The phrases below have something in common. Can you determine what it is?

HINT:
It has to do with things you might see while driving.

1. Be liberal
2. Be conservative
3. Grading scale
4. Persevere
5. Kids in the theater
6. Quarterback's hope
7. 60-minute make-out limit
8. Kitty, you can't give birth here

Answers:

Each phrase can be expressed, more or less, in a common roadsign:

1. KEEP LEFT
2. KEEP RIGHT
3. CURVE
4. NO U TURN
5. CHILDREN AT PLAY
6. PASSING LANE AHEAD 
7. ONE HOUR PARKING
8. NO LITTERING

Credit:
Robert H. Wolfe
Chicago Tribune Sunday Puzzle
ROADSIGNS