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|Federal Highway Administration > Publications > Public Roads > Vol. 68 · No. 2 > The Space Between|
The Space Between
by Dana Alexander Nolfe
An innovative infill project helped the Rhode Island DOT replace an aging bridge while preserving part of the original structure as a bike and pedestrian route.
When planned repairs to a crucial bridge in Providence, RI, revealed the need to replace the aging structure, the Rhode Island Department of Transportation (RIDOT) faced a complex challenge–the heavily traveled bridge is historically important and hemmed in by existing communities.
Washington Bridge 200 connects Rhode Island to Cape Cod and other parts of Massachusetts. The busy Interstate 195 (I–195) thoroughfare carries 90,000 cars per day eastbound over the Seekonk River. Westbound traffic crosses the river on an adjacent structure, Washington Bridge 700.
Built in 1930, Washington Bridge 200 is one of only three large, open-spandrel bridges in Rhode Island. When RIDOT began planning repairs, previous experience rehabilitating one of the other open-spandrel bridges–the Ashton Viaduct Bridge 275–prompted the department to conduct a thorough investigation of the condition of the concrete. "The lessons we learned at the Ashton Viaduct, where reconstruction was completed in 2000, showed us how to proceed on the Washington Bridge," says RIDOT Director James R. Capaldi, P.E., who was chief engineer on the Ashton Viaduct work.
Although preconstruction testing on Ashton Viaduct indicated that the concrete was reasonably sound, the extent of the necessary repairs greatly exceeded the engineers' original expectations, and the bridge ultimately needed to close for major repairs.
"Once we got into Washington Bridge, we realized we should do additional tests," says RIDOT Chief Engineer Edmund T. Parker, Jr., P.E. "Early in the process we understood that the concrete was not what we expected it to be." Upon close investigation, RIDOT inspectors discovered that the Washington Bridge was plagued with a patchwork of good and bad concrete intermingled. What should have been a repair job was turning into a much larger replacement project.
Adding to the challenge, the historic bridge is located in an area where the right-of-way acquisitions necessary to build a new structure would be costly. And the project needed to be timed carefully to open in the summer of 2008, when a new 1.6-kilometer (1-mile) segment of the I–195 Relocation Project will open and connect to the Washington Bridge.
The solution? RIDOT developed a plan to build a new five-lane bridge that fits snuggly within the 13.7-meter (45-foot) gap between the existing east and westbound structures. A win-win solution, the project would not affect daily traffic or encroach on the rights-of-way of neighboring communities–and it would preserve part of the historic bridge as a scenic bicycle and pedestrian route. Here is how RIDOT did it.
A Decorated History
More than 70 years old, Washington Bridge 200 is considered to be Rhode Island's premiere historic bridge. The current structure replaced an outmoded steel-truss swing-span bridge built in 1885, which carried a streetcar line on an 8.2-meter (27-foot)-wide roadway.
When former Rhode Island Governor Norman S. Case formally inspected and opened Washington Bridge on September 25, 1930, the bridge provided the first direct highway connection between Rhode Island's two leading cities, Providence and Newport. The structure exemplified the City Beautiful movement of the late 19th and early 20th centuries and the Classical Revival style of architecture.
In November 1930, the American Society of Civil Engineers' Civil Engineering magazine said the Washington Bridge was "a product of a combination of the highest type of engineering and architectural skill, and will long stand as an object of utility and beauty of which the people of Rhode Island may well be proud."
The open-spandrel, reinforced concrete arch bridge was a popular style for early 20th century multiple-span highways bridges. The Washington Bridge stretched 549 meters (1,800 feet) in length, and at 25.9 meters (85 feet) in width, the bridge was exceptionally wide for its time. Rather than a massive, concrete-filled structure or solid spandrel walls, the bridge incorporated 6 separate arch ribs, 12 arch spans, and 1,512 vertical columns supporting the roadway deck. At the time, this method was more cost effective because it used less concrete and took advantage of local labor and materials.
In 1968, the State built Washington Bridge 700 directly north of Washington Bridge 200 to carry westbound traffic. Viewed from the side, the newer bridge echoes its elder's classic arched design and will remain unaffected by the work, as it was rehabilitated from 1995 to 1997. Preserving the historic shape and character of the eastbound bridge, therefore, were important goals in the replacement project.
Exploring the Options
After 2 years of intensive maintenance to keep Washington Bridge 200 in service, work began in earnest in 2003 to start the replacement process for the eastbound span. RIDOT anticipated that the rehabilitation would cost $15 to $20 million but ended up facing an $80- to $100-million project.
Building a new bridge south of the existing one would have created a costly right-of-way nightmare. Acquiring the right-of-way from a hotel on the west approach in Providence, for example, would have cost an estimated $40 to $50 million, and an entire neighborhood on the east approach in East Providence would have put the price out of the ballpark.
Closing the bridge for construction was not an option. "Too many people depend on it to get to work every day," Capaldi says. "Closing it would paralyze our State."
RIDOT needed to devise an alternative strategy. "All of a sudden, we had all these problems with the needs of replacing the bridge: the interstate, traffic, [and] historic issues," says RIDOT Design Project Manager Robert J. Pavia, P.E. "There was no room. Where do you go"left or right to replace the bridge? Then a solution resolved all those questions and turned adversity into opportunity."
With nowhere else to go, the gap between the two bridges became the focus of the design solution. RIDOT decided to build the new eastbound Washington Bridge within the 13.7 meter (45-foot) gap between the two existing structures. As the new bridge is installed adjacent to the Bridge 700, portions of the old Bridge 200 will be removed–all while maintaining four lanes of traffic in the eastbound direction.
"We had to look at an option that allowed us to build a new bridge while maintaining the existing travel lanes," says Richard G. Fondi, RIDOT administrator of the construction management group. "We could narrow them down and shift them, but we couldn't close them. The engineering decision was to start between the bridges and expand from there."
Down the Middle
By working construction from north to south, RIDOT planned to disassemble the bridge in phases. Each of the bridge's arch rings will be removed individually. Four 3.58-meter (11.75-foot) travel lanes temporarily will shift to the south side of the bridge. Prior to construction, the lanes were the standard 3.66-meter (12-foot) width.
RIDOT then will demolish one arch ring–4.57 meters (15 feet) of the bridge width–making the gap grow between the two bridges to 19.8 meters (65 feet), allowing the next phase of construction to occur. Two-thirds of the new bridge will be built in this gap. Another 9.1 meters (30 feet) of the old bridge then will be demolished, and the new bridge completed.
"RIDOT plans to demolish the northernmost arch ring–for the full length of the bridge first," says Pavia, whose job is to keep the project moving between engineering and construction. "Bracing will be installed between the piers, with tiebacks put on the arches. We will then sawcut the concrete deck between the two adjacent rings, structurally isolating the northernmost arch ring. Demolition of the concrete deck and columns can then occur, followed by the arch keystone. Finally the cantilevered portions and tiebacks can be removed."
According to Providence Managing Director of Transportation Paul M. Jordan, P.E., of design consultant Vanasse Hangen Brustlin, Inc., "One of the challenges of the design was that the new structure will rest partially on an existing concrete footing–timber pile foundation, as well as partially on new drilled shafts. [We] ensured that the existing timber piles would not be overstressed under static or seismic loads through flexible design of new drilled shafts and the use of isolation bearings."
A new pier bent with a spread footing will be constructed on the existing piers at the spring line of the arches and on the newly drilled shafts.
The first phase of this construction is building one column on a drilled shaft and a partial footing and one column on an existing foundation, followed by construction of a partial pier. Then the contractor will erect the steel superstructure, pour the concrete deck, and shift four lanes of traffic from the south side of the old bridge to the north portion of the new bridge. In the second phase, the contractor will complete the pier bent on an existing foundation using one more column, thus completing the superstructure of the new bridge.
"As a result of this work plan, we have had almost no traffic impacts," says Kazem Farhoumand, RIDOT's chief design engineer. "Most people who travel this bridge don't see any backups or any tieups as a result of our construction thus far."
A Park Like No Other
To save time, reduce costs, protect the environment, and preserve a portion of the historically significant bridge, RIDOT maintained a goal throughout the design process to reuse as much of the original structure as possible. Preserving part of the old bridge as a bicycle and pedestrian path was a key element in this strategy.
"The actual bike path that we had on the old bridge was narrow and really not functional other than for just a bike or two going by at a time," says Fondi. "The idea then developed to retain the southern two arch rings, thus preserving the southern stone facade of the Washington Bridge and building a park. It just seemed better to preserve [what] we had and save money at the same time."
The linearly shaped park will be a separate and distinct structure spanning the Seekonk River, accessible to pedestrians and bicyclists. The new park will feature a 3.4-meter (11-foot)-wide bike lane and a 2.1-meter (7-foot)-wide pedestrian path. By contrast, the previous bike path sat directly adjacent to traffic and was only 1.2 meters (4 feet) wide.
The pedestrian path will be placed waterside, while the bike lane will be closer to the new vehicular bridge, but built at a slightly higher grade than the pedestrian path to offer cyclists a clear view to the water. The bicycle path will run from India Point Park in Providence, over the Washington Bridge into East Providence, and continue 22.5 kilometers (14 miles) along the East Bay Bike Path to Barrington and Bristol.
In addition, the park will boast a 10.7-meter (35-foot)-wide overlook in the center of the span, from which visitors can admire the skyline of Providence, the residential tree-lined city of East Providence, and the sparkling upper Narragansett Bay and Seekonk River. The overlook and pedestrian walkway will feature benches, period lighting, landscaping, and rest areas.
In the January 25, 2002, edition of The Providence Journal, Ted Sanderson, executive director for the Rhode Island Historical Preservation & Heritage Commission, applauded RIDOT for its efforts. "[RIDOT] has come up with an amazing project to build the needed traffic lanes while saving a historic bridge and creating a new park," he said. "This may be unique in the Nation."
RIDOT Director Capaldi described the value of preserving part of the old bridge in the design: "This was a tremendous solution to our problem," he says. "We are talking about saving millions of dollars by saving the historic south facade. The two main piers and the one-time drawbridge operator's house are still in excellent condition, and it would have been a shame to take them down and dispose of them. We can now preserve all of this and incorporate these elements into the design."
Phasing Is Key
After conversations with contractors, RIDOT officials determined that it would be difficult, if not impossible, to secure bonding for a project with an estimated construction duration of 7 to 8 years. Therefore, Farhoumand says, "we decided we would phase the construction of the bridge. RIDOT would do the vehicular portion of the bridge first, and then in about 4 years, we are going to advertise the next phase of the project–the park phase."
When construction of the park begins, the south fascia wall of what had been part of the Washington Bridge roadway will be stabilized first. The existing concrete deck, sidewalk, and the columns standing on the arches will be removed, while the operator's house and the entire southern wall are retained. New hammerhead piers will be built on the existing piers, and a new superstructure of weathering steel and a concrete deck will be put into place. Steel will span over the remaining fiber-wrapped arches and be supported by hammerhead piers. The only thing the arches will then have to support will be their own weight.
"The north fascia wall will be constructed of a prefabricated, glass-reinforced concrete panel," Pavia says. "It will match the historic southern fascia stonework using form liners." The final phase of construction will include installing the architectural details, some of which will reuse stone and concrete elements from the original bridge.
A Winning Project
"This is one of the most complex projects RIDOT has ever undertaken," says RIDOT Director Capaldi. "What we are doing is essentially working on one bridge, but because of the phasing and the park, we are actually taking three bridges down and putting three back up."
The new five-lane Washington Bridge promises to improve traffic flow in the area, and the use of weathering steel and as few joints as possible will help make emergency maintenance a thing of the past.
In the end, the design compromise helped avoid the high cost of purchasing rights-of-way and achieved department goals for historic preservation–saving taxpayers more than $35 million in construction costs. Most of the construction will take place off the roadway, reducing delays for motorists. A portion of a historic bridge will remain intact, and the public will gain a new park. In addition, waterways will remain undisturbed because the old foundations will not be removed.
"In keeping with the department's policy of context-sensitive solutions, the overall design of the facility will honor the era of craftsman bridge building," says Wilfrid L. Gates, Jr., chairman of Gates, Leighton & Associates, Inc., the landscape architectural consulting firm working on the project. "The preservation of the historic south facade, the selection of materials, and the onsite interpretation of its history will define and signify RIDOT's enlightened transportation planning for the 21st century."
Dana Alexander Nolfe has been the chief public affairs officer for RIDOT since 1997. She oversees all aspects of RIDOT's public relations activities including special events, media relations, media campaigns, news releases, and speech writing. Nolfe also serves as an adjunct professor at Bryant University in Smithfield, RI, where she teaches both graduate and undergraduate courses in communications. Nolfe's professional experience includes other teaching positions and work for various television stations, including production work for programs such as ABC's 20/20 and World News Tonight. Nolfe holds a bachelor of arts degree in communications and political science from Queens College in Flushing, NY, and a master of arts degree in broadcast news journalism from New York University in New York City.
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