Flytable Safety
There aren't many people on the street at
two o'clock in the afternoon here at Vancouver's Financial Centre.
Just a few workers heading back after a late lunch.
On January 7th, 1981, some were probably reconsidering their new year's resolutions.
Others might have been reflecting on the assassination of former Beatle John Lennon a few weeks before.
But then they heard screams, looked up, and were frozen to the sidewalk.
"I was walking along and I heard these screams and I looked up and what I
first thought to be water, something coming from the construction site,
and then I saw the helmets and realized that there were bodies coming down."
Four carpenters were standing on an unsecured flytable that suddenly turned into a giant seesaw.
They slipped off, falling 36 stories,
landing on the sub plaza area of the Bentall tower four project.
Most of you are already familiar with this method of modular construction: the flytable.
It's a reusable deck in a giant high-rise jigsaw puzzle that saves thousands of
dollars in man-hours by allowing crews to form and pour concrete flooring, story
by story, using the same pre-assembled unit leap frogging from bottom to top.
It's a great method, but it's also a breeding ground for two of your
worst enemies on the job: boredom and complacency.
For the next few minutes, we'd like to refresh your memory on safe work procedures
because we don't want history to repeat itself.
Tool box meetings
The tool box or crew meeting is the first step in safe flytable operations.
It's a refresher for old hands and a crucial learning stage for inexperienced workers.
"Well the first thing I usually do if I got to bring a new guy on the crew, I have him stand
back and watch for a first four or five tables so he gets an idea of what the guys are doing and
what has to be done so when he comes in he's not cold. You can't just throw them in there and
say 'go to it.' And then, you know, if he's not doing something right, you know, you can't do that.
So have him stand back, watch what's happening, and observe and listen. Then bring him in slowly and
he'll gradually blend right in with your crew."
At this point, completed drawings approved by a professional engineer are available to guide the crew through the assembly.
Those drawings should be clear and precise.
Once they arrive at the jobsite they cannot be altered in any way without
the approval of the engineer who designed them.
"I don't actually discuss it with the engineers, but if I see something that could be improved on or I think could be a lot safer,
I'll talk to Bud, he's the superintendent, and he would come to look at it and then make a decision on what to do."
The supervisor or foreman will point out any unusual aspects of the flytable design.
Now is the time for questions if you're unfamiliar or unsure about any flytable procedures.
"If you're not sure then, you know, back off and go talk to somebody. Find out, you know, what is happening so you're
clear when you go into it. You're not cold. You're clear in your mind what has to be done."
Preparing for that first flytable floor will set the tone for the next 10, 20, 30 levels. Safety all the way up.
Operation overview
It's really a simple concept and when carefully handled, today's
flytable systems like this one work beautifully.
After the initial flytable floor slab is poured and cured to the specified strength,
the flytable is lowered slightly to break the seal between the concrete and the plywood.
Rollers are set, lowering jacks are placed, extension legs are moved into their flying position,
and the flytable is carefully lowered further, directly onto the rollers.
Rigging is attached to pick points on the flytable top as it rolls out for lifting.
When all four slings are secure, the crane operator takes over, hoisting the flytable to the next level.
There, it's placed into position and the extension legs are lowered.
The flytable is raised to the required level for the next pouring and the process is ready to go again.
Flying preparation
That's a very brief look at the flytables leapfrog through a level.
But there are a lot of safety points which we should review. Let's go back and check them out starting at the bottom.
To begin with, don't forget about us down here, ground zero. Despite the best planning,
Fly forms can sometimes extend beyond the construction footprint when they're leapfrogging to the next level.
Traffic control must be provided when tables are flown over the street.
"Yeah when you're done telling me you've got the traffic, of course, so you've got--you have a spotter down on the ground and
when you go to pull a table out, stop the traffic, clear pedestrians, fly the table out, bring it up,
and put it in, and once the table's set down, then the traffic is allowed to go by and so are the pedestrians."
When the flytable drops away from the cured concrete slab, get under the table or stand well away.
When it comes loose, filler strips, joists, or loose forming material may fall.
If you're stripping, use your eye protection. This is also a good time to wear your ear protection.
"I'd say the most dangerous part of the operation is lowering the forms down. Not the initial dropping
the forms. It's lowering the forms down. That's when the chances of pieces falling and hitting you
are the worst. If something is going to go over the side, usually that's when it happens."
Remember to remove or secure any loose items on or near the flytable before it moves out.
Even the smallest object dropped from a height could be deadly.
Nail down or firmly attach any loose filler strips that must fly with the table.
Barricades must be installed to prevent workers from walking into areas under a flying table.
"Before you even fly the table you go over it completely.
Make sure everything's wired on or tied on. Make sure it's all secure. Just make sure that nothing
is gonna fall off and you don't wonder about it."
As the table is moved out, be aware of the location of any safety lines, conduits, or hazards that may trip you up when the table is under way.
"The next dangerous part is pushing the forms out. I've had a guy lose his finger. If the crane doesn't have the
form pulled out far enough the form will slide back in and you're pushing on it.
This gentleman that I was talking about, the form came back in, hit his finger, took the end of his finger off."
Make certain the flytable rigging is hooked up to the designated pick points. They're usually marked
with fluorescent colours for easy location. They're important and put exactly where they are to balance the load.
Most important of all, all workers at the leading edge must be equipped with fall protection.
"Oh definitely a must. I wear the full harness with the lanyard and the slider and being tied off right to the core."
One of the main recommendations of the inquiry into
the Bentall tragedy was to tie back the flytable with a rope dead-ended to a stationary object and
connecting to a flytable leg. It controls the rate of rollout of the flytable.
But don't depend on it to provide any more than emergency stability. The flytable could still roll off the slab.
"You can't assume anything. You're gonna be receiving loads or sending loads away. Don't think
that everything's gonna be all right because it was last time. Check everything, check it twice."
As the table leaves the slab the tag line should be transferred up to a man on the next level
where the worker guides the table into its landing position. Communication between the flying crew is vital.
"It's really, it's most important. That's where all your safety is, is if your crew's all set
they know exactly what they're supposed to do, and when they're supposed to do it,
and they listen to you on the radio so they know exactly what's happening.
That's where you get your safety from. Not running around, you know, wondering what they should be
doing or if they're doing something wrong. They should know what they're doing and when to do it."
By keeping in constant touch with the crane operator, the riggers, and spotters,
everyone will be aware when the flytable is underway and there won't be any surprise moves.
Flytable landing
As the flytable eases onto the next level, the topside crew guides the table into its approximate position.
The legs are lowered and pinned and the table is placed into its final position.
Here's another time to keep a careful eye on your actions so that fingers don't get caught as the jacks are secured.
The cables can now be removed from the pick points and the crane operator can reel his lines out of the area.
"The biggest thing, and I'll stress this again. The biggest thing I stress
is everybody's gotta stay alert. Everybody has to be aware of what's going on around them.
Of the guy that's beside them. And the guy that's beside them should be aware of what the guy beside him is doing.
And as long as that practice is kept, we won't get hurt."
To ensure the safety of the next level, now is the time to reshore wherever there was a jack stand holding up the fly form.
And remember if you're using a hammer to secure pins or adjust wing nuts, direct your blows
toward the building interior so there's no chance of anything, including the hammer, being propelled out and below.
If the table has a perimeter edge, the guard rails must be installed immediately.
Now the table is ready for the carpenters and other trades.
"The key to it would be, of course number one, your safety equipment being in good working order and being there,
for starters, I mean that's number one. And then communication. Communication and safety gear
and a crew sticking together. The same crew should fly the tables at all times -- not mix them up.
So that would be the three factors: your communication, your safety equipment,
and keeping your crew together so that everything is the same every time and
everyone knows their job and there's no variance."
Things have changed for the better since the tragedy at the Bentall Centre. Better safety procedures, better equipment.
But that doesn't mean we've eliminated the potential for deadly accidents. If we all remember the basic safety
procedures or ask if we're not sure, we'll all be going home after work every day.