54 CHAPTER SEVEN
and instinct are perhaps the best quality. When the condi-
tions slow the progress of the work, a productivity factor
greater than one is used, thus increasing the number of labor
hours to complete a unit of work. When the conditions
increase the speed at which the work progresses, a produc-
tivity factor less than one is used, thus decreasing the num-
ber of labor hours to complete a unit of work. Following are
some variables that need to be considered when determining
the productivity factor.
Availability and Productivity of Workers. When
there is plenty of work available and workers are scarce, less-
trained craft persons are accepted. These less-trained per-
sons will require more time or labor hours to complete the
required task, and a productivity factor greater than one is
used. Conversely, when construction projects are scarce,
workers may become motivated, and the contractor can be
selective and hire only the most qualified workers. This will
result in producing more work per labor hour, and a pro-
ductivity factor less than one is used.
Climatic Conditions. Cold, hot, winds, rain, snow,
and combinations of these all affect the amount of work
that can be produced in an hour. Typically, any weather
extremes will slow down the work pace and may require
additional precautions that add labor hours to the project.
The estimator must try to factor in each of these to deter-
mine the most cost-effective approach. Can the project be
scheduled so that the concrete can be poured before the
winter cold sets in? If not, extra time and materials will be
necessary to make certain that the concrete does not freeze
after it is poured. On the other hand, if the weather is too
hot, precautions will need to be taken to ensure that the
concrete does not set too quickly, requiring provisions to
be in place to keep it damp. Adverse weather conditions, in
and of themselves, do not warrant the use of a productiv-
ity factor greater than one. The anticipated weather condi-
tion must be worse than the average weather condition for
the historical data. For example, if the historical data were
for concrete poured during the winter months, the histor-
ical data already take into account the time it takes to pro-
tect concrete against the average winter conditions.
However, if the historical data used were for concrete
poured during the summer months or all year round, a
productivity factor greater than one is used to account for
the winter conditions. A productivity factor of less than
one would be used when the anticipated weather condi-
tions are better than the average weather conditions for
the historical data.
Working Conditions. The job site working conditions
can have a great effect on the rate of work. A project being
built in the city with little working space, limited storage
space, and difficult delivery situations typically has less
work accomplished per labor hour just due to the difficulty
of managing the resources. The same may be true of high-
rise construction where workers may have to wait for the
crane to deliver materials to them, have difficulty moving
from floor to floor, and take extra time just to get from
where they punch the time clock to where they will be
working. Again, a productivity factor of greater than one is
used when conditions are worse than average, and a pro-
ductivity factor of less than one is used when conditions
are better than average.
Projects that are far removed from the supply of
workers and materials often have similar situations that
the estimator must consider. How can material deliveries
be made in a timely fashion? Where will the material be
stored until needed? Will extra equipment and workers be
required to transport the material from the storage area to
where it will be installed? Will storage sheds be necessary
for material that cannot be left out in the weather? If so,
who will be responsible for receiving inventory and mov-
ing it to where it will be installed? Worker availability for
remote jobs must also be considered. Are workers avail-
able, at what costs, and are any special incentives required?
Again, a productivity factor of greater than one is used
when conditions are worse than average, and a productiv-
ity factor of less than one is used when conditions are bet-
ter than average.Other Considerations. Workers seldom work a full
60 minutes during the hour. Studies of the actual amount
of time worked per hour averaged 30 to 50 minutes. This is
often referred to as system efficiency. Keep in mind that
the time it takes to “start up” in the morning, coffee
breaks, trips to the bathroom, a drink of water, discussing
the big game or date last night, lunches that start a little
early and may end a little late, and clean-up time all tend
to shorten the work day. This list of variables is long, but
these items must be considered. Again, the productivity
factor is based upon the variance from average conditions,
not from the ideal. A system efficiency lower than average
will require a productivity factor greater than one, and a
system efficiency greater than average will require a pro-
ductivity factor less than one. Of most importance to the
estimator are those items that can be done to make it “con-
venient” to work, such as placing restrooms, drinking
water, and materials close to the work. This also involves
providing adequate, well-maintained equipment; seeing
that materials are delivered to the job just before they are
needed; answering questions regarding the work to be per-
formed in a timely manner; and anything else necessary to
ensure that the work can proceed quickly.
When keeping historical records for the labor produc-
tivity, it is important that a record not only of the produc-
tivity rate be kept, but also under what conditions that
productivity rate was achieved so that an appropriate pro-
ductivity factor can be used.