Turning, Merging, and Passing: Where DMV Test-Takers Slip Up

Most people walk into the California written test feeling fine about traffic signs and shaky about the rules that decide who moves first. Turns, merging, and passing sit right at that intersection. The rules themselves aren't complicated, but the test phrases them in ways that punish half-remembered versions. Below are the mistakes I see most often, what the actual rule is, and how the question usually sounds.

The umbrella rule

Three ideas cover almost everything in this section: signal about 100 feet before you turn, turn from the lane closest to the direction you're headed, and never pass where you can't see far enough ahead. If you're stuck between two answer choices, hold them up against those three ideas and one usually falls away.

Turning positions: wrong lane, wrong answer

This is the single most common slip. People remember "turn from the correct lane" but forget that the right lane depends on direction.

Right turns: start from the lane nearest the right curb or edge of the road, and finish in the first available lane.
Left turns: start from the lane nearest the center line, or from the leftmost lane on a one-way street.
Two-way street to two-way street: begin your left turn just to the left of the center line, then finish in the lane just to the right of the center line.
One-way to one-way: you may turn left from the far-left lane and finish in the far-left lane.

The mistake: answering with where the turn ends when the question asked where it begins, or vice versa. Read for the word "start" or "finish."

Test phrasing it this way: "You are turning left from a two-way street onto another two-way street. Before the turn, you should be positioned closest to…" The answer is just left of the center line.

Scenario: You're stopped at a green light on a two-way street with two lanes headed your way, and a car ahead of you is waiting to turn left. You may not swing out and pass on the right unless the way is clear and it's safe. Passing on the right is for specific situations, not for impatience at an intersection.

Turns on red: the rule people love and misapply

Right on red is familiar. Left on red is where the errors live.

You may turn left on a red light only when you are turning from a one-way street onto another one-way street, with no sign saying otherwise. In every other case, a red light means stop and stay.

The mistake: assuming any red light permits a right turn. It doesn't. If a sign prohibits it, the sign wins. The same goes for treating a red arrow like a plain red light.

Test phrasing it this way: "You are on a one-way street approaching a red light and want to turn left onto another one-way street. You may…" The answer permits the turn after yielding to traffic that has a green light.

Scenario: You're first in line at a red light on a one-way downtown street. The cross street is also one-way, no signs forbid the turn, and pedestrians are clear. You yield to cross traffic, then turn left. If any of those conditions were different, you'd wait.

U-turns: legal unless it's one of the bad spots

A U-turn is generally allowed when you're not creating a hazard, but the test wants the exceptions. Expect to see these:

In a business district, only where posted signs allow it.
Never on a divided highway where a raised divider or barrier separates the directions.
Never where a sign prohibits it, or at a railroad crossing.
Not where you can't see clearly in all directions, or where you'd be turning into oncoming traffic from a hill or curve.

The mistake: assuming no sign means no restriction. Look for the phrase "except where posted" in the answer choices.

Test phrasing it this way: "When may you make a U-turn in a business district?" The answer is: only at an intersection with a green light or green arrow, or where a sign permits it.

Freeway entry and exit: speed and space

Entry is about matching speed; exit is about not leaving it too late.

When merging onto a freeway: be in the proper lane on the on-ramp, build up to near highway speed, signal, check your mirrors, glance over your shoulder, and merge into a gap large enough for your car. Don't stop on the ramp unless you truly must.

When exiting: signal well before the exit, move into the exit lane as soon as it appears, and adjust speed after you're in the exit lane, not while still blocking freeway traffic.

The mistakes: believing you should slow way down before merging (wrong — you merge at traffic speed), or that a freeway exit lane can be entered at the last second.

Test phrasing it this way: "What should you do when entering a freeway from an on-ramp?" The right answer involves being at or near the speed of traffic and merging when it's safe.

Passing restrictions: the curve and hill trap

Passing rules break down into when you may and when you absolutely may not.

You may not pass:

When you're approaching a hill or curve and can't see whether traffic is coming.
Within 100 feet of an intersection, bridge, tunnel, or railroad crossing.
At a crosswalk, or anywhere your view is blocked.
On the left of a driver who is signaling a left turn.
By leaving the paved or main-traveled road.

The mistake: confusing the passing question with a lane-change question. The test often includes a distractor about checking your blind spots, which is correct advice but not what the question asks.

Test phrasing it this way: "You are approaching a curve where you cannot see oncoming traffic. You may pass…" The correct answer is never in that spot; you wait for a straight stretch with clear sight lines.

Quick self-check

1. You're turning right at an intersection onto a two-lane road. Where do you start the turn? A. From the left lane, so you have room B. From the lane closest to the right curb C. From whichever lane has fewer cars

2. On a one-way street at a red light, may you turn left onto another one-way street? A. Yes, if no sign prohibits it and you yield B. No, never on red C. Only if the light is flashing

3. You want to pass on a two-lane road and the car ahead is signaling a left turn. What do you do? A. Wait until it completes the turn, then pass on the left B. Pass on the right if the shoulder is clear C. Pass on the left anyway

Answers: 1-B, 2-A, 3-A.

Key takeaways

Signal about 100 feet before a turn and take it from the lane closest to the direction you're heading.
Left on red is legal only from a one-way street onto another one-way street.
Merge onto a freeway at or near traffic speed; get into your exit lane early.
Never pass on a curve or hill where you can't see oncoming traffic, and don't cross the center line to pass a car that's turning left.
When two answers look right, pick the one that matches a plain rule rather than a special case.

If you want a friendly way to drill these before test day, you can practise with Mia at lastdmv.com.

Frequently asked questions

Can you turn left on a red light in California?

Only when you are turning from a one-way street onto another one-way street, and only if no sign prohibits it. You still have to yield to pedestrians and traffic that has the green light.

How far ahead should you signal before turning?

About 100 feet before the turn, or roughly a city block's short stretch, so people behind you have time to react.

When are you not allowed to pass another vehicle?

Never pass on a curve or hill where you cannot see oncoming traffic, within 100 feet of an intersection, bridge, tunnel, or railroad crossing, at a crosswalk, or by driving off the paved part of the road.

Should you slow down before merging onto a freeway?

No. You should build up to or near the speed of traffic on the ramp and merge into a gap big enough for your vehicle, then adjust from there.