Driver's License Test Prep
Pennsylvania Practice Traffic Lights

You are stopped at a single-lane on-ramp controlled by a ramp-metering signal. When the light turns green, how many vehicles may enter the highway?

  1. A.
    All vehicles queued behind the line
  2. B.
    Two vehicles per green
  3. C.
    Only one vehicle per green Correct
  4. D.
    As many as fit in a safe gap
The Why

The answer is "Only one vehicle per green"

On a single-lane ramp meter, one car enters the highway per green, then the light returns to red to space arrivals onto the mainline. Drivers drawn to A treat the metered green like an ordinary intersection light, where the whole queue keeps rolling until the cycle turns.

Why the others miss

The traps in the wrong answers

A. All vehicles queued behind the line

The green does not clear the queue; only one car proceeds per cycle. This answer treats the metered green like an ordinary intersection light, where the whole queue keeps moving until it cycles back to red.

B. Two vehicles per green

The single-lane rule releases one car per green, not two. This answer half-remembers the multi-lane rule (one meter head per lane) and averages it to two cars per green by picturing a typical two-lane on-ramp.

D. As many as fit in a safe gap

That describes a normal yield-and-merge, not a metered release. This answer reads the manual's reminder to still find a safe gap as permission to slip a second car through behind a leader on the same green.

The Rule

This question tests your knowledge of Traffic Lights in Pennsylvania. Source: Pennsylvania Driver Manual, "RAMP-METERING SIGNALS," p.8..

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