffic regulation, ensuring that vehicles traveling significantly below the normal speed limit remain in the right lane. This helps to keep the left lane clear for overtaking and faster-moving vehicles, thereby enhancing overall traffic flow and reducing the risk of accidents caused by sudden lane changes or backlogs of slower traffic.

The other choices, while relevant to lane usage, do not accurately reflect the specific prohibition regarding slow-moving vehicles. Passenger vehicles and heavy-duty trucks can generally use the left lane when traveling at appropriate speeds. Emergency vehicles have specific operational protocols that allow them to use any lane as needed, especially when responding to incidents.