The Transbay Joint Powers Authority, after closing its recently dedicated Salesforce Transit Center, is investigating the cause of cracked built-up plate girders supporting the roof garden.

A diminutive bus station on Minnesota’s Highway 61, just southeast of St. Paul, is the first step in a much larger redevelopment project.

An old Chicago station serving 1.8 million subway and bus riders each year is soon to receive a $15 million makeover.

With a billowing, veil-like facade and generous skylights, a large new transportation hub in San Francisco will replace a shabby station from the 1930s.

Nearly 90 years after it was first proposed, a 2-mile stretch of subway connects Manhattan’s Upper East Side to Midtown.