NEW BEDFORD — The estimated $400 million replacement of the 1,350-foot-long, many-ramped “viaduct” bridge that carries Interstate 195 over Route 18 is a little like heart surgery on New Bedford.

The bridge carries traffic over I-99 at the Imler intersection in King Township, Bedford County. While Swank Construction Co. LLC of New Kensington is working on the project, northbound traffic ...