Officials say about $25 million is for any unanticipated problems as workers cut through a section of the bridge, roll it north on a set of rails and then replace it with a temporary bypass leading back to the span. The bridge will be closed over Labor Day weekend to complete the work. Officials want to make sure the bridge is ready to be reopened after the holiday.
The other $25 million is for design changes and more steel, workers and equipment. The additional money would bring the project's total cost to more than $450 million.
The bypass is expected to carry traffic temporarily, as work on the new earthquake-safe eastern span is completed.