Transforming Construction?
7.1 Data Volumes - The EPOS Analogy
Although each of the packets of information identified in Section
6.1.1 above, is in itself quite small and manageable, a large
quantity of them - thus a huge volume of data overall - would be
generated in the course of a day's work on a typical site.
Conventional planning based project management systems are simply
not capable of dealing with this, either in terms of the types of
data, or in terms of the volumes of data concerned.
But consider a large, busy supermarket. It may not be immediately
obvious, but the data intensity - the volume of data being generated
every hour, say - in such a store is of about the same order of
magnitude as the volume of data that would be generated on a large
construction project. Hundreds of people continuously interacting
with thousands of things: cans of beans in the one case, steel beams
in the other.
The difference is that, in the case of a supermarket, an enormous
amount of computing activity is going on to support the operation of
the store and its supply chain. Every time a case of product is
delivered to the store for example, a new transaction - a new piece
of data - is recorded in the store Electronic Point of Sale (EPOS)
System. Every time a packet of detergent is passed through a
check-out, another atom of data is captured and added to the overall
picture. As each tiny transaction is captured, its details are
recorded in the system to help build up a wonderfully detailed,
accurate, real time picture of activity in the store.
The imperative for the retailer is to manage stock levels as
accurately as possible. With EPOS, stock is dealt with in terms of
individual items: individual cans of soup, packets of detergent,
cartons of milk and so on. The obviously clever thing about EPOS is
the use of bar code scanners to capture data on the movement of each
of these items individually. The real key to its success however, is
the Unique Product Code (UPC) system that underlies EPOS.
In the UPC convention, every item in the entire retail universe
can be given a unique identification code. The bar code is simply a
machine readable, binary representation of the UPC. The EPOS system
is pre-loaded with all of the fixed information about the product:
purchase price, sale price, quantity in stock, supplier details and
so on. This means that at the till the only information that needs
to be captured is the fact that the item was checked out and the
date and time of the event. All the necessary sales, stock and
re-stocking information can be calculated from this.
7.2 Production Management - Construction's EPOS Equivalent
If one accepts the suggestion that construction can actually be
treated as being an orderly production environment, then the
equivalent of stock levels in construction is production levels. The
key thing to know is how much physical production is planned for a
particular period and how much is actually being achieved on a
detailed, ongoing basis. This can only be done by measuring
production levels accurately; measuring the numbers of individual
components installed, component by component, day by day throughout
the project.
Conventional, CPM based project management deals mainly with the
activities that need to be carried out in order to complete a given
project. Production management deals with the physical output
generated by those activities. Thus, an activity plan shows the
activities that will be under way, day by day or week by week during
the project. A production plan shows the level of physical output
that must be generated day by day, or week by week throughout the
project in order to complete the job on time.
The Production Management project process, as promoted by C3
Systems, is illustrated in the diagram below.
In broad terms the Production Management method works as follows.
- The starting point for the production plan is a detailed
schedule of the components of the building in question, taken
from the Building Information Model, or if a model is not
available, taken off from drawings, in the form of a "smart"
bill of quantities. Each component is identified according to a
catalogue of Unique Component Codes - similar in concept to the
retailers' UPCs - and its location and quantity are recorded.
- Each component or group of components is then allocated to one
or more construction packages. The man-hours and / or monetary cost
of installing each component are assigned according to the package
schedule of rates. In this way the 'planned value' of each installed
component, thus of the package as a whole, is established - before
construction gets under way.
- The key point about this step is that it establishes the 'value'
of all the various components of the building in common units:
man-hours or monetary cost. This is the basis on which all
subsequent calculations are carried out. Reducing everything to a
common basis of value enables comparison and aggregation of
completely different types of operation, brickwork, carpentry or
plumbing for example, over time on any given project, and,
importantly, across different projects.
- The Planned Progress curve for the package in question is
generated by spreading the man-hours or costs across the package, or
sub-package, duration according to a simple production function.
This curve shows the level of output that must be achieved every day
or every week in order to achieve the agreed package end date.
- When work gets under way the actual installation of individual
components is recorded, as it happens, preferably on a continuous,
daily basis. Every time the contractor completes the installation of
a component he 'earns' the man-hour or monetary value of that
component.
- This information is added to the production plan to generate the
'Earned value' of the work performed. The actual percent complete of
the package can then be calculated as the ratio of the earned value
to the initial total planned man-hour or monetary value of the
package. This is plotted as the Actual Progress curve. And
obviously, as all achievement is denominated in a single unit -
manhours or money value - packages can be grouped and totalled to
give group and overall project values and curves.
- It is highly desirable that when the fact of a component
installation is recorded, the man-hours used in its installation are
also noted. This enables labour usage, productivity and
effectiveness to be monitored and managed.
In general the information required to drive Production
Management is neither new nor particularly different. Dumb bills of
quantities have been in use in construction for over a century.
However, as paper documents they lack detail, flexibility and
authority. A smart bill, particularly one generated from a BIM
model, retains all of the detail of the building at the most
detailed component item level. It's flexible in that it can be used
for many purposes other than just tendering and valuation and it's
authoritative in that every item it contains can be challenged
explicitly, can thus be verified definitively.
The progress information used in production management is a
simple extract from the trade supervisor's daily diary. The man-hour
usage information can be obtained from the same source or from the
contractor's time recording system. Obviously, the Production
Management system can be used to generate turnaround documents for
the capture of this information or to drive hand held data capture
devices or similar.
There are three big assumptions behind the Production Management
approach:
- First, it is assumed that modern, new build
construction can in fact be treated as an orderly production
process.
- The second assumption is that, having deployed an optimum crew
to site, the main aim of the individual specialist contractor, is to
get his operatives up to their optimum rate of production as quickly
as possible and to keep them operating at that rate for as long as
possible until the work is complete. This means that, at the level
of the individual team or gang of operatives, production functions
(planned progress curves) will consist of distributions that are
fairly simple: linear, quarter-thirds or normal. It also means that
the principal role of the main contractor, or construction manager,
is to organise the workplace so as to enable all the various
specialist contractors to operate in this manner.
- Third, it is assumed that the production plan is not constrained
by buildability or construction logic. All output counts, regardless
of where it occurs in the building. So if one workface becomes
blocked, the crew can be redeployed without significant loss of
output.