Project: Silver Line Phase III Project (Lessons-Learned No. 1)
Grantee: Massachusetts Bay Transportation Authority (BTA), Boston
Title: Combining/Sequencing Value Engineering Workshop with Scope, Schedule, and Cost Workshop
Phase(s): Preliminary Engineering
Date: November and December 2008
When completed, Silver Line Phase III will physically connect the Silver Line Phase I with the Silver Line Phase II forming the Silver Line Bus Rapid Transit (BRT) system. Silver Line Phase I, defined as the Washington Street Replacement Service, is BRT service between Dudley Square in Roxbury and Downtown Boston. Silver Line Phase II is also BRT service, consisting of a tunnel extending from South Station to the World Trade Center in the waterfront area, combined with service to and from Logan International Airport.
Silver Line Phase III will consist of a tunnel segment and surface bus-only lanes. The tunnel will run between the existing South Station and Boylston Station along an Essex Street and Boylston Street alignment. Beyond Boylston Station, an underground turnaround loop beneath the intersection of Boylston Street and Charles Street will provide for operational flexibility. The tunnel will continue from the turnaround loop along Charles Street South to a portal located within a revised Tremont Street layout, roughly between Jefferson Street and Church Street. Within the tunnel, direct connections will be provided to existing MBTA Green Line and Orange Line transit services at Boylston and Chinatown Stations, respectively. A power mode change will occur at the mouth of the transition ramp on Tremont Street before Marginal Road where the vehicle will switch between electric overhead catenary and its own power system. Outside the tunnel, the BRT vehicles will operate in contra-flow bus only lanes with traffic signal prioritization along Marginal Road and Herald Street between Tremont Street and the existing BRT lanes along Washington Street. The Silver Line Phase III will also provide signal priority for the BRT operations on surface streets.
Under the advisement and guidance of the FTA, two workshops were conducted sequentially at the conclusion of the Preliminary Engineering Phase (30%) of the Project.
The fist workshop was a Value Engineering (VE) Workshop conducted in November 2008 by a team of independent consultants under the leadership of the MBTA. The VE provided an organized effort to analyze the function of systems, equipment, facilities, procedures and supplies by a multi-disciplined group for the purpose of achieving the required function at the lowest total cost, according to the requirements of the FTA guidelines in analyzing the design and cost-effectiveness of federally funded projects.
The VE recommendations presented included issues regarding construction management, geology, tunneling, risk mitigation, civil engineering, bus operations, environmental, and stations. Some of the notable VE recommendations included such items as reduction in the final tunnel lining from 2 ft to 1 ft; single pass lining in stead of double pass; utilizing a center platform station configuration with a side by side tunnels - a “binocular” tunnel concept throughout.
In December, 2008, under continued leadership, guidance, and participation of FTA staff, the Scope, Schedule, and Capital Cost Workshop was conducted by the PMOC in cooperation with the MBTA and Consultant staff. The Scope, Schedule, and Capital Cost Workshop encompass the review process according the requirements of three FTA’s Oversight Procedures (OPs/PGs): OP-32C (Project Scope Review), PG-33 (Capital Cost Review), and PG-34 (Project Schedule Review). Several issues and action items were identified during the course of the Workshop to mitigate project risks and enhance the accuracy and reliability of the cost estimate. One of the issues raised at the Workshop was for the MBTA to review a potential alternate bid utilizing the Tunnel Boring Machine (TBM) methodology for the Charles Street Segment due to the challenging ground conditions on that portion of the alignment.
Recommendations from the two workshops provided a comprehensive framework for the MBTA to evaluate a series of viable alternatives to effectively reduce overall cost and project risks. These alternatives include a core-tunnel alternative without the Charles Street segment; tunnels with binocular configurations; and combining Chinatown and Boylston Stations into one station.
The MBTA has begun the process of reviewing alternative evaluations report and selecting an alternative. It is anticipated that the process will be concluded in April 2009.
It is estimated that the overall cost savings for the project would be from $200 to $600 million.
The program of utilizing the results from the Value Engineering (VE) Workshop and the Scope, Schedule, and Capital Cost Workshop can be applied to most major Transit Capital projects across the nation. It would provide a means to comprehensively explore viable alternatives in order to achieve the goal of reducing overall cost and project risks. The project can benefit by judiciously integrating the VE effort in conjunction with the Scope, Schedule, and Capital Cost Workshop into the overall project design development process.