Crown agencies have spent more than $500,000 trying to uproot one of the country's oldest engineering firms from the path of the $1.75 billion Waterview motorway.

Transport Agency and Land Information NZ have spent the cash on professional costs trying to move Faulkner Collins' factory and offices from Stoddard Rd in Mt Roskill.

"Now you can see what we're up against," said Faulkner Collins managing director Hadley Wright. "But they won't pay our legal costs."

Years of negotiations came to a head 10 days ago when the agency and its lawyers arrived at the wire fabrication factory - where about 50 workers make products such as supermarket trolleys and fridge shelving - to evict the company and change the locks.

Faced with a convergence of Engineering, Printing and Manufacturing Union officials and advice that it could not commandeer the property without a court order, the agency retreated and offered to resume negotiations.

It has since said it has incurred additional professional costs of about $222,000 since last December, making a total of $538,000.

Mr Wright said the agencies had reimbursed about $50,000 of his legal costs, but were refusing to pay a further $80,000 in outstanding fees for a Queen's Counsel.

He also wants the Crown to pay about $1.38 million to move the factory to another site as well as rental and tax arrears of almost $1.5 million for which he says he has been unable to raise equity finance without the security of a relocation agreement.

He is upset that the Transport Agency wants him to pay over time a $300,000 "betterment liability" for an electrical system at the new site, saying his existing wiring is perfectly good for keeping his factory running.

The agency's new regional director, Stephen Town, said on Friday he was optimistic about reaching a settlement this week.