welcome once again to this lecture in the series on principles of construction management
and today we will basically talk about planning and scheduling in construction activities
so now planning is the process of drawing up a scheme of action or execution in advance
foreseeing the likely future developments in construction industry or in planning for
a construction project it could involve choice of technology it could involve defining the
work tasks that is we break up the project into individual jobs or works
so as part of the planning exercise we try to break the project down into different jobs
or different tasks then there is this aspect of estimation of required resources we break
a job down to different activities different tasks and then try to find out for each task
or job what are the resources required in terms of manpower equipment consumables and
so on the estimation of duration is a very very critical part of our planning exercise
we must know whether a project is going to be completed in ten months or twenty months
or two months so in order to be able to do that effectively
accurately we have to have an idea of the resources that are required and whether or
not by just increasing the number of resources or just increasing the resources that we allocate
to a particular activity can we keep reducing time it may not be possible sometimes to reduce
the time beyond a certain point identification of interaction among different tasks this
is a very critical part of our understanding when we try to understand or when we try to
analyze whether we can take up one task without completing some others which tasks in a particular
project can be independently taken up if one process requires another process to be completed
for example in the kind of boundary wall example that we talked about we cannot fabricate the
angle unless the angle has been procured we cannot fabricate the reinforcing bars for
the footing or the columns unless they have been procured but once they have been procured
we can go ahead and fabricate the r einforcement cage for the footings or for the columns
so basically identification of interaction determining the inter dependencies is a very
very important part of project planning now every stakeholder in a project carries out
their own planning exercise and it is important to ensure coordination so we know that we
have talked about it at the outset of our discussion in this course a project has different
stakeholders there is the client there is a contractor there is the designer is possibly
a person who is financing the project so all these people they look at the project from
different points of view and carry out their own plans
so now their plans can be looked upon as focusing on the quality sometimes sometimes safety
sometimes manpower sometimes equipment sometimes time itself and so on so now looking at the
emphasis in construction planning construction planning is either schedule oriented or cost
oriented in the schedule oriented side we have time and resource orientation and in
the cost oriented construction planning we are most of the time talking about direct
and indirect costs associated now we talked about the different types of plans it could
be the time plan so basically what we are talking about here
is this schedule how much time it is going to take to complete an activity if we are
slipping then what should be done to cover the time and so on then there is the cost
plan how much is the project going to cost what is the kind of cash flow that we need
if we want to accelerate the project try to complete the project earlier what is the kind
of cost that we need to incur or additional cost that we need to incur and so on then
there is the quality plan a project has different activities if you consider a tunneling project
there is a boring of the tunnel that has to be done there has a stabilization of the soil
that has to be done independently we are making segments which have to be then brought and
assembled at site so now each of these activities has to have
a quality plan we should know what are the parameters to control as far as quality is
concerned for each of these activities and have a plan so that the people who are executing
those activities are aware of what are the quality control measures to be adopted similarly
there has to be a safety plan we must make sure that there is no accident at site there
is a manpower plan depending on the time of the project different kinds of people that
is people with different skills are required and we must know what is the kind of people
that are required at different points in time so that we are able to either recruit them
into the company or transfer them to that site from other sites and so on
then there is a materials plan equipment plan and a finance plan so there are different
ways of looking at the planning exercise so continuing with our discussion as far as the
project plans are concerned time plans basically refer to completing the work ahead or later
than scheduled dates may make remarkable difference in the project completion that we have an
estimate of completing the project but there may be a bonus associated with completing
the project earlier there may be a penalty associated with completing the project later
so these are things which we have to keep at the back of our mind when we are carrying
out a planning exercise in terms of time of course as i said it will affect the overall
cost of the project as far as the cost plan of the project is concerned since they take
a long time to complete it is obvious that all the funds are not required at one point
in time so we have to keep in mind the concept of
cash flow that we have talked about and contractors often fund their projects from working capital
a part of which is raised from investors bank loans whereas the rest comes from mobilization
advance and running account bills so all these things have to be carefully thought about
and foreseen so foresight is a very very important part of a construction managers job and thats
why some of these things are difficult to appreciate unless there is a real example
unless there is real experience that you have so the idea as far as this course is concerned
is to basically introduce you or expose you to some of these ideas so that you better
prepared for professional experience now coming to the quality plan and the safety
plan the focus on the quality plan is to ensure that the resource procurement construction
procedures and tolerances are within the set guidelines provided by standards of relevant
agencies so this relevant agency is very important because depending on the agency involved there
would be different tolerances that happens because the criticality of each of those projects
or each of these activities is different depending on concepts like consequence of failure importance
of the structure and so on the emphasis in the safety plan is to ensure no accidents
we must ensure that there are no accidents at site which could lead to loss of life and
property if we talk about the manpower plan it mainly focuses on estimating the workforce
and deployment of manpower in appropriate functional teams with an emphasis on optimizing
cost in time as far as the materials plan is concerned
the primary emphasis is to identify estimate procure various materials of required specifications
by minimizing their idleness in inventory we must remember that the efforts should really
be to procure the material in time for its deployment or use at site there is no point
in buying the material way in advance before it is used because that is dead inventory
that is dead cash we have should invest the money only when it is really required so an
inventory plan requires us to know exactly when a particular component or a particular
material will be required as far as construction is concerned and then taking into account
the time that it takes to procure the material some of these materials or components may
not be readily available just off the shelf so there would be a certain time for the manufacturer
of those materials to put that thing together there may be a time involved as far as transportation
is concerned so your inventory team has to have a plan of how and where these different
materials will be procured from how they will be transported to site in a manner that their
non availability does not become a reason for delay in the project as far as the equipment
plan is concerned effectively this plan focus on procurement of suitable and productive
equipment by purchasing renting or leasing in a manner that minimizes the period of idleness
of operating them at site so we should know when we need cranes what
size cranes we should know what size of welding equipment we should know what size of concreting
equipment we should know what kind of jcbs or excavators and so on and so forth now before
we proceed further with more analysis of planning and scheduling i would like to also introduce
to you the idea of a work breakdown structure now this wbs refers to a hierarchical tree
structure obtained through decomposition of the project into phases and tasks we basically
try to break down as the name suggests we break down the project into activities and
sub activities try to divide it into different classes and then try to look at the resources
required for each activity we must remember that the more thorough wbs better is the planning
and smoother is the project execution if we are able to foresee exactly how the project
is going to be executed we will be in a much better position to execute the project smoothly
if we are not able to foresee certain things then the project will be stop and go something
will happen which is unforeseen the project will stop we will make some stop gap arrangements
make the project get started again and so on
whereas if we have seen all the possibilities we know exactly the flowchart which will be
followed if this happens then what should be done if this happens then what should be
done then the execution is much more smooth and that can be achieved if we have a clear
breakdown structure with all the kinds of possibilities worked out now this is what
i mentioned the project is broken down into manageable chunks we are working from a whole
to parts kind of a philosophy and this basically is a framework for planning scheduling estimating
budgeting monitoring and controlling the project so all these important functions relating
to a project can be carried out if we have a well planned and a well done work breakdown
structure for that project now lets try to see what a work breakdown structure really
means through an illustrative example where we are asked to list the activities and create
the wbs for a road construction project and also discuss the inter dependencies of the
activities so what we are talking about is a project where a road construction has to
be carried out and what we will try to do is to break down this project into activities
of course we will stop way short of what is a final breakdown structure but i think you
will have some idea about it as far as a set of activities is concerned
lets say there are eight of these activities tree cutting general excavation grading general
areas for leveling excavation for utility trenches which is services compacting the
sub grade installing sewer lines which is services again installing electric poles which
again services and finally laying the pavement so we have broken down a project of pavement
construction into these eight activities i must point out at this stage that this is
not necessarily the only way in which this activity breakup can be done it depends on
the engineer actually as to how he defines the different activities
now another way of drawing up a work breakdown structure for this project would be as shown
here so we divide the road construction into general structures and carriageway as far
as general is concerned we talk in terms of mobilization supervising finance and accounts
as far as structures are concerned we break it up into culverts and bridges where we say
that well culverts are further broken down into excavation concreting and reinforcement
work and a similar such structure can be drawn up for bridges and when it comes to the carriageway
again there is earth work mixing and paving markings median plantation etcetera
so this shows different ways of how a work breakdown structure can be drawn up for a
given project and this facilitates planning so when we talk of culverts we can drop a
plan when we talk of markings and median plantation we can drop a plan and so on and so forth
so going back to the previously defined eight activities now lets try to see what is the
precedence relationship what is the kind of relationship that governs one activity with
respect to the other now as far as tree cutting is concerned it does not require any preceding
activity except of course what it assumes is that something what is called land acquisition
has already been completed so unless of course the land acquisition has
been completed there is no question of cutting trees in fact if you read literature as far
as road construction is concerned you will realize that actually land acquisition is
often a bottleneck as far as construction work in highways is concerned what often happens
is while constructing a road from this point to this point you may have acquired land for
this package you may have acquired land for this package you may have acquired land for
this package but there will be a package somewhere here and a package somewhere here where land
acquisition is an issue so that doesnt mean that you dont start the
construction work very often we start the construction work but hoping that while the
construction reaches this point here and it reaches from here to this point these pockets
of un acquired land will also be acquired so of course coming back to our example if
the land acquisition is cleared we can go ead with tree cutting without any preceding
activity but as far as excavation is concerned its not possible its not proper to start excavation
you cannot start excavation unless you have completed activity a which is tree cutting
as far as activities cd and e are concerned that is general grading of the area excavation
for utility trenches and compacting the sub grade they can all be started only after a
general excavation has been completed so continuing further activities f and g which
is installing sewer lines and installing electric poles they depend on c and d that is they
depend on grading general area for leveling and excavation for the utility trenches finally
the laying of pavement depends on e and f that is compaction of the sub grade and installation
of the sewer lines installation of the sewer lines because very often the sewer lines actually
run below the pavement so only once you installed the sewer lines can you complete the laying
of the pavement now from this example it is clear that there
exists an inter dependency among various works involved in a project and they can be actually
represented in a logical sequence in this case we represented it by means of a table
where we listed the different activities and had a column where we listed the required
preceding activities to have been completed before those activities are taken up now in
fact one of our earlier discussions also when we talked about the boundary wall we had given
nineteen activities as part of the breakdown of that boundary wall construction and had
left it to you to complete the or think about the inter dependency the way we talked about
just now having done this illustration on the work
breakdown structure and the concept of inter dependency lets closely look at the fundamentals
of network planning because we would like to represent the different activities by way
of a network that is so much easier to represent explain and use when we are trying to monitor
the project as the construction work goes on so before we start application of networks
to are construction scenario lets try to first we study a little bit about the network fundamentals
lets define a few terms lets talk of an activity this is an item of work that involves consumption
of resources and time of course time can also be looked upon as a resource and produces
quantitative and measurable results the activities take place between events and they have a
well defined start and well defined end so if there is an activity called digging
the trench or concreting a roof there is a very well defined start to that activity and
a well defined completion of that activity coming to that event it indicates the start
or completion of one or more activities and even does not consume any time or resource
of course there are some dummy activities which we will see when we try to see the logical
compulsions in drawing up networks and representing the inter dependencies in the form of a network
we will find that we need to have what is called a dummy activity and these activities
do not consume any resource or time and are used only to basically complete the logical
inter dependency among the different activities and what is a network its basically is a graphical
representation of activities in terms of nodes and arrows to show logical inter dependency
between activities the network helps us better understand the sequencing of activities gives
us various informations about the project such as the time required for completion of
a project the activities that need to be monitored more closely than other activities and the
basis of plans for material procurement manpower deployment cash flow and so on and of course
we can also use this whole concept to determine the probabilities of completing the project
within a certain time now there are two types of networks one is
called the activity on arrow activity on arrow means that there is an activity a and there
is this arrow between nodes i and node j so this activity a is actually represented as
ij where i represents the start of that activity and j represents the end of this activity
and a itself sits on the arrow connecting i and j so these arrows are directional so
its an i to j arrow and not j two i its not interchangeable its an activity ij which means
it starts at i and ends at j on the contrary we can have an activities on node kind of
a network where a and b are represented as nodes and there is an arrow in between which
shows the dependence that is b depends on a you cannot start b unless you complete a
so if this concept of a and b being related the way they are shown here in the activities
on node representation then what we will do here is to put b here and put a node k here
which means that a is the activity ij when this j activity is completed we can start
and b is represented as jk so the node j is the start of activity b and is also the end
of activity a so these two representations are the same except that in this case the
activities are on the node a has to proceed b in this case the activities are on the arrow
and ijk are the nodes so the activities are to repeat ij and jk
now continuing with this example there is an activity lets say digging a trench i and
j it basically represents the start of the digging of the trench and completion of digging
of the trench now going back to the previous example of eight activities lets try to see
how we can represent this information of eight activities in terms of an activities on arrow
and an activities on node network so if we look at this picture here this is an activities
on the node representation we start this project here this is activity abcdefgh and the project
ends and we can see that the information given in the previous picture a can be started without
any preceding activity not counting land acquisition because thats not part of the eight activities
that we have listed b can be started only after a has been completed cd and e can be
started if b has been completed so here its g can be started only if activity
c and b have been completed similarly f can also be started only after activity c has
been completed and activity d has been completed and h can be started if activity e has been
completed and activity f has been completed so this is how we have represented those eight
activities abcde fg and h in a activities on node network so now lets try to do the
same exercise in the activities on arrow and i leave it to you to make sure that the representation
is correct a is one two b is two three c is three four and so on and so forth
so i leave it to you to verify that a does not depend on anything b depends on a cd and
e depend on b f and g depends on c and d and h depends on e and f now here you will find
this activity here this is precisely what is a dummy activity basically to show that
g depends on both c and d the reasons for that will become clearer in some other examples
that we do later on in this course now continuing with our discussion lets try to see what are
the basic rules to be followed when drawing networks usually there is an event included
as a start of the project and an event called the end of the project each activity should
be represented with only one arrow pointing towards the direction of the progress of the
project no two activities can have the same i and j for example both a and b cannot be
represented as one two what has to be done is that we have to use a dummy activity and
try to say that well activity a is one two and activity b is one three the node one represents
the start of activity a and the start of activity b the node two represents only the end of
activity a and the node three represents the end of activity b normally it should be ensured
that j is greater than i now the following checks usually help in trying
a network the first thing being which activities must immediately precede a given activity
then which activities must immediately succeed a given activity and finally which activities
can be done concurrently so if we are able to keep track of these three issues we will
be able to draw a network now let us try to carry out this exercise using an illustrative
example where what is given is a project with four activities abc and d where a and b can
be started independently c depends on both a and b and d depends only on b must try to
construct the network we start the project with a which is one three b which is one two
they can be both started immediately and node one represents the start of both a and b node
three represents the end of a whereas node two represents the end of b
so c is the activity three four and it can start only after a and b have both been completed
but d can be started as soon as b has been completed and is the activity two four a and
b are of course activities one three and one two as is shown here so now we have converted
this tabular information into a network diagram like this lets try to do another example where
information about the activities is given as follows activities a through e five activities
a and b start independently c depends on a and b d depends only on a and e depends only
on b now for this particular situation a is lets say one two and b is one three we have
a c which is four five created with the help of two dummy activities two four and three
four nodes two and three represents the completion of activities a and b and once both these
activities have been completed we are in a position to a start activity c at node four
and four five is the activity c with five showing the completion of activity c activity
d which depends only on a is represented as two five and similarly activity three five
is the e please remember that this is not the only way of representing this information
in the table there can be another network which shows this
but one of the points that we must keep in mind when we drawing networks is that the
number of nodes should be kept to minimum the number of dummy activities that are used
that should be kept to a minimum and so on and that comes through experience as we draw
more networks as we become more adept at drawing the networks that comes naturally and with
this we come to a close for the discussion for today where we have basically tried to
introduce the concepts of networks and how to translate activities which are given in
a tabular form along with their logical preceding activities and trying to convert that tabular
representation into a network situation these books will probably help you understand the
subject matter better and i look forward to seeing you once again
thank you