Bridging the Gap


    Large-scale Infrastructure improvements, done properly, can incorporate both the functional and recreational

    By James Pezzotti and Jennifer Reigle

    Designing and constructing large-scale transportation projects in urban, multi-use environments can present unique challenges due to their multifaceted nature. Challenges vary from city-to-city, but many include managing high traffic volumes, limiting or eliminating disruptions to large events planned by the city and/or city stakeholders, the need to accommodate pedestrian and cyclist access and safety, site access, public and private utility coordination, and environmental and cultural resource clearances. These challenges may seem daunting; however, these projects are extremely important to cities, especially those looking to attract more foot traffic, pedestrian use, and smoother traffic conditions, and the result can be tremendously rewarding.

    View of the completed 20th Street Bridge, looking west. Photo: Kazi Hassan

    Pennoni encountered many of these challenges and several other complexities beyond those of a typical urban environment with our I-676 Vine Expressway Reconstruction project, which involved superstructure replacement of seven aging bridges, but we ultimately finished ahead of schedule while also increasing pedestrian safety and creating beautiful spaces for citizens and tourists to enjoy.

    I-676 is an integral part of Philadelphia’s traffic system and carries approximately 106,000 vehicles per day across its 1.75-mile length. The Pennsylvania Department of Transportation (PennDOT) District 6-0 retained Pennoni to lead with six design sub-consultants responsible for replacing seven structurally deficient superstructures over I-676 from 22nd Street to 18th Street. The project site was in a culturally-sensitive urban area, which provided the opportunity to improve pedestrian and vehicular traffic safety, increase access to local businesses, and enhance public spaces.

    The seven existing bridges consisted of five vehicular bridges and two pedestrian walkway bridges, all with substandard vertical clearance that required rectification during design. All the existing bridge superstructures, which were two-span, non-composite, prestressed concrete adjacent box beam structures varying in length from 96 feet to 135 feet, were replaced with single-span composite steel girder superstructures, which improved the vertical clearance over I-676. The existing center piers were removed, which increased visibility along the highway, and the existing reinforced concrete abutments were retrofitted and reused.

    Ensuring ongoing engagement and coordination with stakeholders and city representatives throughout the entirety of the project is one challenge that will arise. To successfully complete this project, coordination with over 40 stakeholders was crucial. The project stakeholders included local business associations, neighborhood groups, institutional neighbors and city departments including: The Parkway Council Foundation, Logan Square Neighborhood Association, The Franklin Institute, The Philadelphia Streets Department, and Parks and Recreation. Each project stakeholder was engaged during the entire design and construction process to ensure all concerns were heard, considered, and incorporated as needed and the needs of motorists, pedestrians, and cyclists were accounted for.

    View of the completed 21st Street Bridge. Photo: Joe Gidjunis

    Within this project boundaries and adjacent to the bridge construction are two large Civil War memorials and three sculptures: the Shakespeare sculpture, the General PennyPacker sculpture, and the Francisco DiMiranda sculpture. The city and other project stakeholders were concerned about the protection and preservation of these pieces during construction. To alleviate concerns, special provisions were included in the contract to build protective shelters around each memorial and sculpture, seismographs were installed to monitor construction vibrations, and the statues were cleaned and refurbished prior to the completion of the project.

    View of the completed Family Court Bridge, showcasing the increased public space and greenery. Photo: Kazi Hassan

    Accounting for large events around the project site, both planned and unplanned at the start of the design process, was another challenge. The planned events included the Democratic National Convention in July 2016, the NFL Draft in April 2017, the Parkway’s Centennial kickoff celebration in Fall 2017, annual Welcome America events, annual Made in America concerts, and the annual Philadelphia Marathon. In addition, an announcement was made that the city would host the World Meeting of Families and Papal visit in September 2015. At this point, the engineering plans and construction package for the project were nearly complete and required major revisions. The project was revised to be completed in two stages and multiple phases to accommodate this event. Major events are a regular occurrence in cities. It’s important to keep this in mind when developing the project plan and timeline. Breaking the project down in stages can help alleviate the extra challenges big events can bring on.

    Splitting the project into two stages helped solve another complexity. Traffic control was established to minimize disruptions for the high-volume of vehicular and pedestrian traffic. Stage 1 included 20th Street/Parkway/Free Library, 19th Street and Family Court bridges, while Stage 2 included 22nd Street, 21st Street, and 18th Street bridges. The 22nd Street, 21st Street and 20th Street/Parkway bridges remained partially open to vehicles and pedestrians during reconstruction while the remaining bridges were closed to traffic with detours posted.

    Expressway traffic control was a separate challenge. Based on the existing roadway configuration, only seven feet adjacent to the abutments was provided to the contractor for a long-term work zone. Short-term construction, such as removing or placing the bridge beams, was completed during overnight closures of I-676 from 11 p.m. to 5 a.m.; detours were determined to guide motorists around the construction during those closures. PennDOT provided construction updates, including road and bridge closures on the project website, and press releases so that it was easily accessible to motorists and pedestrians.

    View of 20th Street Bridge during construction. Photo: Kazi Hassan

    With pedestrians in mind, we implemented several safety improvements. The intersection of 20th Street and the Parkway were reconfigured to remove an existing leg of the intersection and an island was installed to allow for shorter pedestrian crossings across the Parkway and to reduce pedestrian/vehicular conflicts. Along the western edge of 20th Street, the crossing length for the Parkway was reduced by 54 percent. Traffic and pedestrian safety improved through the addition of 62 traffic signal posts and 67 traffic signal post pedestrian countdowns. Pedestrian refuge islands were redesigned at the Parkway at 20th Street and pedestrian bump-outs were added along Vine Street to assist with creating a shorter and safer pedestrian crossing. Access and visibility were improved with the addition of 87 ADA sidewalk ramps and 84 street lights.

    For projects in urban environments, incorporating elements beyond the functional ones are important to take into consideration. Increasing and enhancing public spaces with numerous beautification elements such as lawn areas, trees, raised planters, and benches, were designed and installed as part of this project. The area between the existing 20th Street/Parkway bridge and the Free Library bridge was capped to create an expanded Shakespeare Park. Additional green space was added to Pennypacker Park with the installation of a large grass oval in the middle of the bridge. These public parks are now used to host events, such as live entertainment, book signings, and cocktail events.

    The primary goal of the project, replacing the structurally deficient bridges, was accomplished along with the pedestrian safety improvements and beautification of the area which have not only made this area more attractive for the residents and tourists, thus increasing pedestrian traffic and use of the facilities nearby, but it has become integral for larger Parkway events, like annual festivals and even special events such as the Eagles Super Bowl Championship Parade in early 2018.

    Construction was completed a year ahead of schedule in the fall of 2018. This was possible because of the successful coordination between the owner, contracting team, and design team, as well as the technical expertise to replace the poor-condition superstructures, improve pedestrian and vehicular safety, and incorporate public green spaces, all while maintaining traffic during construction.

    James Pezzotti, PE, is an Associate Vice President, Project Manager/Senior Engineer at Pennoni in Philadelphia, PA. Jennifer Reigle, PE, is a Senior Engineer and Project Manager at Pennoni in Philadelphia, PA.