Pennsylvania CDL General Knowledge study materials
Pennsylvania CDL General Knowledge study resources

Pennsylvania CDL General Knowledge: Seeing

Pennsylvania CDL General Knowledge · Work through your exam, one topic at a time.

All guide sections

Seeing

What the exam tests

Seeing covers visual search, following distance, mirror use, and blind spots. Questions ask how far ahead to look and how much space to keep.

Core rules

  • Look 12 to 15 seconds ahead of the vehicle.
  • Keep at least a 4-second following distance; use 7 seconds for heavy loads, bad weather, or darkness.
  • Check mirrors every 5 to 8 seconds.
  • Know your blind spots and do not linger in others' blind spots.
  • At night or in poor visibility, reduce speed so you can stop within the distance you can see.

Worked example

At 55 mph, a 4-second gap is about 323 feet. That is roughly the length of a football field including the end zones. If the road is wet, the same speed needs more than 4 seconds because stopping distance grows. The reasoning is that following distance is measured in time, not fixed feet, so it scales with speed and conditions.

Traps that cost marks

  • Staring at the vehicle ahead instead of scanning far down the road.
  • Changing lanes without a mirror check and shoulder glance.
  • Keeping a 4-second gap in rain when 7 seconds is needed.
  • Forgetting that large vehicles have deep blind spots on both sides and behind.

Exam tip

Time-based following distance is the exam's preferred measure; fixed car lengths are not.