Danish researchers find American site productivity has been declining for past 40 years

Researchers from Denmark’s Aarhus University have analysed 40 years of data to show that productivity on North American construction sites has been declining since the 1970s.

The study links industry statistics with the efficiency of work done on sites to show that contractors have extracted less and less value out of a work hour since 1972. They suggest the reason for this is that craft workers spend more and more time on non-value-adding work, which adds extra time to the working day but reduces efficiency.

The team calculate that if craft workers in North America spent an extra 36 seconds per hour on value-adding work, it would add $5.4bn a year to the GDP of the US and Canada.

The report notes that it is up to construction management, not builders, to streamline the work process.

Hasse Neve, a researcher at Aarhus University’s department of engineering, said: "Although there is a degree of uncertainty, this shows what a society could earn by simply spending one percentage point more time on value-adding work on construction sites. But the vast majority of sites can be optimised even more, thus the numbers could be huge.

"We have lots of tools and knowledge that can make construction processes far more efficient, so why not use them? Fundamentally, construction is about generating value. A good final product for the client and users, and an efficient process for contractors, so they can earn money."

The team analyses data for the US and Canada between 1972 and 2010 because this is the only area where enough work-sampling studies have been carried out.

The report, "Determining the Relationship between Direct Work and Construction Labor Productivity in North America: Four Decades of Insights", was published in The Journal of Construction Engineering and Management.

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