Construction Zone Traffic Control (C-31) · Lesson 5 of 6
Portable Changeable Message Signs and Arrow Boards
"Portable Changeable Message Signs and Arrow Boards" is lesson 5 of 6 in the Construction Zone Traffic Control (C-31) Learning Hub. It opens with "What Each Sign Is For" and works through 5 short steps, then a worked example you can check yourself against.
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Steps in this lesson
What Each Sign Is For
Arrow Board Requirements
PCMS Character Size and Capacity
Message and Mounting Rules
Placement and Delineating the Trailer
The worked example in the course applies this lesson to a realistic job in 6 steps, from "Character height" through "The arrow board".
What you'll be able to do
Explain the main idea of "Portable Changeable Message Signs and Arrow Boards" in plain language you can use on the exam.
Apply this step with confidence: "PCMS Character Size and Capacity".
Apply this step with confidence: "Message and Mounting Rules".
Apply this step with confidence: "Placement and Delineating the Trailer".
Test yourself on the worked example and the quick-check quiz inside the classroom.
The diagram for this lesson, exactly as it appears in the Learning Hub.
The first steps of this lesson
Step 1: What Each Sign Is For
A portable changeable message sign (PCMS) tells drivers about an unexpected situation ahead: lane or ramp closures, queues, speed changes, detours (CA MUTCD 2026 Section 6L.05). It may carry only traffic operational, regulatory, warning and guidance messages, never advertising. An arrow board is a matrix sign that gives merging and direction information, and Section 6L.06 says it may only indicate a lane closure, never a lane shift. In arrow or chevron mode it is used only for stationary or moving lane closures on multi-lane roadways; for shoulder work, blocking a shoulder, or closing one lane of a two-lane, two-way road it is used only in the caution mode.
Step 2: Arrow Board Requirements
Section 12-3.30 of the 2025 Caltrans Standard Specifications sets two types. Type I: panel at least 48 x 96 inches, at least 15 panel lights, legible at least 1 mile. Type II: panel at least 36 x 72 inches, at least 13 lights, legible at least 3/4 mile. The lamps are yellow or amber with visors, dim to 50 percent for night use, and the bottom of the sign must be at least 7 feet above the roadway. Standard Plan T10 note 8 calls for the Type I sign on freeway lane closures, one for each lane closed. CA MUTCD 2026 Section 6L.06 says to place it on the shoulder at the beginning of the merging taper (in the closed lane if the shoulder is narrow), behind the channelizing devices that transition traffic.
The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.
Independent exam preparation. Contractors Classroom is not affiliated with the Contractors State License Board, and no course can guarantee a passing result.
