The Seven Most Common Errors in CPM Scheduling

Critical Path Method (CPM) Scheduling is an invaluable tool to the construction industry. However, despite
more than 40 years of use, many seasoned professionals are still committing some common CPM errors,
errors that dilute the effectiveness of even the most carefully constructed CPM schedule.
1. Lack of buy-in by the project team.
Over the past five years, more owners and general contractors have incorporated CPM scheduling into
their construction project plans. However, their enthusiasm is not always matched by their project
team. Getting buy-in from other members of the project team such as the project manager, superintendent,
architect, and subcontractors, can sometimes prove difficult. Failure to get all parties on board
may result in a well-executed schedule that rarely gets used.
2. Personnel ill-equipped to create a CPM schedule.
CPM, when properly executed, is a sophisticated tool that can save a client considerable time and
money. However, oftentimes the contractor turns the scheduling over to an inexperienced team
member. This person may have some CPM software knowledge, but lacks the kind of seasoned
judgment that makes a plan work. The result is a schedule that contains flaws that can cause significant
problems.
3. Inadequate software for the job.
There are many CPM scheduling software packages available for purchase, some of which are
sophisticated and capable of handling multi-million dollar projects, and some of which are too simplistic
to be of use to anything but a small construction job. If your
construction project needs “serious” scheduling, such as a
$15 million school or a $50 million hospital, you need a
software package capable of delivering more comprehensive
reports and doing more complicated analyses. Choosing a
software package that is less than what is needed is a sure
way to cause scheduling problems.
4. Abuse of the scheduling software.
As the adage goes “garbage in, garbage out.” Someone who
knows how to manipulate scheduling software can wreak
havoc with a project’s successful completion. A CPM
scheduler can choose different technical options, such as
logic override, lead and lag calculations, or constrained dates
when working with the schedule. If the scheduler’s constrained
dates are artificial (chosen to create a certain result
on paper), then the CPM is useless. After all, its purpose is
to reflect realistic start and completion dates for the project’s
activities. Team members who rely on a manipulated
schedule to make decisions are misled, often with disastrous
and costly5. Inadequate incorporation of changes into the CPM schedule.
A CPM schedule is a dynamic tool. As changes are made to a construction project, the
CPM schedule must be accurately and continuously updated to reflect these changes.
Unfortunately, all too often the schedule administrator does not incorporate the changes,
or waits until the end of the job when it is too late. Regular monthly updates to the CPM
schedule, including current and proposed changes, helps ensure that the changes on
the project are correctly assessed and accommodated.
6. Lack of communication during the construction project.
It is not enough for the contractor to provide monthly updates of the CPM schedule and
to produce updated reports. If this information is not communicated to the project team,
or if the information is difficult to decipher, then the updates are useless. Oftentimes
numerous long and confusing computer reports are issued that eventually cease to be
read. One solution to information overload is a short (three- to four-page) written
management analysis report that summarizes all the CPM information—what has been
accomplished on the project, what still needs to be done, whether the project is on time
or behind schedule, and what the next critical activities are that need to be addressed.
With this kind of summary, team players are kept up-to-date with easy-to-digest and
understandable reports.
7. Failure to maintain a comprehensive schedule for claims prevention.
Over the years, the purpose of the CPM schedule has broadened from a planning and
scheduling tool to a way of protecting the project team in the event of a dispute. Used
this way, a CPM schedule can be likened to an insurance policy, because it provides a
record of a project’s construction history. This history can be invaluable when tracing
back the party responsible for a particular problem on a project. With a comprehensively
planned CPM and regular updates that contain all change orders, you have
produced a file of information that can help prevent costly claims.
Conclusion:
A CPM schedule is a vital tool for well-managed, timely, and cost-effective construction.
However, it is only as effective as it is used. Avoiding the seven errors listed here will go a
long way to ensuring a successful construction projec results.