A driver’s legal limit is set because alcohol impairs the abilities needed to operate a vehicle. The widely used per se limit is 0.08% BAC; at or above this level, reaction time slows, coordination suffers, and judgment is impaired, making driving legally unsafe and unlawful in many places. That’s why 0.08% BAC is the threshold you should know. 0.10% is simply a higher level of impairment and would also be illegal, but the standard threshold most often tested is 0.08%. A BAC of 0.05% is below the common legal limit in many jurisdictions (though impairment can occur earlier for some people), so it isn’t the typical cutoff. A BAC of 0.00% means no alcohol is in the blood, which is legal to drive.

Prohibition signs use a red circle to show something isn’t allowed. When the action is a turn, the arrow shows which direction is affected, and a cross over that arrow marks the ban. Here, the right-turn arrow has a cross, so turning right at that sign is not allowed. You should either go straight or, if permitted by other signs or rules, turn left. If it were a left-turn ban, the cross would be on the left-turn arrow; if right turn were allowed, there wouldn’t be a cross; a No U-turn sign would show a U-turn symbol with a cross.

When you’re behind a large vehicle with limited visibility, the priority is to increase your following distance. Large trucks and buses have big blind spots and can’t see well to the sides or directly behind them. If you’re too close, you may not be seen and you won’t have enough time to react if they brake suddenly, stall, or encounter a hazard. By staying back, you gain a clearer view of the road ahead, you can see brake lights and signals sooner, and you have more time to react, which reduces the chance of a rear-end collision. In practice, give yourself extra space—often a four-second or greater separation is wise, especially in rain, fog, or at higher speeds. If you can’t see the truck driver’s face in their side mirrors, you’re likely in a blind spot and should wait to pass or adjust your position. Other choices would put you closer to the vehicle, keeping you in its blind spots or reducing your time to react, and stopping in intersections can block traffic and create danger for everyone.

When someone behind you flashes their headlights, it’s a cue that you’re holding up faster traffic. The safest move is to get out of the way by signaling and moving to the right or pulling over when it’s safe so they can pass. This reduces the risk of a tailgating crash and keeps traffic flowing smoothly. Avoid speeding up or braking abruptly to “test” the signal; those actions can create a dangerous situation and won’t help the situation.

Reading route markers is about matching the route number with the direction and following the arrow that shows how to reach that direction. In this sign, you see Route 22 with West and an arrow pointing to the right. That combination tells you that to head west on Route 22 you must turn right now. The number identifies the highway, the word West shows the direction along that highway, and the arrow indicates the exact turn to take to join the westbound route. If you went left, you’d be heading onto a different direction or road; going straight would leave Route 22 entirely at this point; and a sign saying the route ends would look different, signaling an end rather than the continuation of Route 22 West.