Marked lanes — District of Columbia Permit Test

Marked lanes on the District of Columbia permit test — 4 rules, each with the reason behind it and a question on it while it is fresh.

The rules

On roads with marked lanes you should stay in one lane, and you must not drive partly in one lane and partly in another.

A car straddling two lanes blocks both and gives drivers on either side no clear space beside you.

You must not drive partly in one lane and partly in another
DC Driver Manual, p.72

You should signal your intention to change lanes no less than 300 feet before you do so.

Drivers ahead and behind need time to see where you are going before your car is suddenly in their lane.

You should signal your intention to change lanes no less than 300 feet before you do so.
DC Driver Manual, p.72

When you are driving more slowly than the traffic flow on a highway with two or more lanes in your direction, you should move to and stay in the right lane.

A slow car in the left lane makes faster drivers weave around it, which is when sideswipes happen.

When you are driving more slowly than the traffic flow on a highway that has two or more lanes in your direction, you should move to and stay in the right lane
DC Driver Manual, p.72

If you see a vehicle stopped on the shoulder, you should slow down and move to the left part of your lane or the next lane, if available.

People beside a stopped car may step or open a door into traffic, and a little extra room keeps them from being hit.

If you see a vehicle stopped on the shoulder, you should slow down and move to the left part of your lane or the next lane, if available
DC Driver Manual, p.72

On the test

On a road with marked lanes, what must you not do?

Drive partly in two lanes at once. A car straddling two lanes blocks both and gives drivers on either side no clear space beside you. DC Driver Manual, p.72: “You must not drive partly in one lane and partly in another”

How this works

Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.

You read one law and the reason behind it, then answer a question on that law while it is still fresh. Get it right and you move on; get it wrong and you have found the gap while it is cheap to fix, not on the morning of the exam.

Learning one rule at a time, and proving it immediately, is what turns a manual you skimmed into something you actually know — and it makes studying feel like getting somewhere rather than like waiting to find out.

What it costs

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All District of Columbia permit topics

Where these come from

Every rule here is checked against DC Driver Manual, published by the District of Columbia Department of Motor Vehicles, and against the state code itself. Last checked 2026-10-05.