Blame it on the bad economy. Without the housing downturn, Siemens Transportation Systems wouldn’t have been able to buy 10 acres near its 13-acre plant in South Sacramento. Without the spike in gas prices, demand for light-rail cars might not have jumped in cities across North America. And if the U.S. dollar hadn’t sunk against the euro, the company wouldn’t have invested in transferring manufacturing from a factory in Austria to the Sacramento plant. The company is now in the middle of a $26 million expansion of its light-rail car assembly plant in Sacramento. It’s looking to fill 200 new jobs starting early next year. The plant began expanding in 2006 to meet $1 billion worth of orders in the pipeline. The company currently has a backlog of orders for seven cities.