While it seems reports of construction projects running behind schedule are regularly in the news, the Pennsylvania Department of Transportation (PennDOT) recently completed a project one year ahead of schedule. The Bridges of 676 project included replacing seven bridge spans over route I-676, created green spaces and public friendly areas, and completed a number of street level enhancements.
The seven bridges, which are located between 18th and 22nd Streets and are within a half-mile of each other, are part of Philadelphia's busy Center City area. While the construction was sure to inconvenience commuters, it was essential. Craig Suhoskey, a Consultant Project Manager for AECOM and a former PennDOT employee, was responsible for the managing design effort. According to Suhoskey, “The seven bridges were from the late 1950s and had reached the end of their useful life.”
Replacing the Superstructures
The project involved replacing the superstructures in their entirety. Originally two-span adjacent prestressed concrete box beam structures, the replacement superstructures were one-span steel plate girder structures. The use of one-span structures over I-676 eliminated the need for extensive traffic control measures and additional construction staging that would have been required to repair the deteriorated center piers. Once the new superstructures were placed, the existing concrete center piers, which divide the eastbound and westbound lanes of I-676, were saw cut to the height of the median barrier; the one-span bridges now provide a more open, less confined feeling on I-676.
James Pezzotti, Associate Vice President, for Pennoni Associates, served as the design team project manager and lead bridge engineer on the project. Pezzotti said, “The abutments were tested and found to be in good condition so repairs were made. There was a chloride ion issue because over the years de-icing salts splashed on to the abutments causing both concrete and reinforcing steel deterioration.” The completion of an electrochemical chloride extraction process on the abutments during construction rectified the chloride ion contamination.
Compressing the Timeline
Originally designed to be done in two stages due to traffic concerns and impact, the project was compressed into one stage. Pezzotti notes PennDOT was able to do this since traffic was a less significant issue than the models estimated. Commuters found other ways to navigate the project site than the arranged detours.
Steve Laws, Senior Civil Engineer Supervisor for PennDOT, was responsible for general oversight over of the project. Laws notes the compression of the stages of projects allowed the team to start the bridges early and make accommodations to local traffic patterns. He also credits the design team for the early completion and for allowing the project to stay on budget. “The original design for the project was very good and comprehensive, and we were able to keep up with our staging,” said Laws.
PennDOT was very concerned about commuters and pedestrians and met with them many times through the design phase. To lessen the burden on them, PennDOT arranged with the contractor to do the demolition of the superstructures and for the beams to be moved at night. Suhoskey said, “Vine Expressway [name of I-676 in the area] was closed overnight from 11 p.m. to 5 a.m., when volume was light, to allow the contractor free reign to set up their equipment.” The contractor was obligated to move the equipment during the day.
Considerations for Pedestrians and Green Space
While consulting with the public and businesses, the design team learned of their concern regarding an intersection. The intersection, which is located in front of the popular Franklin Institute, covers nine lanes of traffic. Pedestrians would get trapped in the middle of the intersection. The islands where pedestrians could wait were small. With the construction, the size of the islands was increased.
In addition, a significant effort was made to reduce the length of the intersection. “An intersection was bent and relocated which enabled us to cut down the cross walk which helps pedestrians to cross at the intersection,” said Laws.
The adjustment of the intersection also addressed another safety issue. The Franklin Institute is a popular destination for school trips and busses are dropping kids off there regularly. A plaza was created outside the museum allowing visitors safe entry to the museum area.
Other aspects of the construction were its focus on green space enhancements. A void space by the 20th Street bridge was filled in and became a public green space measuring 250 by 100 feet. The space includes planters and landscaping, flowers, and a lawn area where people can sit. The main library in the city, which is right across the street from the new public space, has held events that utilized the space. The space has also been used by the city when events are held in the general vicinity.
The green enhancements aspect of the project included planting more than 10,000 plants, shrubs, and trees. Some of those different tree and plant types can be found on a pedestrian bridge. The bridge also includes a detailed arch, new benches, an oval grass park, flowers, and other landscaping.
Covering an open area at the west side of the park expanded a local park known as Shakespeare Park. Paver blocks were installed to create an amphitheater, which was landscaped with a variety of trees and shrubs. The Shakespeare statue was cleaned and refurbished and new park benches were installed. Another public space was landscaped and hardscaped. Trees, shrubs, and new benches were added and planter boxes line new sidewalks in the area.
Meeting PennDOT Standards
While making upgrades to the area, outside of the construction, PennDOT had certain requirements to follow. “The city of Philadelphia has developed standards of construction in the area. Some areas already meet these standards as they have undergone construction while others do not,” said Suhoskey. With PennDOT's recent work, they met the requirements that include granite curbs and highway lighting. Suhoskey sees it as a nice match that makes the area more attractive.
According to Laws, this sort of project – building bridges – is pretty straightforward. “At PennDOT, we're used to building bridges.” Accommodating pedestrians in the middle of a heavily trafficked area, while challenging, is also in PennDOT's wheelhouse. The challenge with the project came from the events beyond the everyday. “We were right in the middle of a number of major events including the Pope visit and Eagles Super Bowl parade,” said Laws. This, along, with being in the museum district made good planning even more important.
With the new bridges and green spaces, both commuters and pedestrians have benefitted. PennDOT's Bridges of 676 project is a win for the city of Philadelphia.
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