One lane road ahead sign: what it means

One lane road ahead sign: an orange diamond with the words ONE LANE ROAD AHEAD in black
Drawing: Drivoku, based on MUTCD sign W20-4. Simplified; real signs follow the FHWA Standard Highway Signs specifications.

The ONE LANE ROAD AHEAD sign warns that traffic in both directions will have to share a single lane ahead. A flagger or a signal usually controls who goes.

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What does the ONE LANE ROAD AHEAD sign mean?

MUTCD Section 6H.06 says this sign is used only before the point where traffic in both directions must use one common lane. MUTCD Part 6 describes the ways this is controlled, such as flaggers, pilot cars or a temporary signal (Section 6E.01).

Quick quiz

What does the sign at the top of this page mean?

  1. Traffic both ways shares one lane ahead.
  2. A flagger is controlling traffic ahead.
  3. The road gets narrower ahead.

Show answer

A. Traffic both ways shares one lane ahead. Traffic in both directions must use one lane ahead (MUTCD Section 6H.06). Source: MUTCD 11th Edition, Part 6, Temporary Traffic Control: Sections 6E.01, 6H.06, FHWA; MUTCD 11th Edition, FHWA

Where will you see it?

Before work on two-lane roads where one lane is closed.

What should you do?

Slow down and be ready to stop. Follow the flagger, the pilot car or the temporary signal, and do not go until you are told to.

What do people get wrong?

Following the car in front through the one-lane section after the flagger has turned the paddle to STOP.

Common questions

Who controls a one-lane work zone?

MUTCD Section 6E.01 describes flaggers, pilot cars, temporary traffic signals and stop or yield control.

What does a flagger’s SLOW paddle mean?

Go ahead slowly with care. STOP means stop (MUTCD Section 6D.05).

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Sources

Checked on 3 November 2026 against the MUTCD 11th Edition (FHWA), Sections 6E.01 and 6H.06.

  1. MUTCD 11th Edition, Part 6, Temporary Traffic Control: Sections 6E.01, 6H.06, FHWA
  2. MUTCD 11th Edition, FHWA. FHWA lists the current version as the 11th Edition with Revision 1, dated December 2025

Sign pictures are our own simplified drawings of the MUTCD designs, which are in the public domain (MUTCD Section 1D.06). Sources and image credits.

This text was written with AI help, checked against the MUTCD and approved by Fri Vei AS. Last updated .

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