TX Road Signs Cheat Sheet.
The night-before summary, built like the exam.

Move Over or Slow Down

Approaching a stopped vehicle with activated overhead lights: move over an entire lane, or slow to 20 mph below the posted limit.

• The reduction is relative. Posted 65 → 45. Posted 45 → 25. Posted 75 → 55. It is not a flat 20 mph.
• Covers law enforcement, tow trucks, utility vehicles, municipal waste trucks, emergency responders and TxDOT vehicles. Not just police.
• Since September 1, 2025: also animal control officers and parking enforcement employees.
• Activated overhead lights are the trigger. A disabled private car is outside the law.
• First offence up to $1,250. Serious injury: up to $4,000 and possible jail.

School buses — one exception

Stop for flashing red lights or an extended stop arm, whichever direction you are headed. Unless the bus is on the opposite side of a divided highway — then you may continue.

• An undivided two-lane road gives no exception. Stop.
• Whether children are visible is irrelevant.
• Proceed when the bus moves, the lights stop flashing, or the driver signals. The bus driver decides, not you.
• First offence up to $1,250 — the same ceiling as Move Over, because both protect someone outside a vehicle.

Speed — a two-step structure

• The statute sets a maximum of 70 mph.
• The Transportation Commission may set 75, 80 or 85 mph — but only where an engineering or traffic study finds the speed safe and reasonable and the highway is designed for it.
• So the answer to "what maximum does Texas law set" is 70, not 85.

Alcohol — three thresholds

• 0.08 ordinary limit.
• 0.04 commercial — attaches to the vehicle driven, not the licence held. Same person: 0.04 in a rig, 0.08 in their own car.
• Under 21: any detectable amount. No numeric floor. It is the criminal offence of Driving Under the Influence of Alcohol by a Minor. Texas defines a minor as anyone under 21.

Implied consent: driving is consent to chemical testing. Refusal suspends the licence on a separate track, so beating the charge does not save the licence. Only time lowers BAC — not food, water, coffee or exercise.

Right-of-way order

1. Four-way stop: first to arrive goes; a genuine tie yields to the right.
2. Turning left on a green ball: yield to oncoming traffic. The green permits the turn; it does not grant priority.
3. Intersection flashing red in all directions: treat as an all-way stop.

Signals

• Flashing red = stop sign.
• Steady yellow = red is coming; stop if you safely can. If you are already too close to stop without hard braking, continue through.

Signs and lines (national)

• Shapes are unique: octagon stop, downward triangle yield, diamond warning, pentagon school, circle railroad.
• Colours: orange work zone, blue motorist services, brown recreational and cultural. A yellow diamond and an orange diamond are the same shape at different urgency.
• Lines: white = same direction, yellow = opposing. Solid yellow on your side = no passing on your side.
• Following distance: three seconds in good conditions.