Somerset Construction Co. of Bethesda named MIE Properties Inc. and First Industrial Realty Trust as its partners in developing 5.5 million square feet on 1,000 acres of raw land in eastern Baltimore County, the companies announced Monday.

The decision represents a major advancement for the upcoming office and industrial park called Baltimore Crossroads @95. Made possible by the nearly completed Maryland 43 extension, the massive development is expected to generate at least 10,000 new jobs.

The Baltimore Business Journal first reported in June that the A.V. Williams Trust, owner of the 1,000 acres of land, selected Somerset Construction Co. as its development partner.

At the time, Neil Greenberg, principal of Somerset, said his company was searching for development partners and expected to have a decision by fall.

The park will include 2.5 million square feet of flex, office space, 2.5 million of industrial/manufacturing space and 500,000 square feet of retail space.

Baltimore County Executive James T. Smith urged the roomful of commercial real estate brokers - on hand for the Monday announcement - to bring growing companies that will yield high-paying jobs.

"We did not invest $65 million to have a bunch of McDonald's,” Smith said.

The first phase of the $65 million Route 43 extension is expected to be open in late 2005 - allowing construction to begin at that time.

Gerard J. Wit, a vice president for MIE Properties, said his company will start construction on four buildings - even if tenants have not yet been secured.

Greenberg assured county officials and business leaders that the project -- which replaced ideas for an Asian theme park and a NASCAR track -- would be successful.

"The vision is what it should have been all along - job creation," Greenberg said.

The development partners along with the county are targeting pharmaceutical and information technology companies - along with bioscience users.

A total project cost was unknown on Monday.