A warning that a stretched workforce could threaten the future of the country's infrastructure.  

Six billion dollars of projects including roads, schools and hospitals will kick off between now and late December.

Civil Contractors New Zealand Chief Executive Allan Pollard says 15-thousand construction workers have lost their jobs over the past year. 

He told Ryan Bridge the next six months will be achievable - but it could be a strain longer term. 

Pollard says we need to do some major scaling up of the work force over the next two years.