Traffic control on roadside line clearance work: what section 3421(j) hands a tree crew
Title 8 section 3421(j) requires traffic control conforming to Construction Safety Orders sections 1598 and 1599 wherever vehicular or pedestrian traffic may endanger a tree crew. Section 1598 requires controls conforming to the California MUTCD and high-visibility garments. Section 1599 requires flaggers trained in nine listed subjects, documented under section 3203.
A 55-foot bucket truck sets up on a two-lane rural road to reach a limb over a 12 kV primary. The outriggers take three feet of the westbound lane. Nothing in Article 38 of the High-Voltage Electrical Safety Orders tells the crew what to do about the three feet. Section 2951 runs to nine subsections and never uses the word traffic. Neither does section 2950.
The sentence that governs those three feet is one line in a different set of orders entirely, and it has been operative since October 25, 2012.
The sentence that hands a tree crew the Construction Safety Orders
Section 3421(j) of the General Industry Safety Orders:
Where vehicular or pedestrian traffic may endanger employees, traffic control shall be provided that conforms to the requirements of Sections 1598 and 1599 of the Construction Safety Orders.
One sentence, and it does the whole job of pointing. The trigger is "may endanger," not "encroaches on," and not "closes a lane." A chipper on the shoulder with a groundman walking behind it meets the trigger.
Section 3421 sits in Article 12, Tree Work, Maintenance or Removal. Section 3420(a) gives the article's scope as tree and ornamental palm maintenance and removal. Its second note refers line clearance work to Article 38. That note points the reader onward, and Article 12 still applies to the crew. What Article 12 owns and who it reaches is the sibling question, and the short answer is that a line clearance crew carries Article 12 and Article 38 at the same time.
So the governing text lives in the Construction Safety Orders, in Article 11, Vehicles, Traffic Control, Flaggers, Barricades, and Warning Signs. A utility line clearance crew is doing maintenance work. It gets the construction rule anyway, because section 3421(j) hands it over by name.
Section 1598, and the manual it still names
Where a hazard exists to employees because of traffic or haulage conditions at work sites that encroach upon public streets or highways, a system of traffic controls in conformance with the "California Manual on Uniform Traffic Control Devices for Streets and Highways, January 13, 2012," which is herein incorporated by reference and referred to as the "Manual", published by the State Department of Transportation, shall be required so as to abate the hazard.
That is section 1598(a) entire. The substantive content is in the manual, and the date on the manual is the problem.
The history note tells you when that date was set. Amendment of subsection (a), and amendment of the manual incorporated by reference, filed May 29, 2014, operative July 1, 2014. Cal/OSHA has not touched the reference since. Caltrans has replaced the manual twice.
Edition | Status |
CA MUTCD, January 13, 2012 | The edition incorporated by reference into sections 1598 and 1599 |
CA MUTCD 2014, Revision 9, April 1, 2025 | The last revision of the edition that replaced it |
CA MUTCD 2026, effective January 18, 2026 | Caltrans' adoption of FHWA's MUTCD 11th Edition of December 19, 2023 |
Which one does a crew build to? Build to the current one. Two reasons, and neither is a preference.
Section 1598(b) incorporates Vehicle Code section 21400 by reference for the size and design of signs, lights and devices. Subdivision (c) of that statute is the operative line: "only those signs, lights, and devices as are provided for in this section shall be placed upon a highway to warn traffic of work that is being performed on the highway."
It tracks whatever Caltrans has currently adopted. It governs the road whichever edition a safety order happens to name. Federally, 23 CFR 655.603(a) makes the approved MUTCD the national standard for every street and highway open to public travel.
The renumbering is the practical bite. Flagger control was Chapter 6E in the CA MUTCD 2014 edition and is Chapter 6D in the 2026 edition. Typical applications moved from Chapter 6H to Chapter 6P. Any job hazard analysis, traffic control plan or training deck that cites a CA MUTCD chapter by letter needs to be reread against the 2026 edition rather than assumed forward.
The garment, and the class the safety order never prints
Section 1598 covers three things about clothing and leaves out the one number a purchasing agent needs.
Employees (on foot) exposed to the hazard of vehicular traffic shall wear warning garments such as vests, jackets, or shirts manufactured in accordance with the requirements of the American National Standards Institute (ANSI)/International Safety Equipment Association (ISEA) 107-2004, High Visibility Safety Apparel and Headwear.
That is 1598(c). Subsection (d) adds that during hours of darkness the garments shall be retroreflective, with the retroreflective material visible at a minimum of 1,000 feet. Subsection (e) puts the class selection on the employer, "by consulting the Manual, apparel manufacturer, ANSI/ISEA 107-2004, Appendix B or the American Traffic Safety Services Association (ATSSA)."
Consult the Manual, then, because the Manual answers it. CA MUTCD 2026 section 6C.05:
For daytime and nighttime activity, all workers, including emergency responders, within the right-of-way who are within the TTC zone shall wear high-visibility safety apparel that meets the Performance Class 2 or 3 requirements of the ANSI/ISEA 107-2015 publication entitled "American National Standard for High-Visibility Safety Apparel and Headwear," or equivalent revisions.
Class 2 is the floor, the referenced standard is the 2015 revision, and paragraph 07 of the same section adds that flaggers working at night should be in Class 3. Section 6C.05 then cites sections 1598 and 1599 back at the reader, which is as close as the two documents come to shaking hands.
One number to check before the next order goes in. A Class 1 vest, the kind bought for a residential yard crew, fails section 6C.05 the moment that crew parks on a public road.
A second thing to check is the citation in your own manual. Many tree care safety programs cite 23 CFR 634.3 for the high-visibility requirement. That part is gone. FHWA deleted it in the final rule adopting the 2009 MUTCD, published December 16, 2009 and effective January 15, 2010:
As proposed in the NPA, the FHWA revises the Code of Federal Regulations to delete title 23 CFR part 634 regarding Worker Visibility, in order to incorporate the provisions into the MUTCD, which is applicable to all public roads.
The requirement did not lapse. It moved into the Manual, where section 6C.05 now carries it. Title 23 of the CFR today runs 633, then 635.
The flagger: nine subjects, a qualified trainer, and a file
Section 1599(a) sets the trigger:
A flagger or flaggers shall be utilized at locations on a construction site where barricades and warning signs cannot control the moving traffic.
Section 1599(g) sets the training, and it does it as a closed list. The training and instructions shall be based on the Manual and work site conditions and also include:
1. flagger equipment which must be used 2. layout of the work zone and flagging station 3. methods to signal traffic to stop, proceed or slow down 4. methods of one-way traffic control 5. trainee demonstration of proper flagging methodology and operations 6. emergency vehicles traveling through the work zone 7. handling emergency situations 8. methods of dealing with hostile drivers 9. flagging procedures when a single flagger is used (when applicable)
Item 5 is the one that has to physically happen. A slide deck and a signature do not produce a trainee demonstration of proper flagging methodology. Somebody hands the recruit a paddle and watches them work it.
Section 1599(h) adds that flaggers "shall be trained by persons with the qualifications and experience necessary to effectively instruct the employee in the proper fundamentals of flagging moving traffic." California names no course, no card and no issuing body for either the flagger or the trainer. The employer decides who is qualified to instruct, and defends that decision if asked.
The record is section 3203(b)(2): employee name or other identifier, training dates, types of training, and training providers, kept for at least one year. That is the same file the rest of the crew's qualification documentation lives in, and it is short enough that there is no excuse for it being missing.
CA MUTCD 2026 section 6D.01 reprints the same nine items, then points the reader back at section 1599 for flagger training and section 3203 for the documentation. The two books agree, which is rare enough to be worth knowing when an evaluator asks which one you follow.
What the flagger is allowed to hold
Section 6D.05 of the 2026 manual closes the list to three devices:
Flaggers shall use a STOP/SLOW paddle, a flag (for emergency situations only), or an Automated Flagger Assistance Device (AFAD) (see Sections 6L.02 through 6L.04) to control road users approaching a TTC zone. The use of hand movements alone without a paddle, flag, or AFAD to control road users shall be prohibited when controlling traffic in a one-lane two-way operation.
The paddle specification is in section 6D.02 and Figure 6D-1.
Device | What the manual requires |
STOP/SLOW paddle | Octagonal, on a rigid handle, 18 inches minimum per Figure 6D-1; retroreflectorized when used at night |
STOP/SLOW paddle, 24 by 24 inch | May be used where greater emphasis is needed and speeds are 30 mph or more |
Paddle on a staff | Bottom of the sign should be a minimum of 6 feet above the pavement |
Flag | Emergency situations only; red or fluorescent orange-red, minimum 24 inches square, staff approximately 36 inches |
The red rag kept behind the seat of the chip truck is not on that list. Neither is a hand. On a two-lane road where the bucket has taken a lane, a groundman waving cars through is outside section 6D.05 whatever else the crew has set out.
Where the flagger stands, and the second person California has already spent
Section 6D.05 tells the flagger where to be:
The flagger should be stationed sufficiently in advance of the workers to warn them (for example, with audible warning devices such as horns or whistles) of approaching danger by out-of-control vehicles. The flagger should stand alone, away from other workers, work vehicles, or equipment.
Section 6D.06 adds that flagger stations shall be preceded by an advance warning sign or signs, shall be illuminated when flagging is used at night, and that the flagger should identify an escape route.
Now read that against section 2951(d), which California already spends on the same crew:
During all tree trimming operations performed in accordance with the requirements of subsection (b) above, there shall be another qualified line clearance tree trimmer or trainee within normal (that is, unassisted) voice communication at each work location to render immediate assistance.
Standing alone and in advance of the workers, and standing within unassisted voice communication ready to render immediate assistance, are two different places on the road. What immediate assistance has to mean is the reason the second person exists, and a person facing oncoming traffic with a paddle is not positioned to provide it.
Count the two-lane job honestly. CA MUTCD section 6E.02 says traffic should be controlled by a flagger at each end of a constricted section, with one designated as coordinator. A single flagger is allowed only where the zone is short enough for that flagger to see one end from the other.
The flag transfer method, where a driver carries a token through the zone, carries a one-line California amendment in section 6E.03: "This section is deleted for application and shall not be used in California." So the minimum roadside crew is the trimmer aloft, the second qualified trimmer on the ground, and one or two flaggers who are doing nothing else.
Section 2951 does not resolve this and neither does section 1599. The employer decides the assignment, and the right place to record it is the tail gate briefing section 2951(a) already requires before the operation commences. The Division decides afterward whether anybody on that job site was actually free to render immediate assistance.
The flagger's own approach distance
The person holding the paddle is usually the newest person on the crew. That matters electrically, because the credential is what sets the distance.
A flagger without the credential is an other person under Table 1 of section 2950, and Table 1 gives that class its own distance. Federally, OSHA puts the same worker outside 1910.269 altogether: "Unqualified employees must maintain the minimum approach distances of at least 10 feet from overhead power lines," and section 1910.269 does not apply to tree trimming performed by unqualified employees. Which credential permits what is the sibling page, and the flagger sits on the wrong side of it.
Three consequences on a real job site follow from that.
The flagger station cannot be sited under the part of the span being worked, however good the sight distance is there.
The flagger cannot be pulled off the paddle to tail a rope on a limb near the conductor, because the task is closed to them.
Section 6D.05's instruction to stand away from work vehicles happens to be the electrically correct answer too. A groundman touching the truck while the boom is near the conductor is exposed to step and touch potential, and the flagger's assigned position already keeps them off it.
Fifteen feet, ten feet, and one hour
Three numbers decide how much hardware comes off the truck. All three are in the 2026 manual.
Fifteen feet. Section 6N.05 states that temporary traffic control "generally is not needed where work is confined to an area 15 feet or more from the edge of the traveled way." The same paragraph takes it back where equipment travels on or crosses the roadway, which describes almost every removal that feeds a chipper parked at the curb. Section 6B.04 carries the matching allowance for advance warning signs at the same 15 feet, or more than 2 feet behind the curb.
Ten feet. Section 6N.07: "Unless the lane encroachment permits a remaining lane width of 10 feet, the lane should be closed." Measure from the outrigger pad, not from the tire.
One hour. Section 6N.01 defines five categories of work duration, and the tree crew's day usually lands in two of them.
Category | Time at a location |
Long-term stationary | More than 3 days |
Intermediate-term stationary | More than one daylight period up to 3 days, or nighttime work lasting more than 1 hour |
Short-term stationary | Daytime work occupying a location more than 1 hour within a single daylight period |
Short duration | Up to 1 hour |
Mobile | Work that moves intermittently or continuously |
Section 6N.01 then says plainly that "most maintenance and utility operations are short-term stationary work," and closes the obvious loophole: "Safety in short-duration or mobile operations should not be compromised by using fewer devices simply because the operation will frequently change its location." A crew clearing six spans before lunch is a mobile operation, and the sign package moves with it.
Table 6B-1 sets the spacing of those signs.
Road type | Recommended minimum spacing between signs |
Urban, 25 mph or less | 100 feet |
Urban, 50 mph or more | 350 feet |
Rural | 500 feet |
Expressway or freeway | 1,000 feet, then 1,500 feet, then 2,640 feet |
The federal standards for this work have no traffic rule
There is no traffic control paragraph in 29 CFR 1910.269. The word traffic appears once in the whole standard, in the enclosed space attendant requirement at paragraph (e)(6). Paragraph (r), which is the line clearance paragraph and the one that sorts the three qualification tiers, says nothing about the road.
What fills the gap depends on how the work is classified.
Where the work is construction, 29 CFR 1926.200(g)(2) requires that the design and use of all traffic control devices for protection of construction workers conform to Part 6 of the MUTCD, and 1926.201(a) does the same for flaggers and their warning garments. OSHA's incorporation is frozen too. Section 1926.6 names the 2009 Edition of the MUTCD with Revisions 1 and 2 of May 2012.
Everywhere else, the hook is the General Duty Clause. OSHA's letter of interpretation of August 5, 2009 is explicit about why:
OSHA standards require such employees to wear high visibility garments in two specific circumstances: when they work as flaggers and when they are exposed to public vehicular traffic in the vicinity of excavations. However, other construction workers in highway/road construction work zones are also exposed to the danger of being struck by the vehicles operating near them. for such workers, section 5(a)(1) of the OSH Act, 29 U.S.C. §654(a)(1), also known as the General Duty Clause, requires similar protection.
Read the footnotes on that letter before you lean on it. Its supporting citation is 23 CFR 634.3, which FHWA removed four months after the letter issued. The recognized-hazard reasoning survives the removal; the citation does not.
The consensus standard is more direct than either. ANSI Z133-2026 section 3.5 requires that "traffic and pedestrian control around the work site shall be established prior to the start of all arboricultural operations." It requires workers with specific temporary traffic control zone responsibilities to be trained in techniques, device usage and placement.
It requires workers exposed to moving roadway traffic to wear apparel conforming to ANSI/ISEA 107. Z133 is voluntary, and what that is worth against a California safety order is the sibling question. In California, section 3421(j) makes the point moot by requiring the same thing with an enforceable number attached.
Where it bites
Four places, in the order an inspection tends to find them.
The edition. A traffic control plan citing CA MUTCD Chapter 6E for flagger control is citing the 2014 book. Flagger control is Chapter 6D as of January 18, 2026, and typical applications are Chapter 6P.
The garment class. Section 1598 names ANSI/ISEA 107-2004 and prints no class, so nothing on the face of the safety order stops a crew from buying Class 1. Section 6C.05 of the manual that section 1598(e) tells you to consult sets the floor at Class 2, and at Class 3 for flaggers at night.
The second person. If the same name appears on the tail gate briefing as the section 2951(d) second qualified trimmer and as the flagger, one of those two duties was not being performed. Staff it as two people or write down why the work location did not need both at once.
The file. Section 1599(g) training is documented under section 3203(b)(2) and kept for at least one year: name, dates, type, provider. A prime asking for the traffic control record is asking for four fields, and the absence of them is the easiest finding on this page to produce.
Further reading
Section 2951: the nine subsections that govern a line clearance crew's day: The work practice rule that spends the crew's second person before traffic control asks for one.
Article 12 of the General Industry Safety Orders: The article section 3421(j) sits in, and the scope sentence that reaches a line clearance crew.
Table 1 of 8 CCR 2950: the minimum approach distance, and who owes it: The distance a flagger owes, because a flagger is usually not a qualified line clearance tree trimmer.
Frequently asked questions
What traffic control does a California tree crew have to provide?
Title 8 section 3421(j) requires traffic control conforming to sections 1598 and 1599 of the Construction Safety Orders wherever vehicular or pedestrian traffic may endanger employees. Section 1598 requires a system of traffic controls conforming to the California Manual on Uniform Traffic Control Devices, and warning garments for employees on foot. Section 1599 requires a trained flagger wherever barricades and warning signs cannot control moving traffic.
Does Article 38 say anything about traffic control for line clearance work?
No. Section 2950 and section 2951 are the whole of Article 38, and the word traffic appears in neither of them. Traffic control for a line clearance crew comes from section 3421(j) of the General Industry Safety Orders, which sends the employer to the Construction Safety Orders.
Which edition of the California MUTCD applies?
Sections 1598 and 1599 incorporate by reference the California Manual on Uniform Traffic Control Devices for Streets and Highways dated January 13, 2012. Caltrans has since replaced that manual twice. The current edition is CA MUTCD 2026, effective January 18, 2026. Vehicle Code section 21400(c) permits only the signs, lights and devices provided for under that section to be placed on a highway, which is why crews build to the current manual.
What does a flagger have to be trained on in California?
Section 1599(g) lists nine subjects: flagger equipment, the layout of the work zone and flagging station, methods to signal traffic to stop, proceed or slow down, methods of one-way traffic control, a trainee demonstration, emergency vehicles traveling through the work zone, handling emergency situations, methods of dealing with hostile drivers, and flagging procedures when a single flagger is used. Section 1599(h) requires the trainer to be qualified and experienced. The documentation is kept under section 3203.
Can the second qualified tree trimmer required by section 2951(d) also be the flagger?
Section 2951(d) requires that second person to be within normal unassisted voice communication at each work location to render immediate assistance. CA MUTCD section 6D.05 says the flagger should stand alone, away from other workers, work vehicles or equipment, and should be stationed sufficiently in advance of the workers to warn them. The two positions are not the same position. The employer decides how to staff it, and the Division decides afterward whether anybody was actually free to render immediate assistance.
