Seven bridges were replaced or significantly repaired, including one over Route 62 in Concord which was a late addition to the project. Thirteen grade crossings were replaced, nine interlockings built new or improved, and dispatching of some segments transferred from the outdated tower at Waltham to the MBTA's control center. A new freight crossover was added at Ayer, with the East Main Street bridge undercut to increase clearances.
