What makes construction different from manufacturing is its dynamic nature. Unlike a systemized production plant, a construction site is a mesh of interconnected processes that are far from optimized. The traditional top-down planning practice does not solve problems on the construction site, as recent research reveals. Making planning collaborative is a necessary step in making construction less wasteful.
Everybody
in the industry has felt frustration with inefficiencies in construction, but seeing
the data is still disconcerting. I’ve had the pleasure of attending several
workshops organized by the Finnish Aalto University’s research teams. These
eye-opening events both revealed how much waste we have in construction today
and suggested solutions to this problem.
Four Aalto
University graduate students shared insights from their research at a workshop of
the Waste Workgroup of the Building 2030 consortium. They
focused on projects where takt production, a lean construction method, had been
used. Takt production breaks the work down into equally timed work batches and typically
shortens project lead time considerably—up to 50%. However, even these
well-planned projects included waste and unnecessary movement, as the
researchers found out.
Even the Best Plans Can Be
Made Better
Saara
Salerto of Skanska used
video equipment to record the activities in two corridors of the Urban
Environment House construction site in Helsinki. She measured the utilization
rate and possible work disruptions for six weeks. It became evident that the
work did not follow the original takt schedule. For example, in the third week,
only one task was supposed to take place in the area. Instead, two other tasks
were still in progress, one of them starting early. In addition, three
unplanned tasks went forward in the area.
During the
busiest days, up to four contractors worked in the same area, but some of these
just for a few minutes. After the rush period, there were times when the
corridors were empty for several days.
It is
notable that even though takt scheduling led to shortened construction time, the
other takt area was empty almost 50% of the time. A paint job that was a
specific week’s only scheduled task took just 50 minutes to complete. Despite
this, 20% attendance in the takt area was enough to keep the project on
schedule.
Unnecessary Movement
Another Aalto
student, NCC’s Anton Ruohomäki, shared data from the Vallila Folks Hotel
renovation site. He used surveys and video cameras to record the interior construction of
two adjacent hotel rooms. The takt time was one day, and the takt area around
20 square meters in size.
On average,
the rooms were empty for 63% of the workday, which is more than the 41% in the
original plan. There was, however, a great deal of movement when work was
taking place, but much of it unnecessary.
The events
of one particular day in one of the rooms demonstrate this fact. During this
day, eight different workers visited the room 62 times in total. One tile
installer stepped into the room 27 times, and another 26 times. Ten visits
lasted longer than five minutes. The average duration of visits under five
minutes was 39 seconds!
Disturbances and
Interruptions
Henri Ahoste, a graduate student from Skanska, followed
the installation of raised access floors and their underlying electrical
installations for three months at the Urban Environment House site in Helsinki.
The work took place in three takt areas, each covering an entire floor. Ahoste
measured and surveyed disturbances and interruptions in the process, which are
factors that cause process waste.
For example,
an absence of initial information led to delayed material deliveries. Sometimes
the planned workforce was not available. There were also conflicts with the
previous task due to a lack of coordination and communication.
“Location-based
scheduling in Finland is run-of-the-mill stuff, and we use Last Planner
Sessions quite often. Still, the level of scheduling and production planning on
construction sites seems to be fairly low,” Ahoste stated.
Collaborative Planning Is
the Way Forward
Other
studies corroborate Ahoste’s concern. Unclear schedules lead to time pressure,
create quality issues, and diminish worker well-being. They are typically the
result of a common top-down scheduling practice that has little to do with the
realities of construction sites. Collaborative production planning with the
Last Planner System (LPS), in contrast, brings rational scheduling practices to
the jobsite.
Subcontractors
on the Urban Environment House construction site were enthusiastic about
planning collaboratively with the LPS. They were able to keep track of the
schedule in daily meetings, which gave them a real-time situational picture of
the site. They also started to favor takt planning over conventional planning.
The condensed takt production schedule proved workable, even if some tasks were
not completed 100% as scheduled.
Ahoste
believes that future projects should use takt production and collaborative
planning. He recommends that a construction site should use a neutral
facilitator to run the LPS sessions. Having comprehensible visual guidelines
and requirements for LPS participants is also important. In order to maximize
the benefits of collaborative planning, it should cover design, production, and
procurement.
Based on the day’s presentations, takt production is a step forward, but it needs to be planned and monitored collaboratively when put into practice.
Read my full report of the Aalto workshop at building2030.com.
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