Sooner or later, every highway drive puts you next to an eighteen-wheeler.
Large trucks and buses move most of the goods and many of the people across the country.
They share the same lanes as your car, but they behave very differently.
A loaded truck is many times heavier than a passenger car.
It needs more room to stop, more room to turn and more time to change lanes.
Its driver also sits high above traffic with large blind spots on every side.
None of this makes trucks dangerous by default.
Most crashes between cars and trucks happen when a car driver misjudges what the truck can see or do.
This guide explains how big vehicles work and how to drive around them with confidence.
The rules come from the California Driver Handbook.
Other states teach very similar habits, so check your own state driver handbook too.
The No Zones: where the truck driver cannot see you
Truck drivers have a better view of the road ahead than you do.
They also have bigger mirrors on both sides of the cab.
Even so, a truck has large blind spots, often called No Zones.
The California Driver Handbook explains that your car can disappear completely from the driver's view in these areas.
It also gives one simple test you can use every time.
If you cannot see the truck's side mirrors, the truck driver cannot see you.
Here are the places where a car most often vanishes from view:
- Right beside the cab: especially on the right side, where the blind spot is larger.
- Directly in front: the hood is long and high, so a small car close ahead can be hidden.
- Directly behind: a trailer has no rear window, so a tailgating car is invisible.
- Alongside the trailer: long stretches next to the trailer can fall outside the mirrors.
The fix is simple. Spend as little time as possible in these areas.
When you must pass through one, do it steadily and move on.
Trucks need much more room to stop
Weight changes everything when it is time to brake.
The handbook says the average passenger vehicle traveling at 55 mph can stop within 300 feet.
A large vehicle traveling at the same speed can take up to 400 feet to stop.
That gap grows with weight and speed.
A loaded truck takes longer to stop than an empty one.
Truck drivers know this, so they try to keep extra space in front of them.
That open space is their safety cushion, not an invitation for you.
Never cut in and brake
The handbook warns against one move in particular.
Do not pull in front of a large vehicle and then suddenly slow down or stop.
The truck will not be able to stop fast enough to avoid hitting you.
This often happens near exits, when a driver squeezes in front of a truck at the last second.
If you missed a gap, it is far safer to take the next exit.
Why trucks swing wide on turns
When any vehicle turns, the rear wheels follow a shorter path than the front wheels.
On a car, the difference is small.
On a long truck or bus, it is large.
The handbook explains that this is why truck drivers often swing wide to complete a turn.
A truck turning right may first drift to the left.
It may also start its turn from the second lane, leaving an open space on its right.
Never pull into that space.
As the truck turns, the trailer sweeps back toward the curb and can crush a car caught there.
The handbook also advises checking a large vehicle's turn signals before you start to pass.
A truck may look like it is going one way while it is actually swinging out to turn the other way.
At intersections, stop behind the white limit line.
That leaves room for a turning truck or bus to clear the corner.
How to pass a truck the right way
Large vehicles are harder to maneuver than passenger cars.
They often travel in the right lanes, and on long climbs they may slow down.
When you need to get around one, follow a clear plan.
- Pass on the left side, where the driver can see you better.
- Signal early so the driver knows what you are doing.
- Move past the truck steadily without slowing down beside it.
- Wait until you can see the whole front of the truck in your rearview mirror.
- Signal again and return to the lane, then keep a steady speed.
The handbook lists several things to avoid near large vehicles.
- Changing lanes directly in front of them to reach an exit or turn.
- Driving next to them longer than you need to.
- Following too closely.
- Underestimating their size and speed.
That last point surprises many drivers.
Because a truck is so large, it often appears to be moving slower than it really is.
Give yourself more time and distance than you think you need.
Do not ride beside the trailer
Staying alongside a truck feels harmless, but it takes away the driver's options.
The handbook notes that driving alongside a large vehicle makes it hard for the driver to avoid dangers in the road.
If a tire blows or debris appears, the truck may need your space.
Either pass or drop back.
Following a truck
Staying close behind a truck is risky for two reasons.
First, the driver cannot see you.
Second, the trailer blocks your view of the road ahead.
You will not see brake lights, stalled cars or debris until the truck swerves around them.
Drop back far enough to see the truck's side mirrors.
Use at least a three-second gap, and more in rain, at night or on a downhill grade.
Our guide to the three-second rule shows how to measure it.
Where trucks are allowed to drive
Lane rules for heavy vehicles help explain what you see on the highway.
In California, trucks with three or more axles must use the far-right lane, or a lane marked for slower vehicles.
The same rule applies to anyone towing a vehicle or trailer.
On roads with four or more lanes in one direction, they may use only the two lanes closest to the right edge.
Expect slower, heavier traffic on the right.
When you merge onto a freeway, look carefully for trucks in the lane you are joining.
Our guide to merging and changing lanes covers that move step by step.
Placards and railroad crossings
Some trucks carry a diamond-shaped sign on the back and sides.
The handbook explains that this placard means the load may be dangerous, such as gas or explosives.
Trucks with these signs must stop before crossing railroad tracks.
So must buses and school buses.
When you follow one of these vehicles toward a crossing, be ready to stop behind it.
Buses, streetcars and light rail
City driving brings its own large vehicles.
A bus, streetcar or trolley may stop at a safety zone or a traffic light.
The handbook says you may then pass it at no more than 10 mph.
Safety zones are areas set aside for people waiting to board.
They may be marked with raised buttons or dotted white lines.
Never drive through a safety zone.
Light rail vehicles have the same rights and responsibilities as other vehicles on public roads.
Never turn in front of an approaching light rail vehicle.
Check for one before you turn across the tracks, and keep a safe distance.
Wind, weather and big vehicles
Tall trucks, buses and trailers catch the wind like a sail.
On a gusty day, a high-sided truck can drift out of its lane without warning.
Give large vehicles extra room when it is windy, and avoid passing them in strong gusts.
Our guide to driving in high winds explains what to watch for.
Rain adds spray, which can blind you for a few seconds as you pass.
Use your wipers early and pass only when you have a long, clear view ahead.
A quick checklist for driving near trucks
- If you cannot see the truck's mirrors, assume the driver cannot see you.
- Never cut in front of a truck and then slow down.
- Stay out of the open space on the right of a turning truck.
- Pass on the left, steadily, and do not linger beside the trailer.
- Keep a long following distance so you can see past the truck.
- Expect trucks, buses and placarded vehicles to stop at railroad crossings.
- Give tall vehicles extra room in strong wind.
The bottom line
Trucks and buses are not more careless than cars. They simply need more room.
Stay visible, give them space to stop and turn, and pass with purpose.
Those habits keep both you and the professional driver beside you out of trouble.
Sources and Further Reading
- California DMV: California Driver Handbook, Section 7, Laws and Rules of the Road (Continued) — supports the No Zones and mirror test, the 300 and 400 foot stopping distances, wide turns, the passing advice, the lane rules for trucks and towing, placarded loads, buses, safety zones and light rail.
- California DMV: California Driver Handbook, Section 8, Safe Driving — supports the general following distance and high wind guidance.