A rendering of the finished Longfellow Bridge reconstruction.
After years of planning, design, careful attention to detours and the daunting feat of procuring the proper federal and state funding, work has begun on the reconstruction of the Longfellow Bridge, the critical vehicular commuter link connecting Cambridge to Boston over the famous Charles River.
According to the Massachusetts Department of Transportation (MassDOT), the $255 million Longfellow Bridge Rehabilitation Project will address the bridge’s current structural deficiencies, upgrade its structural capacity and bring it up to modern code, including improving multi-modal access and bridge street connections to meet accessibility guidelines.
A new American with Disabilities Act pedestrian bridge crossing adjacent to the heavily travelled Storrow Drive also will be constructed as part of this project.
The Longfellow remained one of the five most important, so-called “mega projects” for their scope and cost, prioritized by Gov. Deval L. Patrick, since he first assumed office six years ago. It has received funding, like the four other “megas,” through Patrick’s Accelerated Bridge Program, a multi-billion dollar earmark established to address and repair the dozens of decaying and aging commuter spans across the Commonwealth.
The other four mega projects in the design phase are the Burns Bridge in Worcester, John Greenleaf Whittier Bridge (Interstate 95) in Amesbury and Newburyport, the Fore River Bridge in Quincy and Weymouth, and the Spaghetti Ramps (Route 79/Interstate195) in Fall River.
Six Stages Over the Next Three Years
More than 28,000 vehicles cross the Longfellow Bridge daily, as they have for many decades. Its stone piers and abutments have endured the effects of the moving water of the Charles River and must be heavily bolstered.
In addition, there is the added critical dilemma of keeping the important MBTA Red Line subway train, which carries thousands of commuters to-and-from Cambridge and Boston, operating over the bridge daily during the three years of planned reconstruction.
Advertised by the Massachusetts Department of Transportation as a design-build project to save time and money, a construction team J.F. White Contracting Company in Stoughton/Framingham, Mass., Skanska USA Civil Northeast Inc. in East Elmhurst, N.Y., and Consigli Construction Co. in Milford/Boston, Mass., have formed a joint venture team referred to by MassDOT as White-Skanska-Consigli.
According to MassDOT Press Secretary, Sara Lavoie, the team is concurrently starting basic construction elements and has completed the overall design. They are completing the inspection of the existing support structures with Phase one of the intricate six stages of reconstruction set for spring of 2014.
The project is being completed in four construction phases, with six traffic stages. Lavoie directs curious traffic of a different kind, web traffic, to an eight-minute YouTube video animation, which dissects all six phases, showing how the task will be completed while subway trains weave around the work.
The video is posted on the project Web site at www.mass.gov/massdot/longfellowbridge.
Phase one will reconstruct the upstream (Boston bound) roadway and sidewalk. Phase two will reconstruct the inbound to Boston MBTA Red Line tracks. Phase three will reconstruct the outbound to Cambridge tracks and Phase four will reconstruct the downstream (Cambridge bound) roadway and sidewalk.
Outbound vehicular traffic to Cambridge is being detoured for the entire project duration. Traffic stage one is in place through September 2014 for reconstruction of the inbound to Boston road deck and sidewalk. During this stage one vehicle lane into Boston, a bicycle lane in each direction on the roadway and two-way pedestrian travel on the existing sidewalk are accommodated.
Traffic stage two will be implemented to install the temporary shoo-fly track for the outbound Red Line train on the outbound road deck. During this stage, pedestrians will continue to use the existing downstream sidewalk. One lane for vehicle travel to Boston and two-way bicycle travel will be accommodated on the new upstream roadway.
Traffic stage three shifts the Red Line trains to reconstruct the inbound track. One inbound lane for vehicles and one inbound bicycle lane will share the downstream roadway. Pedestrians will use the existing downstream sidewalk. Outbound bicycles will use the upstream side of the bridge.
During traffic stage four the Red Line trains move to reconstruct the outbound track. Pedestrians will continue to use the downstream sidewalk. One vehicle lane into Boston and two-way bicycle travel are accommodated on the upstream side of the bridge.
Traffic stage five shifts the Red Line trains onto the existing alignment to remove the inbound shoo-fly tracks. Two-way bicycle travel is accommodated on the upstream side of the bridge and one vehicle lane into Boston and two-way pedestrian travel are accommodated on the downstream side.
Traffic stage six provides two-way bicycle and pedestrian travel and one vehicle lane to Boston on the upstream side to reconstruct the downstream roadway and sidewalk.
“Currently, the first phase of the project is to demolish and reconstruct the upstream, Boston bound side of the bridge. The work will begin soon and continue through September 2014. Currently, the contractor is inspecting piers and installing scaffolding,” said Lavoie.
The project began with preliminary work in April and will be substantially complete in September 2016.
In order to to save money, MassDOT incorporated an incentive/disincentive clause into the bid specifications to ensure that the project is being completed on schedule.
“MassDOT’s contractor is required to maintain emergency response, MBTA Red Line service and bicycle and pedestrian access on the bridge at all times,” said Lavoie. “In order to ensure MBTA service in place, the current traffic management plan has a Cambridge-bound detour in place. The contractor will have one Boston-bound lane on the bridge at all times throughout the six phases of construction.”
The bridge will not be widened or lengthened to increase traffic flow.
“The bridge length will be unchanged. The width will also remain the same with the exception of a slight increase in width at the upstream Boston abutment, which will be shifted slightly to accommodate the new cross section that improves bicycle and pedestrian travel,” Lavoie said. “The final bridge configuration will safely accommodate all bridge users.
“In the final configuration, the upstream sidewalk will increase from 6 feet wide to 8 feet 6 inches. The downstream sidewalk will increase from 10 feet to 13 feet. The upstream side will have a 5-feet 6-inch bike lane and the downstream lane will be 6 feet wide,” said Lavoie.
Boston bound traffic volumes during both a.m. and p.m. peak periods are higher than Cambridge bound, according to Lavoie. There will be two Boston bound travel lanes, one Cambridge bound travel lane, bicycle lanes on each side of the bridge, and wider sidewalks on both sides.
A list of how much steel, concrete, asphalt, stone, etc. is not yet available, but special marine materials are known, due to reconstruction that will begin below the surface of the Charles River.
“There is some granite block cleaning in the ’splash zone’ being performed by divers operating a 5,000 psi pressure washer as part of the cleaning process in advance of the masonry joint repairs,” said Lavoie. “The joint repairs consist of deteriorated mortar removal and repair material is just ’Harris Construction Non-Shrink Cement Based Grout,’ injected by a progressive cavity pump into the joints.”
Lavoie said that despite the use of manlifts on floating barges in the river, there will be no significant contribution from a major crane company and no floating cranes.
STV Incorporated is the design-build entity’s designer. Jacobs Civil prepared the preliminary design and secured the necessary environmental permits. At least five sub-contractors and material suppliers are in place, but Lavoie said she could not release their names at this time, as they have not been officially approved by MassDOT.
Besides Accelerated Bridge Program techniques like the Incentive/Disincentive clause, and design/build contract, pre-cast elements to replace all decaying piers and supports have already been made. Environmental challenges have been carefully addressed.
“The Charles River is a valuable natural resource, and the bridge is located adjacent to the Esplanade in Boston and Memorial Drive in Cambridge where extensive public parkland exists,” said Lavoie. “The contractor has measures in place to protect water quality in the Charles River and to minimize impacts to parkland.”
All plaques and sculptures will be protected during construction and restored as part of the project.
The Devil Is in the Detours
The project will employ several detour routes for one of Boston’s most heavily traveled areas. The primary Cambridge bound detour uses Charles Street and Storrow Drive to reach Leverett Circle and cross the river via Monsignor O’Brien Highway (Route 28) to access Land Boulevard and First Street and Binney Street for Kendall Square and points west in Cambridge.
The alternate route uses Storrow Drive westbound to the Mass Avenue Bridge to reach Main Street via Vassar Street. On weekends, when MBTA buses will replace Red Line trains, Boston bound traffic will use Memorial Drive or Third Street and Binney Street to reach Land Boulevard and Leverett Circle.
According to Sara Lavoie, there are 25 weekends over the three and a half year-project when buses will replace Red Line trains to accommodate track work. On these weekends, only MBTA buses can use the bridge. All other vehicle traffic must use alternate routes. Bicyclists and pedestrians may continue to use the bridge in both directions, and access for emergency vehicles will be maintained.
All traffic detour maps are available on the project Web site at www.mass.gov/massdot/massdot/longfellowbridge.