C-31 Construction Zone Traffic Control Contractor license in California

Updated November 1, 2026 · Official name from CSLB's classification list

• 482licenses hold C-31
• 97.8%Clear (CA addresses)
• 17.5%workers' comp exempt (all: 49.6%)
• 100%contractor's bond on file
• 10.5 yrsmedian time licensed
• 90.2%businesses, not sole owners

C-31 contractors set up and take down lane closures, flagging and traffic diversions on streets, highways and other public roads. They use portable gear: cones, delineators, barricades, sign stands, flashing beacons, arrow boards and changeable message signs.

This license almost always works for road crews, utilities and public agencies, not homeowners. You might see one only if a driveway or utility job blocks a public street for a day.

Typical work under C-31

• Lane closures for road and utility work
• Flagging operations
• Detours and traffic diversions
• Arrow boards and changeable message signs
• Cones, barricades and delineators

Work that needs a different license

• Permanent street striping: C-32 Parking and Highway Improvement
• Repaving the road: C-12 Earthwork and Paving or A General Engineering
• Guard rails along the roadway: C-32 Parking and Highway Improvement

Tips before hiring

• If your project needs a street closure, ask your main contractor which traffic control firm it will use and look up that license.
• Ask who obtains the encroachment permit from the city.
• Get the closure hours in writing if neighbors need access.
• If the road is a state highway, ask whether Caltrans has its own approval step.

Where C-31 contractors are

The cities with the most C-31 license holders in CSLB's current file:

1. Traffic Control Contractors in Sacramento: 20
2. San Francisco: 19
3. Fresno: 15
4. Corona: 12
5. Bakersfield: 8
6. San Diego: 7
7. Chino: 6
8. Emeryville: 6
9. Hayward: 6
10. Long Beach: 6

All traffic control contractors lists

Cities with at least 20 C-31 license holders, largest first:

• Sacramento (20)

How to verify a C-31 license

1. Search the business or license number here and confirm C-31 is listed on the profile.
2. Check the same number on CSLB's Instant License Check.
3. Read our full guide to checking a contractor license.

Related license types

• C-32 Parking and Highway Improvement Contractor
• A General Engineering Contractor
• C-12 Earthwork and Paving Contractors

Source: CSLB public data · Updated November 1, 2026 Status can change at any time. Verify on CSLB's Instant License Check.

More license types: ← C-29 Masonry Contractor · C-32 Parking and Highway Improvement Contractor →