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A Case Study on Construction Safety
Safety in demolition work Practical examples
Hello everyone, my name is Mohamad Shahid Hamkar, and I am from Afghanistan. I am faculty
in the department of civil engineering at Kardan University. I am also the founder of a private
engineering consultancy. I have over 5 years of experience in teaching, designing and consultant
and managing civil engineering in related areas. And in this short video, I will show you some
practical examples of good and bad practices, related to demolition of work. Of course, these
videos are surely for educational purposes and we are not criticizing anyone here.
(Refer Slide Time: 00:52)
Let us start with the first video.
(Video Starts: 00:54)
In this video as you can see the demolition is improper and risky, because it can potentially cause
damage to nearby structures. The workers are not using any PPE and the lives of workers are
also at risk. As these types of all can trigger the other structure members fall. Looking at these
cracks over here, it looks like the whole building is not in good condition. The state of the
building is so bad, that they could not even remove these windows first.
And you have to be very careful with the electric poles near the structure, like the one here. And
these are some of the access equipment, which one can use during the demolition work.
(Video Ends: 01:46)
(Refer Slide Time: 01:47)
(Video Starts: 01:48)
This is called wrecking ball demolition and the steel ball can weigh up to 6500 kg. So, you can
imagine its impact energy. You know that demolition is a highly destructive activity. At this
video demolition is been carried out with other activities going on nearby. You can see the
movement of vehicles around the area. Actually, the entire area should have been isolated,
barricaded and restricted from entering.
So, you have to be very careful and guard all the blind and hazardous spots of a machine. And
these are some of the equipment used for breaking and cutting concrete.
(Video Ends: 02:40)
(Refer Slide Time: 02:41)
(Video Starts: 02:41)
In this video again, the entire area should have been isolated. They should have stopped the
traffic for some time or should have properly planned this. And these are some of the tools used
for cutting metal.
(Video Ends: 03:00)
(Refer Slide Time: 03:01)
(Video Starts: 03:04)
This is the practical example of a near mess. As you can see the wall is been demolished without
following any standard procedure. Even if it had to be demolished manually, the workers should
follow a proper method. This demolition is totally unplanned and put the lives of the workers at
risk of fatality. Also, the workers are not using any PPE.
(Video Ends: 03:16)
(Refer Slide Time: 03:33)
(Video Starts: 03:35)
In this video the worker case out the wall’s demolition in the right way. But there is no regard for
his own safety. It is like he is cutting the branch of the tree on which he is sitting. There is no
scaffold or staging system to support him. And again, he is not using proper PPE and fall
protection system or personal fall risk system. So, this is not a good practice at all.
(Video Ends: 04:07)
(Video Starts: 04:10)
In this video as you can see the sudden fall of the wall, could have triggered the fall of the floor
on which it fell. The worker performing the demolition is not equipped for his safety and there is
no measure for dust control.
(Video Ends: 04:33)
(Video Starts: 04:38)
In this video no dust control measures have been taken even though the workers are near the
demolition site. Also, demolition of this left out part of the structure could endanger the adjacent
structures.
(Video Ends: 05:04)
(Video Starts: 05:08)
In this video, the demolition is happening close to the workers. You can see how simply he is
jacking up the whole brick wall, without taking any safety measures.
(Video Ends: 0522)
(Video Starts: 05:27)
Demolition in this way can trigger the collapse of the entire structure at once, due to the impact.
Hence it can lead to the fatality of the workers, working on the structure members without any
support. See how these workers are working at such height without using any personal fall risk
system.
(Video Ends: 05:55)
(Video Starts: 06:00)
Here the worker is wearing PPE, but he is working at the edge of the structure without fastening
the harness. Hence the PPE will prove to be of no use, incase of a fall. And I think, work harder
is good, but you have to be smart enough. So, work smarter is better.
(Video Ends: 06:23)
(Video Starts: 06:29)
Here you can see that someone only destructed the columns at specific point. Let me show you
that. I am talking about these points. And because the columns are no longer able to resist the
load, the structure collapses. And at this demolition the problem is that the collapse might
happen during the destruction of those columns. I mean when the person uses hammers or
drillers and might lead to injury or fatality. And no measure to control the dust is another big
problem here.
(Video Ends: 07:16)
(Video Starts: 07:22)
(Refer Slide Time: 07:22)
This is an example of building implosion. In a building implosion, the strategy is to place the
explosive materials and timing of its detonation and then detonate so that the structure collapses
on itself. Please note that these blue objects are some water containers. And what they did is that
they exploded these water containers first as you can see here and then the structure to minimize
dust.
(Video Ends: 08:01)
These areas I mean openings are wrapped with fabrics to avoid flying concrete. And you have to be even more careful when you demolish prestressed concrete members. Some of the important considerations that must be taken into account when planning or building or other structures implosion or controlling fly, the detonation of charges, crowd control, dust control and clean up.
That is it and thank you.