Accidents in construction industry – II

Accidents in construction industry – II


and welcome once again to the series of lectures
on principles of construction management and in the last couple of lectures we have been
talking about construction safety and in the last class we had talked about some specific
considerations or reasons because of which construction sites are more vulnerable to
accidents we will continue that discussion today and talk about some special topics which
was left out from the last class now before we do that i must once again acknowledge the
help and support and the material received from my colleagues in the construction industry
and i must admit that a lot of information presented in this lecture is actually based
on actual events at different sites and actual safety related documents of a few construction
companies and this information is being shared only for educational purposes to create an
awareness towards construction safety moving on this was our agenda for the last
class we have covered housekeeping right down to lifting and rigging and what was left for
a subsequent discussion was some special topics now before we go to special topics and start
discussion today let me show you some pictures of construction sites drawing from the kind
of classification we had done last time so here are two pictures which show an extremely
cluttered site and you can imagine that working in these sites is an additional challenge
than working in normal environment to self the picture on the left has bars lying all
over the place and the workers have to be very careful to avoid tripping on these bars
as they move carrying a bar from one place to another
similarly the picture on the right is another cluttered site compare to these sites lets
look at a site like this where there is construction material there is scaffolding plates there
are all kinds of materials but they are nicely start at one place barricaded and the passage
where people have to move is clearly defined and very neat the same is the situation in
the site on the right so we can see that these places where there are bars are sticking out
and so on that has been nicely barricaded so that nobody really works into an area which
is more hazardous you will recall that we discussed safe work practices as far as excavations
are concerned and these are pictures which show shoring and struts to support the shoring
and providing access using ladders so you can see with this ladder extends beyond
this point of rusting as far as the shoring is concerned when you had spent some time
talking about working with ladders so here we see some safe practices while working at
heights with ladders and this picture here especially shows us how to handle a ladder
so there is ladder should extend the meter beyond this point there is working between
the styles there is ladder secured at the top which is being shown here there is an
additional point of contact for the ladder which is given here the ladder on the level
surface is secured at the bottom and so on so its required that we spend enough time
and effort to identify the kind of precautions that we need to take or that we can take at
a construction site to prevent accidents continue with our discussion on ladders here we see
a correct use of the ladder and an incorrect use of the ladder so you can see that this
is a bad practice something which the workers need to be trained not to do similarly if
we see this slide here also is an example of the right way of working with ladders and
the wrong way of working with ladder facing directly towards the steps facing the work
activity and steps being side on as far as the work activity plane is concerned makes
a lot of difference when it comes to safe working with ladders
continuing with our discussion on working with heights here we can see instillation
of safety nets in a big way as far as a building construction site is concerned and this picture
here shows us what are the different design considerations or theoretical considerations
that go into the design of a harness so moving on here we see some unsafe electrical work
practices at site it could be non isolation of electrical parts it could be defective
cords and wires it could be the cover not been provided on the junction box or it could
be an unused opening which is not closed all these becomes sources for increase in the
vulnerability and susceptibility as far as accident is concerned now lets come back and
continue our discussion on some special considerations or special topics in construction safety as
far as their relevant from the point of view a construction site
so first thing that we take up today is cutting and bending of reinforcing bars engineers
and supervisors should prepare a safe work procedure and train and educate workers before
commencement of work and only trained and authorized personnel should operate the machine
the bars should be arranged with enough access way for workers to be moving around you recall
that one of the first slide that i showed for a poor housekeeping slide involve basically
workers moving around with reinforcing bars and this is precisely whats been talked about
here that we must arrange and provide for an appropriate access way so that the workers
who have to carry the bars for bending to the machine can do that without the danger
or with the minimum danger of tripping as far as the operation itself is concerned of
bar bending the operator and helper must have a good communication its important that we
understand each others methods of work and the sequence of operations that each of them
has to perform the helper should be trained to do the task
the operator should ensure that the helpers hand is clear from the moving parts i leave
you with the food for thought the diameter of bars used in the construction industry
special in the heavy construction try to find out what is the diameter of the bars involved
and then try to find out the unit weight of bars of different diameters why i am giving
this assignment is basically that once you understand a per meter length of the bar of
different diameters especially in heavy construction maybe let say thirty two mm or even twenty
five mm for that matter you will realize that handling a bar requires a fair amount of strength
and a fair amount of effort much poor so the effort involved or the power involved in the
machines when they are bending these bars or cutting these bars is phenomenal and in
case there is any accident it could be a serious debilitating accident as far as the workers
are concerned so please understand please do try to find out the diameters used in the
heavy construction and the unit weight of the bars the length of the bars which is available
at sites most of the time and how it is actually assembled when it comes to reinforce concrete
construction now this picture here shows a very good practice
of shielding the protruded ends of a reinforcement at site here another example of hazard a situations
in construction site is confined spaces any space having limited access or egress when
subjected to hazards like deficiency of oxygen toxic and flammable gasses or substances dust
etcetera would qualify to be a confined space examples for this would be pipes vessels tanks
silos trenches and ducts you will recall the two slides that i showed you about the excavation
work but the picture on the right was something which could qualify as a confined space especially
if you are working let say three meters four meters or five meters below the ground so
i call upon you to find out what is the technical definition of a confined space and at the
end of it it becomes a judgment that no matter what the definition is if there is a reason
to believe that there will be limited access or egress if the opportunity to the worker
to leave that place in case of an emergency is limited that place becomes a confined space
and if it becomes a confined space the rules governing confined space handling become operational
that is something which is a construction manager as a safety officer or a safety professional
one must be aware of as far as the hazards in the confined space
are concerned it could be oxygen deficiency or enrichment presence of toxic or flammable
gases chemical hazards fire hazards electrocution heat or cold caught in between moving equipment
poor lighting and so on so there can be a situation where if in a confined space we
suddenly see a moving equipment there is no place to escape and that becomes a death trap
more or less similarly there would be challenges arising out of poor lighting in confined spaces
so these are the kind of things which we must address when we are talking of confined spaces
and the challenges posed in terms of safety preventive actions in this case would be appropriate
permits check at entry access and ventilation check levels of oxygen and flammable vapour
and toxic gases entry book and supervisors present continuously at working place use
proper ventilation and ladder if required use only twenty four volt lamp for elimination
display boards for confined space work being done power tools used in confined spaces must
be insulated and provided with proper earthing ensure presence of proper fire fighting and
rescue teams good communication between the workers in the confined space and outside
and finally use the required ppe these are some of the examples of confined spaces and
we can see man wholes tunnels and pipes has definite examples of people having to work
in confined spaces moving forward lets talk about what is called hot work in the construction
industry and hazards in this area would be heat electrical hazards cutting and welding
and radiation a kind of preventive action that we talk about in these conditions would
include read and understand the contents of the permit and follow them in letter and spirit
i would like to draw your attention to the word permit which has been often on as far
as our discussions is concerned so this is a system by which an announcement
is made appropriate approvals are taken for a particular work to be undertaken in a particular
area so there is a large site a certain area and if we want to carry out certain work it
could be confined space it could be working at heights it could be hot work in a certain
area then there has to be a system in place so that approvals have been taken and other
people informed of that nature of work being done for a particular period of time check
the area to prevent fire because in case of hot work its extremely vulnerable for fire
check gas cylinders and apparatus for leak hot work often involves working with flames
and for that we often use gas cylinders and we must ensure that they are not leaking when
welding be sure that masks are used and the area is barricaded check fire hazards to prevent
fire ensure the presence of an operator and fire extinguisher confine fire spark range
with proof sheet and do not place combustible materials in the fire spark range and lets
continue with this list we must ensure proper ventilation inspect and check proper earthing
welding cables gas cutting hose machine regulator and so on may provide proper welding and gas
cutting booth which could be made with a g i sheet with weather protection that basically
says that in the site we isolate an area provide a lot of the right infrastructure in that
area but that sometimes is possible sometimes its not possible and it depends on individual
conditions gas cutters should be provided with gas friction
lighters and matches should not be used check all fitting such as gauges flashback arrestors
non return valves gas cylinders and cutting torches proper use of proper personal protective
equipment safety shoes helmet hand gloves goggles face shields etcetera we will talk
about the specific ppes and their specifications in a subsequent lecture but the spirit of
it i am sure is clear to you and these pictures here show you two examples of hot work in
one case you are talking of bituminous construction and another case we are talking of pipe welding
and grinding and we can see a lot of sparks flying around so you can imagine that these
sparks pose a major hazard as far as fire is concerned and effort needs to be made to
confine these sparks to a local area similarly when working with hot bituminous
mixes one has to be very careful to protect your feet with the use of proper books and
in order to warn people that the worker may be working its also important that people
in the neighborhood or near this work site are also warned that this is hot work and
thats why we need a placard like this which is shown because the worker working with bituminous
mixes or the hot bituminous mix would be wearing the right kind of ppe but not necessarily
a passerby not necessarily a person not directly involved with the work and if he is not wearing
that protection that person might get injured causing an accident as far as the construction
site is concerned so moving forward lets spend some time on
falling objects we talked about it briefly last time cover up all the openings because
they become the source for objects to be falling through and hurting somebody or hitting somebody
down below debris and other materials can fall through these openings and hurt someone
below do not throw debris or waste materials from height its a very bad practice because
somebody at the top may not necessarily know if there is somebody walking around at a lower
level or because of the action of wind and so on the place where you are targeting the
debris to get deposited might change and hit somebody where you thought the debris would
not even reach wear your safety helmet all the time use entrances that are provided with
overhead shelters do not go under suspended loads prevent tools from falling by placing
them in a suitable toolbox and provide suitable toe boards dispose of debris down the chute
provided it depends on the kind of debris it depends on the amount of debris we may
have to construct a chute through which the debris can be just dumped from the top and
it reaches the bottom the chute also becomes an environmental protection measure because
it localizes any dust going into the atmosphere another special conditions as far as construction
sites is concerned is the use of machines we cannot live without using machines at a
construction site and we have to observe certain precautions all machinery must be securely
fenced so that they do not fall do not used machines with an exposed dangerous spot hands
should never be placed near a machine with rotating parts whether its a peddles to fan
or any such machine make use of push sticks when pushing at timber across a circular blade
check that hand tools are in good condition before use all the effective tools must be
reported to the supervisor its important from the employers point of view where all tools
and tackles are maintained and defective tools are not used but at the same time it is the
employees responsibility it is the workers responsibility to ensure that the tools that
we are working with are shown proper respect the tools should not be miss handled and used
for purposes other than what they are meant for only then will they have a long life and
here are some of the pictures of using safe practices when handling machines chemical
cleaning is another area which has a small application as far as construction safety
is concerned at sites and the hazards involved are pollution of
the environment toxic gases and machinery or equipment hazards and the preventive measures
were obviously include work permits barricading of work area display of sign boards checking
of all the flanges nuts bolts valve and connections before and during the work inform all nearby
employees and workers use of proper ppe such as hand gloves safety shoes helmets and if
there any choke lines of valves then use a wooden hammer and remove the obstacle its
important that it is ensured that all the lines are free they are not choked we will
not spend too much time on fire fire is a major hazard at construction sites and could
cause major injuries to people and destroy property leading to serious disruption of
work poor safety practices include allowing overheating of machineries in proper storage
of flammable and combustible liquids and hot work which is welding and cutting and preventing
measures would include adequate fire safety training effective measures for all hot work
good maintenance of electrical equipment restriction of smoking only to smoking areas storage and
cleanup of combustible and flammable liquids and regular inspections of course fire engineering
and fire safety is a very vast topic and i am touching upon this only for the sake of
completeness and we would probably need an entirely different course to talk about the
hazards of fire and how it is handled from an engineering point of view as far as manual
handling is concerned very often we have workers and labour handling heavy loads having very
specialized kind of loads please remember that even handling a twenty kg bag is not
easy a twenty kg bag handling versus reinforcing bar which is spanning let say three four five
meters having the same weight are two different things
and therefore if not properly taken care of manual handling could lead to injury and pain
in the lower back and hand injuries so here we are talking of not only accidents here
we are also talking about health of worker and health is also one of the very important
assignments or it is very much within the scope of work as far as safety is concerned
so the safety group is charged not only with the responsibility of ensuring that there
is a safe environment for working which is accident free but also charged with the responsibility
of ensuring that the environment is such that long term effects such as pain in the lower
back they do not come and haunt the workers for preventive measures could include proper
training in handling load using mechanical aids where possible and taking help if load
is heavy and wearing appropriate ppe and periodical medical checkups close the discussion for
today i would leave you with a problem for in fact two problems
lets consider the following scenarios in construction project pressure testing of a pipeline and
painting we have in this discussion today and in the previous class talked about specific
scenarios excavation hot work confined spaces welding and so on so i am giving you two scenarios
pressure testing of a pipeline and painting pressure testing means that we have set up
a pipe line which has several joints and finally what we want to do is to put a (( )) here
(( )) here and try to fill this pipeline with the fluid and apply pressure so we want to
make sure that the pipes are in good condition the joints are in good condition and the pipeline
itself is worthy of views it needs the requirements so this is what is accomplished or this is
what is the object of carrying out what is called a pressure test of a pipeline similarly
there could be a situation where we are painting a large tank in these two cases list the hazards
involved and measures that can or should be taken to minimize the possibility of an accident
while working so much the same way as we have done in the
previous slides try to do these two assignments on your own and try to figure out how we can
work or how should we work when we are working for these two cases with this we come to our
close for the discussion today and here is a list of references which will help you understand
the whole idea of construction safety and construction safety management better and
i look forward to seeing you once again in a subsequent discussion
thank you

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