R4-8 Keep Left
The R4-8 Keep Left sign is a California MUTCD regulatory sign. It is shown here as an educational reference with the official FHWA Standard Highway Signs layout and California sizing guidance.
- Sign Name
- Keep Left
- General Meaning
- The R4-8 Keep Left sign is a California MUTCD regulatory sign.
- MUTCD Code
- R4-8
- Typical Use
- At the point where the regulation applies, per CA MUTCD Part 2B.
- Sign Category
- Regulatory Signs
Specifications
- Standard Shape
- Rectangle
- Background Color
- White
- Legend / Symbol
- Black legend
- Border
- Black
- Reflectivity
- High Intensity (for nighttime visibility)
- Compliance
- MUTCD / CA MUTCD
Standard Sizes (inches)
- Rectangle RectanglePer CA MUTCD minimum for the roadway type
Material / Application Notes
Used where keep left conditions apply on a California project. Confirm placement and supplemental plaques against the applicable CA MUTCD standard.
View this sign on the Federal MUTCD (FHWA)California Notes
California-specific application notes and adoptions may differ. Review California requirements where applicable.
What It Means / When This Sign Is Used
In the field, R4-8 Keep Left is typically positioned at the advance warning area, ahead of the work. Common deployments include used where keep left conditions apply on a California project; selected and sized per the CA MUTCD and the roadway type; coordinated with the overall traffic control plan and permit. Always confirm its size, retroreflective sheeting, spacing, and placement against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
Learn more about Keep Left sign requirementsWhen & Where It's Used
- Used where keep left conditions apply on a California project
- Selected and sized per the CA MUTCD and the roadway type
- Coordinated with the overall traffic control plan and permit
Placement on a Traffic Control Plan
- Where it sits
- At the point where the regulation applies, per CA MUTCD Part 2B.
- CA MUTCD reference
- CA MUTCD Part 2B (Regulatory Signs)
- Typical minimum size
- Per CA MUTCD minimum for the roadway type
California / Field Use Notes
R4-8 Keep Left is used in California per the CA MUTCD. Confirm its size, retroreflective sheeting, placement, and spacing against the CA MUTCD 2026 and the reviewing agency before finalizing the traffic control plan.
In Los Angeles, temporary regulatory changes (speed, one-way, turn or entry restrictions) generally involve LADOT review, and on state highways Caltrans District 7. Regulatory authority cannot be created by signing alone — confirm the change is authorized by the agency with jurisdiction over the roadway.
Common Plan Review Comments
- Temporary regulatory control not warranted or conflicts with existing control.
- Reduced speed limit posted without proper speed-setting authorization.
- Wrong-way protection (DO NOT ENTER / WRONG WAY) missing at closed approaches.
- Sign size not appropriate for the facility.
Confirm R4-8 Keep Left is the correct designation, size, and placement for the condition. Public Ready can review sign selection against the TCP and agency requirements.
Related Signs
View All R-Series Signs
Educational reference only. This is not an official Caltrans, FHWA, or local agency publication and is not legal or engineering advice. Always verify sign selection, size, placement, spacing, and application against the current CA MUTCD 2026, Caltrans sign specifications, Standard Plans, project documents, and the reviewing agency’s requirements. Local jurisdictions may impose additional requirements, and final selection, placement, and dimensions may require engineering judgment or agency approval. Written against California MUTCD 2026 (effective January 18, 2026) and the Federal MUTCD 11th Edition. Official sources last verified June 2026.
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