Project Productivity and Indirect Impact to Productivity due to Project Execution
It is necessary to take into account both in terms of cost and time the effects of
productivity. While this is stating the obvious, in reality it is frequently not
taken into account to the detriment of the party that’s responsible for executing
For example let’s consider the case where a building constructor is about to miss
an important milestone and needs to accelerate his schedule by crashing critical
path activities. Say that the duration to complete 1,500 SF of exterior brick walls
for a building by a crew of 4 bricklayers now need to be completed in 7 days as opposed
to the original duration of 10 days of eight working hours each.
The total number of hours to complete the job per the original duration would be
320 manhours. One could with ease re-calculate the working hours for the crew of
4 to 12 hour days, but this calculation would be wrong since it does not take into
account productivity. Per the below productivity table a 12 hour workday for a 5
day work week results in a reduced productivity of 90% versus a regular 40 hour workweek
for the first week and a further reduction in productivity on the second week of
85%. That means that to meet the 7 day activity duration either the crew would have
to work not 12 but close to 13 hours per day for the 7 work days or if that was not
possible then an additional worker would need to be incorporated to the crew.
It’s worth noting that productivity while minimally impacted during short runs of
overtime, over longer periods of duration it is very significantly reduced.
As it can be seen productivity is a very important factor that is not fixed, rather
it is a variable pending a number of factors including the afore discussed number
of hours per workweek as well as whether the job is newbuild or a variation/ change
order (the later having a significantly reduced productivity), the height and location
of the work to be performed in the jobsite, distance and access to job staging area,
working conditions e.g. temperature and mobility, the size of project with the resulting
or lack of economies of scale, etc.
For example if a client mandates a variation/ change order to the original scope
of work to be performed, the planned project execution will have to change to accommodate
the variation and it might then be necessary to crash an activity (reduce the duration
of a critical path activity) to accelerate the project schedule. This might be as
a result of the variation’s delay on the start of a critical path activity. Consequently
there’s a productivity impact on such a crashed activity and very importantly a direct
cost impact given that the number of resources e.g. manhours required to complete
the activity will now be greater.
So in this case, the variation costs to the project are not limited to the direct
costs associated with the variation, but also indirect impacts to other activities.
Conclusion: productivity on a construction project is an important variable (with
very important cost repercussions) that results from a number of factors and can
change at any time over the duration of the project. Additionally variations/ change
orders can have a productivity impact on other activities that would have remained