The economic downturn has brought to a halt many developments around the region and nation, but in White Marsh a three-story office building is under construction. It will mirror another one recently completed across the street. Two more are planned.

Nottingham Properties Inc. quietly broke ground on the new building last month, sticking to a pattern it has followed since it created the Baltimore County residential, retail and office enclave - boom or recession.

"There is some risk, but it's not unbearable risk with this building," said J. Joseph Credit, executive vice president and chief operating officer at Nottingham. "Will it lease before it's finished? I can't say. But we have tenants expanding."

The Towson real estate company is the master developer of White Marsh Town Center and has been gauging growth there for decades. Credit said White Marsh is about 95 percent leased, and it's time for another building.

The new offices are slated to open in the fall, and Credit believes there will be some businesses looking for space by then. At 75,000-square-feet, the building could accommodate the growth of companies already in White Marsh, he said. The first building in the four-building Corporate Place complex was leased entirely to Comcast Cable Communications Inc. before it opened.

Nottingham began developing the Town Center in the 1970s. Residences came first, then shopping centers. The remainder of the space is slated mostly for offices.

About 300 acres of the original 2,000 are left to develop - enough room for about 2.5 million to 3 million square feet of offices, said Charles E. McMahon, development director at Nottingham.

McMahon attributed the area's popularity with businesses to amenities such as free parking, combined with the convenience of restaurants and shopping within walking distance. Nottingham's new office complex is across the street from the Avenue.

Nottingham has worked with Baltimore County over the years in planning Town Center. White Marsh became one of two focus areas for growth in the county. The other is Owings Mills.

Much of the population growth since the mid-1980s has been in those areas, said Fronda J. Cohen, a spokeswoman for the county's Department of Economic Development. Office and retail developments have been following the people, she said.

Cohen said Nottingham has done a good job keeping the flow of office space coming, without overbuilding. The new complex gives the company and the county something to use to attract new business to the area, she said.

"One thing Nottingham has done well is read the market and time development over decades," Cohen said. "Sometimes it seems like it takes a crystal ball."

There are only a handful of other Class A, or top-of-the-line, office buildings in the region under construction without committed tenants.

Brokers report that leasing has been slow. Business executives have been waiting to move or expand until they have a better picture of the economy.

Corporate Office Properties Trust broke ground in September on a 120,000-square-foot building in National Business Park, near Baltimore-Washington International Airport. It is expected to be completed next summer.

At the time, Randall M. Griffin, president and chief operating officer, said the general economic climate was bad, but that the business park was nearly full. He said he expected demand for space from the defense community.

The region, in general, may not be faring as well as White Marsh and the airport vicinity.

Among Class A offices in the region, vacancy is about 12.5 percent, or 15.4 percent if space for sublet is added, according to CoStar Group, a real estate information provider.

The region does not have as much sublet space as other parts of the country, such as Northern Virginia, because Baltimore attracted fewer dot-com technology companies that have faced financial troubles and abandoned their offices.

In Baltimore County, the vacancy rate among Class A office buildings is 7.5 percent. That rises to about 9 percent with sublet space. But White Marsh's vacancy rate is only about 5 percent.

Developers generally wait until the vacancy dips to about 10 percent before adding more space to the market, especially when things are churning so slowly.

"We've been developing and delivering space as we need it," Nottingham's Credit said. "We want to make sure we have enough for our existing tenants."