Signals and communication

A crane operator often cannot see the load, the landing point or the people near it. The boom, the building, the load itself or simple distance block the view. In those moments the operator is effectively blind and depends entirely on someone else's eyes. Clear, agreed, reliable signals are what make a blind lift possible. Confused or missing signals are what turn it into an incident.

This lesson explains when a signaller is needed, what qualifies someone to signal, the standard hand signals, the rules for radio and voice communication, and the habits that keep communication working through a whole lift. It is awareness training: anyone who will signal cranes needs the specific training and qualification required where they work.

When a signaller is needed

Canadian rules require a signaller whenever the operator's view of the load, the load path or the equipment's travel is obstructed, or when the equipment or its load could endanger someone. In Ontario construction, the employer must appoint a competent worker as signaller, give oral training and oral and written instructions, keep the instructions on site and provide high-visibility apparel; the signaller must not do other work while signalling, must stay clear of the path, keep it in view and stay in the operator's full view. Alberta's code addresses hand signals for cranes in section 71 and requires a designated signaller where the operator's view is obstructed.

In practice, most lifts on busy sites need a signaller at some point: when the load goes over a roof parapet, behind a building, into a shaft or onto a floor the operator cannot see. Even when the operator can see the load, a signaller can watch the swing radius, power lines and people that the operator's attention is not on.

Who can signal

A signaller must know the signals, understand how the crane responds to them and be able to see both the load and the operator, or be in reliable radio contact. They must be able to judge distance and speed, recognize when the load is getting close to an obstruction or a person, and stop the lift without hesitation.

In Canada, the employer decides whether a worker is competent to signal, and must be able to show the training and instruction provided. Many employers use third-party rigger and signaller courses, and some owners require them. The signaller's garment, often blaze orange with reflective stripes in Ontario, helps the operator identify the one person giving signals.

One signaller, but anyone can stop

Only one person should give movement signals to a crane at any time. If two people signal, the operator may follow the wrong one or freeze. The one exception is the stop signal: anyone who sees danger may give a stop or emergency stop, and the operator must obey it immediately, whoever gives it.

Canadian codes and CSA Z150 follow the same principle, and Alberta's code requires operators to obey all stop signals regardless of who gives them.

Standard hand signals

Standard hand signals for mobile cranes are published in ASME B30.5 and CSA Z150, and OSHA's Subpart CC Appendix A reproduces the standard method. Overhead cranes have their own set in ASME B30.2 and CSA B167. The most important signals are shown below. A chart of the signals in use should be posted on or near the crane.

Signals must be given clearly and continuously while the motion is wanted. When the signaller stops signalling, the operator stops. An unclear signal should get no response: the operator stops and waits for a clear one. Directions such as left and right must be given from the operator's point of view, which is why swing signals point in the direction of movement rather than using words.

Non-standard signals should be avoided. If the work involves a motion or attachment the standard signals do not cover, the operator, signaller and lift director must agree on any special signal before the lift and record it in the plan.

Where the signaller stands

The signaller's position is a safety decision in itself. They must be where they can see the load, its path and the landing area, and where the operator can see them clearly. They must also be safe: outside the fall zone, clear of the swing radius and pinch points, not walking backward near edges, and protected from traffic. High-visibility gloves and clothing help the operator pick out the signaller's hands against a busy background. If no single position gives a view of both the load and the operator, the lift needs radio communication or a relay arrangement.

Radio and voice signals

When the operator cannot see the signaller, radios carry the signals. Radio communication brings its own failure modes: dead batteries, crossed channels, noise, dead spots and misunderstandings. Good radio practice addresses each of these.

• Test the radios at the lift location before the lift starts.
• Use a dedicated channel that nobody else uses during the lift.
• Identify the crane at the start of each instruction if more than one crane is on the channel.
• Give each instruction as function, direction, distance or speed, then the stop: for example, hoist up, ten metres, five, three, one, stop.
• Keep talking during blind movements so that silence means stop.
• Agree on what the operator does if communication is lost: stop all motion and wait.

Canadian employers usually set radio procedures in their lifting programs, often following CSA Z150 guidance and IHSA or provincial safety association material.

Reaction time matters

Every signal takes time to work. The signaller has to notice the problem, give the signal, and the operator has to see or hear it, understand it and move the controls. Then the crane takes time to stop. During all of that, the load keeps moving.

Communication beyond signals

Signals are the last link in a chain of communication that starts with the lift plan. The pre-lift meeting is where everyone learns the plan, agrees on signals and channels, identifies the signaller and confirms that everyone understands the stop rule. Language matters: signals and instructions must be understood by everyone involved, and workers who share a site may not share a first language. Noise from generators and traffic, glare at sunrise and sunset, rain and darkness all degrade communication and should be planned for, for example with better lighting, headsets or a pause in nearby noisy work.

When communication is lost or unclear, stop. That rule is simple and easy to remember, and it prevents most communication failures from becoming incidents.

Signalling overhead cranes and hoists

In plants, overhead cranes are often operated from a pendant or a radio remote by the same person who rigs the load, so there may be no separate signaller at all. That person must be able to see the load, its path and the people near it throughout the lift. When the load must travel out of the operator's sight, for example around a column or into another bay, a second person should act as signaller using the overhead crane signals in ASME B30.2 and CSA B167, which differ in some details from mobile crane signals; bridge travel and trolley travel, for example, have their own signals.

Plants should post the signal chart near each crane, train every authorized user in it and make sure the warning horn or light is used before travelling a load through an occupied area. Where many cranes share a building, labelling each crane and its remote clearly prevents a user from moving the wrong crane, a surprisingly common cause of incidents. Supervisors should watch for informal habits, such as waving a load along with a hand gesture nobody agreed on, and correct them before they become the norm.