Which of the following blocks the smooth flow of traffic?

1. Slowing down to look at collision scene. ✓
2. Avoiding unnecessary lane changes.
3. Using public transportation instead of your vehicle.

Answer: A. Slowing down to look at collision scene.

Slowing down to look at a collision scene blocks the smooth flow of traffic.

Why this is the answer

The manual's speed section explains that traffic moves best when vehicles keep up a steady pace, and that driving too slowly can hold up the cars behind you and create a dangerous condition. A driver who brakes to stare at a crash does exactly that: the speed drops for no reason tied to the road ahead, and the line of traffic behind bunches up. Keeping your attention on your own path and your speed reasonable for conditions is what keeps flow steady.

Why the other answers are wrong

• B. Avoiding unnecessary lane changes. — Avoiding unnecessary lane changes helps traffic run smoothly, since staying put keeps other drivers from having to react and adjust.
• C. Using public transportation instead of your vehicle. — Leaving the car behind and taking public transportation removes a vehicle from the road, so it cannot be what blocks the flow of traffic.

Remember it

Ask yourself whether your speed matches the road ahead — if you are slowing for something that is not in your path, you are the hold-up.