Overhead Crane Hand Signals for Safe Slab Moves

In a stone shop, the overhead crane does the heaviest and least forgiving work in the building. It pulls slabs off A-frames, carries them over the saw line, sets them on the bridge saw table and returns finished pieces to the racks. Every one of those moves happens over concrete, often next to running saws and polishers loud enough to drown out a shout. When the person under the hook and the person on the pendant or in the cab cannot hear each other, hand signals are the language that keeps the slab, and the people around it, where they belong.

This guide explains the standard overhead crane hand signals as published in ASME B30.2, how they compare with the construction signals in OSHA’s Subpart CC, who should be giving them, and what changes when the load hanging below the hook is a polished slab on a vacuum lifter or a pair of clamps. It also covers what to do when visual contact breaks down, how radios should be used, and how the rules differ between a general industry fabrication shop and a construction site. Each signal described here was checked against the published text of the standards.

Which Rules Govern Signals in a Slab Shop

A fabrication shop is general industry, and its overhead and gantry cranes fall under 29 CFR 1910.179. That section requires that only designated personnel operate the crane, that cranes with a power traveling mechanism have a gong or other effective warning signal, that the warning be sounded when starting the bridge and when the load or hook approaches near or over personnel, that the operator avoid carrying loads over people, and that the operator not leave the controls while a load is suspended. What 1910.179 does not do is lay out a hand-signal chart or a signal person program. For that, shops look to the industry consensus standard, ASME B30.2, which covers overhead and gantry cranes and includes a figure of standard hand signals.

Construction is handled differently. OSHA’s cranes and derricks in construction rule, 29 CFR 1926 Subpart CC, requires a signal person when the point of operation is not in full view of the operator, when the view in the direction of travel is obstructed, or when the operator or the person handling the load decides one is needed for site-specific safety reasons. When hand signals are used, the Standard Method in Appendix A to Subpart CC must be used unless it is infeasible or the operation is not covered, and signal persons must be qualified under 1926.1428. Note the crossover in 1926.1438: an overhead crane permanently installed in a facility and used for construction stays under 1910.179 (except paragraph (b)(1)), while overhead and gantry cranes that are not permanently installed follow listed parts of Subpart CC, 1910.179 and ASME B30.2-2005.

For a countertop company, that usually means two regimes in one business. Inside the shop, the bridge crane over the saw line is a general industry crane and the B30.2 signals are the practical standard. On a jobsite, a boom truck or mobile crane lifting slabs to an upper floor is construction equipment, and the Appendix A signals, signal person qualification and radio rules in Subpart CC apply. Crews who do both should learn both charts and know which one is in play before the first lift.

Reading and Giving the Standard Signals

ASME B30.2 states that signals to the operator shall follow the standard unless voice communication such as telephone or radio is used, that signals should be discernible or audible to the operator, and that hand signals shall be posted conspicuously and should be as illustrated in its figure of standard hand signals. The descriptions in the table below are taken from the 2005 edition of B30.2, which OSHA incorporated by reference. The hoist, lower, travel, move slowly, multiple trolley and magnet signals match the overhead crane chart from the Canadian Centre for Occupational Health and Safety, and the stop signals match OSHA’s Appendix A; the Canadian chart shows different stop gestures, a reminder that charts vary by jurisdiction and edition. Later editions of B30.2 have been published, so confirm the chart posted in your shop matches the edition you follow.

Hoist, lower and the travel signals

Hoist and lower are mirror images: forefinger up with small circles to raise, forefinger down with small circles to lower. Bridge travel and trolley travel are the two that new riggers mix up. Bridge travel is an open hand pushed in the direction the whole crane should roll along the runway; trolley travel is a closed hand with the thumb pointing the way the trolley should run across the bridge, jerked sideways. Before the first lift of a shift, the signal person and operator should agree on which direction is which, especially if the operator walks with a pendant and may face different ways during the move.

Stop, emergency stop and move slowly

Stop is one arm extended with the palm down, swung back and forth horizontally; emergency stop uses both arms. OSHA’s Appendix A for construction cranes describes stop and emergency stop the same way, so these two signals carry across both regimes. Move slowly is a modifier rather than a motion: the signal person gives the normal motion signal with one hand and holds the other hand still in front of it. In a slab shop it is the most useful signal in the chart, because almost every set onto a saw table, cart or A-frame ends with a slow, controlled final approach.

One designated signal person

B30.2 directs the operator to respond to signals from the person directing the lift or an appointed signalperson, to be responsible for the lift when no signalperson is required, and to obey a stop signal at all times, no matter who gives it. Subpart CC says the same for construction: anyone who becomes aware of a safety problem must alert the operator or signal person by giving the stop or emergency stop signal, and the operator must obey it. The practical rule is one person gives motion signals and everyone can stop the lift. In construction, that signal person must meet 1926.1428: know and understand the signals used, be competent applying them, have a basic understanding of equipment operation and limitations, and pass an oral or written test and a practical test, with documentation available on site.

Slab-Specific Hazards Under the Hook

OSHA’s Safety and Health Information Bulletin on stone slab handling describes slabs weighing several hundred to several thousand pounds and the caught-by, crushed-by and struck-by hazards that come with them. Its recommendations translate directly into signaling practice: never stand under, near or in the fall shadow of a slab during crane moves, use a tag line to control suspended slabs, and walk at the end of the slab rather than beside its face. A signal person who is positioned correctly is also out of the fall shadow, which is one more reason to pick that spot before the slab leaves the rack.

Vacuum lifters

Vacuum lifters are below-the-hook devices covered by ASME B30.20. Inspection guidance based on that standard calls for checking the seal of the vacuum pad for debris and the condition and operation of indicators, meters and pumps before and during each lift, and for removing a lifter from service if it cannot reach its designated minimum vacuum or if any control, indicator or warning device is not working correctly. Lifter manufacturer ANVER describes a vacuum reserve and a vacuum gauge as required features, with the reserve giving more time to lower a load if power fails. For the signal person, that means confirming vacuum on the gauge before giving hoist, and having the slab raised only a few inches first so the hold can be checked. The OSHA bulletin also notes suction cups should be rated for the slab’s finish.

Clamps, A-frames and tag lines

Scissor clamps grip by squeezing the slab, so the OSHA bulletin says to place them on solid areas of the stone and not over weak veins, and not to use them on equipment operating on uneven surfaces. A-frames are where many slab incidents begin: the bulletin flags poorly designed or unsecured frames and warns that workers who stand in the fall shadow while tilting slabs upright risk being crushed. Pulling a slab from a loaded A-frame calls for a slow hoist signal, a second person on a tag line, and nobody between that slab and the rest of the bundle. Tag lines let you steer and damp swing from a safe distance; they are not a handle for holding back a slab that has started to move.

B30.2’s rules for moving the load fit slab work closely. The person directing the lift is to confirm the load is secured, balanced and positioned in the lifting device before it is lifted more than a few inches, to keep the hook positioned to minimize swinging, and to avoid sudden acceleration or deceleration. The operator is not to lift, lower or travel while anyone is on the load or hook, and should avoid carrying loads over people. Each of those points is something the signal person can see and the operator often cannot.

When Hand Signals Are Lost: Voice and Radio

Hand signals only work when the operator can see them. If the slab, a rack or a machine blocks the view, the lift has to stop until communication is restored. Subpart CC makes that explicit for construction: the ability to transmit signals must be maintained, and if it is interrupted at any time the operator must safely stop operations requiring signals until it is reestablished and a proper signal is given and understood. On remote-operated cranes, 1910.179 requires that if the control signal for any crane motion becomes ineffective, that motion stops.

B30.2 allows voice communication by telephone, radio or equivalent in place of hand signals. In construction, 1926.1420 requires radio or other electronic signaling devices to be tested on site before operations begin, transmission through a dedicated channel with limited exceptions, and hands-free reception by the operator. Under 1926.1421, the operator, signal person and lift director must agree on voice signals beforehand, must be able to communicate effectively in the language used, and each voice signal must contain three elements in order: the function and direction, the distance and/or speed, and the function with a stop command. Published summaries of the 2022 edition of B30.2 describe a similar sequence for overhead cranes. A good radio call sounds like “trolley north, ten feet, five, three, one, trolley stop.”

Special signals are allowed when the job calls for them, but they have to be settled first. B30.2 says special signals shall be agreed upon and understood by the signalperson and the operator and shall not conflict with the standard signals; Subpart CC similarly requires the signal person, operator and lift director to meet and agree on any non-standard hand signals before the operation. Never improvise a gesture in the middle of a lift.

Maintenance, Training and Long-Term Practice

Post the hand-signal chart where operators and riggers can see it, as B30.2 requires, and replace it when it fades. B30.2 also calls for the operator to test all controls before beginning a new shift and to verify the upper-limit device under no-load conditions before the first use of the hoist each shift. Build those checks into the start-of-shift routine alongside a look at the warning device, the vacuum lifter gauge and pad, and the clamps. For below-the-hook devices in normal service, inspection guidance based on B30.20 calls for frequent inspections monthly and documented periodic inspections yearly, with shorter intervals for heavy or severe service.

Training is the long-term control. Run short drills where new hires give signals to an empty hook until bridge travel and trolley travel are automatic. Rotate the signal person role so every rigger understands what the operator can and cannot see. Review every near miss with the whole crew, including the ones where somebody gave a stop signal and the operator obeyed it, because those are the system working as intended. Where crews also work on jobsites with boom trucks or mobile cranes, document signal person qualification under 1926.1428 and make sure the qualification lists each type of signaling, hand or radio, that the person is qualified to use.

For the equipment side of slab moves, browse the vacuum lifters and slab lifters and clamps collections, or look at the Aardwolf Swiftlift ASVL-380 Vacuum Lifter for Stone Slabs. Storage and transport frames are in storage racks and frames and truck A-frames, and the full catalog is at Dynamic Stone Tools.