SULLIVAN SQUARE VIADUCT REHABILITATION
Boston, Massachusetts
C&C Consulting Engineers is under contract to the Boston Public Works Department to assist in replacement of the viaduct connecting Mystic Avenue and Broadway in Somerville to Rutherford Avenue in Charlestown. The structure, together with the associated Route 99 tunnel, was identified as structurally deficient during an inspection of various bridges in 1995.
After completing our original inspection, we worked with the City to devise a staged inspection, design and construction program to mitigate the deficiencies found in the field. In the first phase, leaking construction joints in the tunnel were treated and other improvements were made, allowing the tunnel to be re-opened for through traffic. The program was then directed to repairs/replacement of the viaduct. The goal of the City was to repair the viaduct sufficiently to be used for approximately ten more years until a more lasting traffic solution could be advanced through the environmental and public review process.
As a part of the planning and reconstruction of the viaduct, we prepared a Traffic Management Plan. Recognizing that there are over 44,000 vehicles using the viaduct daily, a great deal of emphasis was put on maintaining traffic flow on the existing structure, rather than shifting it to the surface street system during construction. The Plan called for reducing traffic to one lane in each direction and performing the remediation work alternately on the northbound and southbound sides of the viaduct. To allow construction under the viaduct, we called for diversion of surface street traffic through a city-owned parking lot during nighttime hours, when the lot would be otherwise empty.
Upon commencement of construction in the winter of 2001, it was found that portions of the viaduct have experienced accelerated deterioration due to lack of maintenance in recent years. The southbound portion of the viaduct has subsequently been closed and traffic has been diverted to the northbound side. At present, the Massachusetts Highway Department has directed that the entire viaduct be demolished, and administrators are considering alternative methods to provide for the traffic needs of the area.
