Mayor Kevin White outlined a development program that will dramatically expand the downtown shopping district by creating a new corridor of development running Park Plaza through Downtown Crossing to South Station. The $425 million project, which will include 2 million s/f of offices, has been formulated by the Boston Redevelopment Authority in conjunction with a consultant team headed by the Boston office of Skidmore, Owings & Merrill and funded by the Urban Mass. Transit Administration.