Study IDs trouble areas, aims to speed up construction projects

September 5, 2013 by Matt Shipman
Even small time buffers can lead to thousands of hours of delays on construction projects. Credit: North Carolina State University

Research from North Carolina State University identified factors that cause construction site managers to schedule more time than necessary for specific tasks. Understanding these factors and whether they can be reduced or eliminated could help the industry complete construction projects more quickly.

At issue is a planning concept called a time buffer. A time buffer is the difference between how long it should take to accomplish a task based on optimum productivity, and how long you think it will take in the real world. On any job, things can go wrong; or broken equipment can delay completion of a task. To account for these unforeseen events, construction foremen add time buffers into their schedules.

For example, if the optimum time for a task is three days, and a foreman adds one day of buffer time, the foreman tells his supervisor and project manager that the task will take four days.

"This is important, because construction projects – like building a school or hospital – can consist of thousands of tasks," says Dr. Min Liu, an assistant professor of civil, construction and environmental engineering at NC State and senior author of a paper on the research. "If every site manager builds a small buffer into every task, it can come to thousands of hours.

"Time buffers are contingencies that are built in, in case something goes wrong – but there is something called student syndrome," Liu says. "Student syndrome says a student won't do his until the night before it is due. Similarly, if a foreman thinks a task will take three days, but allots four days to do the work, the work is more likely to take the full four days. It's similar to Parkinson's Law, which says that a task will fill the amount of time allotted to complete it.

"We did this study to better understand how people determine when to add time buffers, and the length of those time buffers," Liu says. "This helps us determine how much of a time buffer is actually necessary, and will help us find ways to minimize wasted time in ."

The researchers analyzed survey results of 180 construction industry professionals from across the United States. They found a number of factors that contribute to time buffers.

Some factors are frequent contributors to time buffers, but do not increase the time buffer by very much. An example of this is a desire to protect the reputation of the construction company. Some factors occur infrequently, but can significantly lengthen a time buffer. An example of this is a delay in getting a necessary permit. And some factors are both frequent and significant. For example, if the task is part of a complex project – like a laboratory facility – that complexity often leads to lengthy time buffers.

"Project managers can use the factors we've identified to prioritize their review of construction tasks and target issues related to time buffers," Liu says. "For example, managers can pay particular attention to factors that are most likely to result in lengthy time buffers in order to determine if those time buffers are necessary or can be reduced."

Explore further: Wider buffers are better

More information: The paper, "Application of Time Buffers to Construction Project Task Durations," is published online in the Journal of Construction Engineering and Management. ascelibrary.org/doi/abs/10.1061/%28ASCE%29CO.1943-7862.0000735

Related Stories

Wider buffers are better

July 30, 2007

Excess nitrogen caused by fertilizers, animal waste, leaf litter, sewer lines, and highways is responsible for contaminating groundwater. It can also cause human health risks when found in drinking water and oxygen depleted ...

New buffer resists pH change, even as temperature drops

January 14, 2008

Researchers at the University of Illinois have found a simple solution to a problem that has plagued scientists for decades: the tendency of chemical buffers used to maintain the pH of laboratory samples to lose their efficacy ...

A review of vegetated buffer efficacy

February 16, 2010

Agricultural nonpoint source pollution has been listed as one of the leading sources of pollution in rivers and water bodies throughout the world. Environmental regulators and scientists are making concerted efforts to reduce ...

How grass buffers keep agricultural herbicides at bay

April 26, 2010

Grass buffer strips are commonly used in crop production to reduce herbicide runoff. These practices are encouraged through incentives, regulations or laws, and are effective at lowering herbicide concentration in runoff. ...

Plant buffers can slow runoff of veterinary antibiotics

March 22, 2011

Field tests by University of Missouri scientists have backed up laboratory research indicating that buffer strips of grass and other plants can reduce the amount of herbicide and veterinary antibiotics in surface runoff from ...

Recommended for you

Sydney makes its mark with electronic paper traffic signs

July 28, 2015

Visionect, which is in the business of helping companies build electronic paper display products, announced that Sydney has launched e-paper traffic signs. The traffic signage integrates displays from US manufacturer E Ink ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

rowbyme
not rated yet Sep 05, 2013
This was obviously not written by anyone who has actually worked in the construction industry. Schedules are far too compressed these days, and foremen are not allowed to add their own buffers, the schedules are dictated to them. This is unfortunately a pile of rubbish.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.