A Michigan company is mobilizing this week at Enterprise South industrial park to start building one of the key buildings for Volkswagen’s planned auto assembly plant.

“They’re moving some trailers in,” said Jill Bratina, Volkswagen Group of America’s corporate communications director, as Detroit-based Walbridge starts erecting the $30 million shell for the facility’s paint shop.

Equipment is arriving with plans to start excavating Wednesday as the company’s workers begin laying the foundation and putting up steel beams, she said.

The German automaker has expanded the original size of the paint shop to handle 1,000 cars per day when production starts, slated for early 2011.

Frank Fischer, the Chattanooga plant project’s chief executive, has said the $1 billion plant remains a high focus of top VW officials.

In addition to the paint shop, body and assembly shops are to take form this year, he said.

Also, a state-of-the-art training center is expected to get under way soon and be finished by fall.

Matt Kisber, commissioner of the state Department of Economic and Community Development, said a bill to authorize bonds to finance the training center is expected to be introduced in February.

He said the city’s Industrial Development Board is the preferred entity to hold legal title to the training center, with VW having an option to buy it.

“They may choose to let the IDB keep it,” Mr. Kisber said. “The state will work with VW in what they want the center to be. They’ll give us the scope.”

Mr. Kisber cited the cooperation among the parties, including the city of Chattanooga and Hamilton County.

“It’s a model of how a project is to be done,” he said.

The 1.9 million-square-foot plant is expected to employ about 2,000 people when it is fully operational.