UPDATE 4.30pm: The company charged with building the Toowoomba Second Range Crossing said Ostwald Bros' financial woes would not cause delays to the project.
Nexus Infrastructure had employed the Dalby-based civil construction firm, which was placed in administration this morning, to carry out works on the massive $1.6 billion bypass.
It is believed ongoing contractual disputes between the two companies over the TSRC were at least partially behind Ostwald Bros' situation.
But a spokeswoman for Nexus Infrastructure said the issues would not affect the company's ability to deliver the project on time.
"Nexus Infrastructure confirm they are aware that Ostwald Bros Group have appointed administrators," she said.
"This is not expected to impact on the delivery program for the Toowoomba Second Range Crossing (TSRC).
"All enquiries regarding Ostwald Bros should be directed to the administrator."
Rumours surrounded the project last week, including that sub-contractors left the worksite regarding a pay dispute.
UPDATE 12.30pm: The director of Ostwald Bros put his lavish house up for sale, less than two weeks before the company went into voluntary administration.
Managing director Brendan Ostwald placed his $2.1 million East Brisbane home on the market earlier this month.
The Darling Downs civil construction firm put the future of its 470 employees at risk this morning when it was placed in the hands of administrators PriceWaterhouseCoopers.
Ostwald Bros' facilities on Montague Rd in South Brisbane were also put up for lease August 17, just 18 months after the company sold the "creative office" to Sydney-based Ralaxis Pty Ltd for $17 million.
However, the office was still occupied as of today.
All Ostwald Bros worksites have been shut down for 48 hours as the administrators complete a thorough review of the business and its solvency, with a creditors meeting set for September 6.
EARLIER: A Darling Downs civil construction company has gone into voluntary administration, putting nearly 500 jobs at risk.
Dalby-based Ostwald Bros made the announcement this morning after it handed the reins to administrators PriceWaterhouseCoopers.
It is understood the decision was mainly based on the company's ongoing contractual disputes with Nexus Infrastructure and works on the Toowoomba Second Range Crossing, as well as Seymour Whyte and upgrades to the Pacific Hwy in northern NSW.
Managing director Brendan Ostwald said he was "deeply saddened" by the decision, which encompassed all the company's trading entities and operations.
"It is with deep regret we announce, we are placing Ostwald Bros Group and Ostwald Construction Materials into voluntary administration today," he said.
"Over the past 27 years the family-owned and operated company has been a major employer and contributor to regional Queensland.
"Despite our best efforts, more recently, the company has been affected by commercial issues on two major infrastructure projects which has impacted cashflow and forced this decision today.
"We are deeply saddened by this decision and are acutely aware the impact it will have on our loyal employees, their families and the local community."
PriceWaterhouseCoopers partners Derrick Vickers and Sam Marsden said the process meant all staff would be stood down from work for 48 hours while the administrators carried out a review of the business.
"We will work with all stakeholders to determine the current position of the company and explore every possibility to restructure it for the future," Mr Vickers said.
Rumours swirled for the past two weeks after Ostwald Bros stopped work on the Second Range Crossing and left the site of the Pacific Hwy works on Friday.
Mr Ostwald also put his lavish East Brisbane house on the market just days before the announcement.
The first meeting with creditors is due for September 6.