100+ Free C-31 Traffic Control Practice Questions

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2026 Statistics

Key Facts: C-31 Traffic Control Exam

51%

Traffic Control Installation

Official Outline

3.5

Hours Time Limit

CSLB Guidelines

$450

Application Fee

CSLB Fee Schedule

Part 6

CA MUTCD Section

Study Guide

4 Years

Experience Required

CSLB Requirements

This 3.5-hour, computer-delivered exam by PSI requires 4 years of journey-level experience and a $450 application fee. It heavily emphasizes traffic control installation (51%) and planning (18%).

Sample C-31 Traffic Control Practice Questions

Try these sample questions to test your C-31 Traffic Control exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1What is the minimum required merging taper length (L) for closing a 12-foot wide traffic lane on a California highway with a posted speed limit of 55 mph?

A.660 feet, calculated using L = W × S for speeds of 45 mph or greater.

B.302 feet, calculated using L = W × S² / 60 for low-speed urban streets.

C.440 feet, calculated using L = 0.67 × W × S for shifting tapers only.

D.220 feet, calculated using L = 0.33 × W × S for shoulder tapers only.

Explanation: Per CA MUTCD Section 6C.08, for speeds of 45 mph or greater, the merging taper length formula is L = W × S. For a 12-foot lane at 55 mph, L = 12 × 55 = 660 feet. Taper lengths must never be reduced below formula requirements in stationary lane closures.

2A traffic control contractor is designing a merging taper to close a 12-foot lane on an urban street posted at 35 mph. What is the minimum taper length required?

A.420 feet, calculated using L = W × S for high-speed highway merging tapers.

B.245 feet, calculated using L = W × S² / 60 for speeds of 40 mph or less.

C.123 feet, calculated using L = W × S² / 120 for shifting tapers on streets.

D.82 feet, calculated using L = W × S² / 180 for shoulder tapers on streets.

Explanation: Per CA MUTCD Section 6C.08, for speeds of 40 mph or less, the merging taper length formula is L = W × S² / 60. For a 12-foot lane at 35 mph, L = 12 × (35)² / 60 = 12 × 1225 / 60 = 245 feet.

3A contractor must install a shifting taper to align traffic across a 12-foot lateral shift on a highway posted at 60 mph. What is the minimum required shifting taper length?

A.720 feet, which represents the full merging taper length for a 60 mph zone.

B.540 feet, which represents three-quarters of the full merging taper length.

C.360 feet, which equals L / 2 (half of the full merging taper length).

D.240 feet, which equals L / 3 (one-third of the full merging taper length).

Explanation: Per CA MUTCD Section 6C.08, a shifting taper is used when traffic is shifted laterally without reducing the number of lanes. The length of a shifting taper is L / 2. For L = 12 × 60 = 720 feet, the shifting taper length is 720 / 2 = 360 feet.

4What is the minimum required shoulder taper length when closing a 10-foot wide paved shoulder on a roadway with a posted speed of 50 mph?

A.500 feet, which is the full merging taper length required for closing lanes.

B.333 feet, which is two-thirds of the full merging taper length for shifts.

C.250 feet, which is half of the full merging taper length for shifts.

D.167 feet, which equals L / 3 (one-third of the merging taper length).

Explanation: Per CA MUTCD Section 6C.08, a shoulder taper is used when a paved shoulder is closed on a high-speed roadway. The minimum shoulder taper length is L / 3. For a 10-foot shoulder at 50 mph, L = 10 × 50 = 500 feet, so the shoulder taper is 500 / 3 = 166.7 feet, rounded up to 167 feet.

5What is the standard taper length range specified in CA MUTCD for one-lane, two-way traffic control using flaggers or temporary signals?

A.50 feet to 100 feet maximum, using 5 to 6 channelizing devices.

B.150 feet to 300 feet maximum, using 10 to 12 channelizing devices.

C.300 feet to 500 feet maximum, using 15 to 20 channelizing devices.

D.500 feet to 1000 feet maximum, using 25 to 30 channelizing devices.

Explanation: Per CA MUTCD Section 6C.08 and Caltrans Standard Plan T10, the taper length for a one-lane, two-way traffic control setup should be short—typically 50 feet to 100 feet maximum—with 5 to 6 channelizing devices. Because traffic is controlled by flaggers or temporary signals, drivers must stop or proceed slowly through the work zone, so long merging tapers are unnecessary. Excessively long tapers in this context can actually confuse drivers who are expecting to stop at a flagger station rather than merge at highway speed.

6According to CA MUTCD Table 6C-2, what is the minimum required longitudinal buffer space length for a work zone with a posted speed limit of 45 mph?

A.250 feet, based on urban low-speed stopping sight distance metrics.

B.360 feet, based on standard stopping sight distance for 45 mph.

C.495 feet, based on rural high-speed stopping sight distance metrics.

D.645 feet, based on freeway express stopping sight distance metrics.

Explanation: Per CA MUTCD Table 6C-2 (Stopping Sight Distance as a Function of Speed), the recommended longitudinal buffer space for a posted speed of 45 mph is 360 feet. Buffer spaces must remain free of equipment, workers, and stored materials.

7According to CA MUTCD Table 6C-2, what is the minimum required longitudinal buffer space length for a freeway work zone posted at 65 mph?

A.425 feet, which corresponds to the stopping distance at 50 mph.

B.570 feet, which corresponds to the stopping distance at 60 mph.

C.645 feet, which corresponds to the stopping distance at 65 mph.

D.730 feet, which corresponds to the stopping distance at 70 mph.

Explanation: Per CA MUTCD Table 6C-2, the longitudinal buffer space for 65 mph is 645 feet. The longitudinal buffer space provides an recovery area for errant drivers and must never be used for parking vehicles or storing materials.

8A traffic estimator is calculating the number of channelizing devices required for a 660-foot merging taper on a 55 mph highway. What is the minimum device count?

A.7 devices, spaced at double the speed limit (110 feet apart).

B.9 devices, spaced at 75-foot intervals along the merging taper.

C.11 devices, spaced at 60-foot intervals along the merging taper.

D.13 devices, spaced at the speed limit in feet (55 feet apart).

Explanation: Per CA MUTCD Section 6F.63, the maximum spacing for channelizing devices in a taper is equal to the posted speed limit in feet (S feet). For 55 mph, spacing is 55 feet. Number of devices = (Taper Length / Spacing) + 1 = (660 / 55) + 1 = 12 + 1 = 13 devices.

9How many cones are required for a 1,000-foot tangent section of a freeway lane closure with a posted speed limit of 60 mph?

A.9 cones, placed at a maximum tangent spacing of 2 × S (120 feet).

B.14 cones, placed at a maximum tangent spacing of 1.25 × S (75 feet).

C.18 cones, placed at a maximum tangent spacing of 1.0 × S (60 feet).

D.26 cones, placed at a maximum tangent spacing of 0.67 × S (40 feet).

Explanation: Per CA MUTCD Section 6F.63, maximum spacing for channelizing devices in a tangent section is 2 × S feet (where S is speed in mph). For 60 mph, tangent spacing is 2 × 60 = 120 feet. Device count = (1000 / 120) + 1 = 8.33 + 1 = 9 cones.

10When reading Caltrans Standard Plan T9, what does a dashed line of channelizing devices positioned diagonally across a lane represent?

A.A permanent shoulder widening project boundary line.

B.A merging taper for closing an active traffic lane.

C.A buffer zone boundary reserved for emergency vehicles.

D.A pedestrian detour channelization path across work areas.

Explanation: On Caltrans Standard Plans (T9 through T17), diagonal lines of channelizing devices across traffic lanes represent merging or shifting tapers designed to transition live traffic out of closed lanes into open lanes. Recognizing these symbols is essential for field crews who must interpret plans accurately during installation. A merging taper diagonal closes a lane entirely, while a shifting taper diagonal moves traffic laterally without reducing the number of through lanes.

About the C-31 Traffic Control Exam

The C-31 Construction Zone Traffic Control exam evaluates the applicant's knowledge of CA MUTCD Part 6, planning, installing, and maintaining temporary traffic control devices safely.

Assessment

Question count not published by the exam provider

Time Limit

3.5 hours

Passing Score

Disclosed at test site

Exam Fee

$450 application fee (California Contractors State License Board (CSLB))

C-31 Traffic Control Exam Content Outline

18%

Planning and Estimating

Evaluating project sites, determining required traffic control plans, and estimating labor and equipment costs.

11%

Notifications and Coordination

Coordinating with local agencies, obtaining permits, and notifying emergency services.

51%

Traffic Control Installation

Implementing, maintaining, and removing temporary traffic control devices according to CA MUTCD standards.

Transportation and Training

Safe loading, transport of devices, and training flaggers and field personnel.

12%

Safety

Cal/OSHA safety regulations, PPE, hazardous materials, and safe work practices.

How to Pass the C-31 Traffic Control Exam

What You Need to Know

Passing score: Disclosed at test site
Assessment: Question count not published by the exam provider
Time limit: 3.5 hours
Exam fee: $450 application fee

Keys to Passing

Work through all 100 available questions
Review every answer and explanation
Track weak areas and revisit them
Use our AI tutor for tough concepts

C-31 Traffic Control Study Tips from Top Performers

1Master CA MUTCD Part 6, particularly the tables for taper lengths, device spacing, and buffer zones.

2Understand the formulas for calculating merging taper (L = W x S or L = W x S^2 / 60).

3Review Cal/OSHA requirements for flagger training and required high-visibility apparel.

4Practice estimating the number of channelizing devices needed based on taper length and spacing rules.

5Study the proper sequence for installing and removing temporary traffic control zones.

Frequently Asked Questions

What does the C-31 exam focus on?

It heavily emphasizes CA MUTCD Part 6 standards, especially the installation, maintenance, and removal of temporary traffic control systems.

How long is the exam?

The exam is 3.5 hours (210 minutes) and is administered on a computer at PSI testing centers.

What are the experience requirements?

You need 4 years of qualifying journey-level experience in traffic control within the preceding 10 years.

Are reference materials allowed during the exam?

No. The C-31 exam is closed-book. You cannot bring the CA MUTCD or any other materials into the testing room.

100+ Free C-31 Traffic Control Practice Questions

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