Aerial work platforms, including scissor lifts and boom lifts, are often the safest way to work at height, but they bring their own hazards: tip-overs, falls from the platform, crushing against overhead structures and contact with power lines. Safe use comes down to choosing the right machine, inspecting it before each shift, setting it up on suitable ground, using the right fall protection and having trained operators.
Types of platforms and how to choose
Aerial work platforms, also called mobile elevating work platforms (MEWPs), come in several forms:
- Scissor lifts raise the platform straight up and are common indoors and on level sites.
- Boom lifts, either telescopic or articulating, extend the platform up and out to reach over obstacles.
- Vertical mast lifts and personnel lifts suit tight spaces and light work.
- Vehicle-mounted platforms such as bucket trucks are used for utility and sign work.
In Canada, the CSA B354 series of standards covers the design, use and training for these machines. Provincial rules refer to them in different ways, so check the current editions and the requirements where you work.
Choosing the right machine
Many incidents start with the wrong machine for the task. Before choosing, consider:
- The working height and horizontal reach needed
- The total load on the platform: people, tools and materials
- Indoor or outdoor use, and the machine's wind rating for outdoor work
- Ground conditions and slope, and whether the machine is rated for rough terrain
- Floor load capacity, especially on suspended slabs, parking structures and mezzanines
- Overhead obstructions, doorways and access routes
- Proximity to power lines and other energized equipment
Before each shift
The operator should complete a pre-use inspection following the manufacturer's manual, and record it as your program requires. A typical inspection covers:
- Operator's manual and capacity and warning decals present and readable
- Guardrails, gates and toe boards secure and undamaged
- Anchor points for fall protection on boom lifts intact
- Tires, wheels, outriggers and stabilizers in good condition
- No hydraulic leaks, damaged hoses or loose fittings
- Battery, fuel and fluid levels
- Function test of all ground and platform controls, emergency stop and emergency lowering
- Tilt alarm, descent alarm and other safety devices working
A machine with a defect is tagged out and reported. The operator should also do a workplace inspection of the area where the machine will be used: holes, drop-offs, slopes, soft ground, debris, overhead hazards, power lines, traffic and other people.
Power lines. Contact with overhead power lines is one of the most serious hazards for boom lifts. Each province sets minimum limits of approach based on voltage, and electricity can arc across a gap. Identify lines before setting up, keep the whole machine and anything it carries outside the limit, and contact the utility where work must be closer.
Fall protection on the platform
Guardrails are the primary fall protection on a platform. Workers should keep both feet on the platform floor and never climb, sit or stand on the guardrails, or use ladders or buckets to gain height. On boom lifts, a worker can be thrown from the platform by a sudden movement, so a full-body harness connected to the manufacturer's designated anchor point inside the platform is required in most provinces and by manufacturers. Use a lanyard short enough to restrain the worker within the platform where practical. For scissor lifts, requirements to wear a harness vary by province and manufacturer, so check both. Never tie off to an adjacent structure from a platform unless the procedure for exiting at height has been specifically planned.
Operating safely
- Operate only machines you are trained and familiarized on.
- Stay within the rated load and the wind limits, and stop work when conditions exceed them.
- Drive with the platform lowered unless the manufacturer allows elevated travel, and watch for holes and slopes.
- Watch overhead when raising or moving to avoid crushing against beams, ducts or ceilings.
- Keep the area below clear and use barricades where needed.
- Know how to lower the platform in an emergency from the ground, and make sure someone on the ground does too.
Common incidents and their causes
| Incident | Typical causes | Prevention |
|---|---|---|
| Tip-over | Driving onto soft ground, a slope or a hole; overloading; high wind; extending beyond the rated reach | Walk the area first, stay within load and wind ratings, use outriggers where fitted, follow the load chart |
| Fall from the platform | Climbing on rails, leaning out, being thrown when the boom moves suddenly, gate left open | Feet on the floor, gate closed, harness and short lanyard to the platform anchor on boom lifts |
| Crushing against a structure | Raising or travelling without watching overhead; operator pinned against the controls | Plan the path, raise slowly near obstructions, use machines with secondary guarding where available |
| Electrical contact | Boom or materials entering the limit of approach of an overhead line | Identify lines, mark the zone, use a spotter, contact the utility |
| Struck by falling objects | Tools or materials dropped from the platform | Tool tethers, toe boards, barricade below |
Setting up: a short sequence
- Walk the work area and the travel route, looking for holes, slopes, soft ground, floor load limits and overhead hazards.
- Position the machine so the work is within reach without extending to the limit or travelling while elevated.
- Set outriggers or stabilizers where fitted and confirm the machine is level within its limits.
- Barricade the area below and confirm a trained person on the ground knows the emergency lowering controls.
- Connect the harness to the platform anchor before raising, and keep it connected until the platform is back down.
A common shortcut is skipping the walk-around because the machine was used in the same spot yesterday. Floor openings get cut, materials get stacked and ground softens after rain, so the check is worth repeating every time.
Training and familiarization
Operators need training covering the hazards, safe operation, inspection and fall protection for the class of machine, plus familiarization on the specific make and model they will use. Supervisors should confirm both before anyone operates a machine, and keep records. See Keeping safety training records. A platform is also often the rescue tool for a fallen worker, which ties into your fall rescue plans.
How ehZee can help
We review how aerial work platforms are selected, inspected and used on your sites, check training records, and write procedures that fit your work. See our lift safety and fall arrest service, and A ladder inspection checklist for other access equipment.
Common questions
Does a scissor lift operator need to wear a harness?
It depends on your province, the manufacturer's instructions and your company's rules. Guardrails are the main protection on a scissor lift. Where a harness is required, connect only to the anchor point the manufacturer provides.
Who maintains the machine?
The owner or rental company is responsible for scheduled maintenance and periodic inspections by qualified people. Operators handle the pre-use inspection and report defects.