Lanes, One-Way Streets & Box Junctions

Staying in the right lane is only half the job — one-way streets, bus and cycle lanes, and yellow box junctions each come with their own rule about when you're actually allowed to use them.

Provisional licenceUK-wide

⏱️ About 12 min

A yellow box junction has a reputation for catching out drivers who've been driving for years, not just learners — because the rule isn't "never enter it," it's a specific condition about your exit. Get that one rule wrong and you can be fined even when you were only following the traffic ahead of you.

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The big idea: Lane discipline means staying in your lane and only changing when it's safe; one-way streets and bus/cycle lanes each carry their own signs and, often, restricted hours; and a box junction's single rule is: don't enter unless your exit is clear — except when you're turning right and only oncoming traffic is blocking you.

🎯 By the end, you'll be able to

Explain the general rule for lane discipline and changing lanes
Read a one-way street sign and understand what it permits
Identify bus and cycle lanes and know that their restrictions can be time-limited
State the box-junction rule precisely, including the right-turn exception

📎 Helpful to know first

Roundabouts & Mini-Roundabouts

Lane discipline: pick a lane, commit, then plan the change

On a multi-lane road, choose the lane suited to your speed and destination and stay in it rather than weaving between lanes to gain small advantages. When you do need to change lanes — to overtake, to position for a turn, or because a lane is ending — use mirrors, signal, and check your blind spot before moving, and only move when there's a safe gap. Lane markings (a broken white line between lanes, a solid white line you shouldn't cross except to pass a stationary obstruction) tell you where you can and can't cross.

Where a solid line runs alongside a broken one, you may cross to overtake only when the broken line is on your side; a solid line on your side means don't cross it.

One-way streets

A one-way street carries traffic in a single direction only, marked by a rectangular ONE WAY sign and often by arrows painted on the road. Once you're on one, position yourself in whichever lane suits your exit — you can normally use any lane on a one-way street, unlike a two-way road where you keep left — but check for lane restrictions (a bus lane, for instance) that might still apply.

ONE WAY marks a street where all traffic moves in a single direction — arrows painted on the road usually confirm it too.

Bus and cycle lanes — and their hours

Bus lanes and cycle lanes are marked by a lane line and, usually, words painted on the surface (BUS, or a cycle symbol), plus a sign at the start giving the exact restriction. Critically, many bus and cycle lanes only operate during specific hours shown on the sign — outside those hours, other traffic may be allowed to use the lane. Always read the times on the sign itself rather than assuming; entering a bus lane during its restricted hours (without being a permitted vehicle) is a traffic offence enforced by camera in many areas.

A bus lane marked BUS on the surface — check the sign at the start of the lane for exactly which vehicles may use it and during which hours.

This sign marks a segregated cycle track that cyclists must use instead of the main carriageway — don't drive or park on it.

Box junctions: the rule is about your exit, not your entry

A box junction is the yellow criss-cross hatching painted over an intersection that tends to gridlock. The rule is precise: you must not enter the box unless your exit road or lane is clear, so you won't end up stopped in the middle of it and blocking cross traffic. Vehicles ahead of you moving slowly, or a queue you can't be sure will clear, both mean you should wait outside the box, whatever the light or traffic ahead is doing.

Yellow criss-cross hatching marks a box junction. Don't enter unless the road or lane you're exiting into is clear, so you never get stuck stationary inside it.

🔑 The one exception: turning right, blocked only by oncoming traffic

There's a single exception to the box-junction rule: if you want to turn right across the box and you're prevented from doing so only by oncoming traffic (not by anything blocking your actual exit road), you may enter the box and wait until it's clear to complete the turn. This exists because a right-turning vehicle would otherwise hold up everyone behind it while waiting outside the box for a gap in oncoming traffic. It does not excuse entering the box when your exit lane itself is blocked or congested.

Check your understanding

1. What does this sign tell you?

ONE WAY marks a street where traffic moves in a single direction only — you can normally choose any lane suited to your exit, subject to other lane restrictions.

2. Why should you check the sign at the start of a bus lane before using it?

Many bus (and cycle) lanes only restrict other traffic during specific hours shown on the sign — outside those hours the lane may be open to general traffic, so always read the times.

3. You want to go straight across a yellow box junction, but the traffic ahead of you in your exit lane is queued and not moving. What should you do?

You must not enter a box junction unless your exit is clear — a queued exit lane means you wait outside the box, whatever the signal is doing.

4. When is it acceptable to enter a box junction even though you can't complete your move immediately?

The one exception is turning right when oncoming traffic — not a blocked exit — is the only thing preventing you from completing the turn.

✅ Key takeaways

Stay in your chosen lane and only change with mirrors, signal, and a safe gap; solid lines mark where you must not cross.
One-way streets carry traffic in a single direction; you can normally use any lane suited to your exit unless another restriction (like a bus lane) applies.
Bus and cycle lanes often only restrict traffic during specific signed hours — always check the sign at the start of the lane.
Never enter a yellow box junction unless your exit is clear — except when turning right and only oncoming traffic is blocking you.

➡️ Lane rules keep traffic moving; the next lesson covers what happens once you stop — where you're allowed to park, wait, or stop at all.

Frequently asked questions

What is the rule for entering a yellow box junction in the UK?

You must not enter a box junction unless the road or lane you want to exit into is clear — the one exception is when you're turning right and only oncoming traffic, not a blocked exit, is preventing you from completing the turn.

Can I drive in a bus lane if it's outside the restricted hours?

Often yes — many bus and cycle lanes only apply to general traffic during specific hours shown on the sign at the start of the lane. Always check the exact times before assuming you may or may not use it.

Can I use any lane on a one-way street?

Generally yes, choosing whichever lane suits the exit you want — but watch for additional restrictions on individual lanes, such as a bus lane or a cycle lane running alongside the general traffic lanes.

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Independent educational content — not affiliated with, endorsed by, or connected to the DVSA, DVLA, or any government body. This is study material, not legal advice; always confirm current rules in the official Highway Code.