"They're all saying they're short of skilled workers," he said.
Bryant said it took two to four years to train new staff and companies had relied heavily on foreign labour to fill their skill gaps.
"The problem is we haven't been training enough people to fill those roles."
Another of the authors, Fraser May, said the pressure on contracting companies was growing because councils and central government wanted them to do more work and faster.
"They want to get their work programmes filled and so they're asking contractors to basically up capacity to meet that, whether that's some of the major projects or whether its maintenance - water networks, roading networks, putting internet cables into the ground, everything like that - it all needs people and those people need skills to do the job."
May said the Ministry of Social Development and other agencies funded entry-level courses but they did not attract many people, and on-job training or apprenticeships were relatively new and small scale.
"It'd be much better if we had an entry point that people outside the industry could see. So if someone wanted to join the industry, say if you wanted to become an excavator operator or something along those lines, they could say 'oh right that's where I go' and be directed to go there.
"At the moment they can join a company and learn those skills. It would be great to prepare them a little more before they started doing that."
The Construction and Infrastructure Workforce Development Council is a new entity that sets qualifications for the industry and was created by the Government's overhaul of vocational education and training.
Its chief executive Philip Aldridge said training more workers was critical for the estimated $270 billion pipeline of new construction and infrastructure work.
"The civil infrastructure sector is struggling for labour like a lot of other sectors. So that may or can result in delayed works, things slowing down and the overall build programme not meeting expectations. So it's important we make sure there's a clear pipeline of workers coming through, there's clear pathways, and we meet all these big programmes that are coming up."
He said not enough training was happening.
"There's not enough and it's often a bit ad hoc and individual companies are doing their own thing to some extent, which is great, but they can be expanded and made more systematic and be clear about how they lead on to a career."
Connexis is the industry training organisation for civil construction and part of Te Pūkenga, the new national polytechnic and workplace training entity.
Its chief executive, Kaarin Gaukrodger, said part of the problem was that the sector didn't have a formal apprenticeship system until five years ago.
"Employers in the civil construction industry have lacked the formal trade training support that other industries have had from the tertiary education sector, which is part of the reason why they have had such a reluctance to take on new entrants and apprentices.
"Due to the infancy of civil apprenticeships, the other structures around pre-trade and entry-to-apprenticeship programmes are lacking and a lot of the contracting companies don't have the internal systems to support the new entrants that might not be work ready."
She said there was work under way to provide entry-level training through Te Pūkenga, and this year the ITO launched NCEA standards that gave school students an introduction to civil construction.
Gaukrodger said the ITO had more than 3500 trainees, nearly double the number before the pandemic, thanks to government programmes that subsidise employers to take on apprentices.
