Turn/lane-change signal100 feet before
Following distance2-second rule
Following — bad weather / trucks3–4 seconds
School bus stop distance20 feet minimum
No passing near RR crossing100 feet
No passing near bridge/tunnel100 feet
No passing — oncoming car within200 feet
Dim high beams (oncoming)Within 500 feet
Dim high beams (following)Within 200 feet
Headlights — visibility thresholdCan't see 1,000 ft ahead
Headlight hours30 min after sunset – 30 min before sunrise
RR crossing — stop distance15 feet minimum from tracks
Don't follow emergency vehicleWithin 500 feet (lights on)
U-turn — no visibility within500 feet either direction
💡 Two-second rule: pick a fixed object. When the car ahead passes it, count "one thousand one, one thousand two." Reach it before you finish the count = you're following too closely (MV-21 ch. 8, p. 47).