I-579 Cap 'Frankie Pace Park'

Creating a Vital Bike and Pedestrian Link to Downtown Jobs and Resources

The I-579 Cap project created a bridge over the interstate roadway and interchange ramps, providing a vital connection between the Hill District and downtown neighborhoods in Pittsburgh, reconnecting the communities separated by the original construction of the highway more than 60 years ago. This infrastructure works to heal past social injustice while incorporating local culture, art and sustainability. Transportation improvements include new bicycle and pedestrian paths, a path to the Steel Plaza subway station, a bus stop on Centre Avenue, and the potential for a future bus rapid transit system between downtown and Oakland. In addition, street access is at grade on all four sides. The interstate and city streets received additional improvements, and the drainage system was upgraded. This concept has great meaning locally and is being implemented in other major cities.
 

Construction

This was a high-profile project involving the construction of a ‘cap’ structure (bridge with a 225-ft x 275-ft deck) on top of the I-579 roadway and interchange ramps with a three-acre community park over the cap. Building this type of structure in a dense urban environment often involves constrained work sites. At the I-579 site, multi-span bridges and existing retaining walls bordered all four sides of the cap. Combined with heavy commuter and commercial traffic, there was limited space for equipment and workers. To address these constraints, Fay, S&B USA Construction (Fay) completed the work in 14 phases of traffic for demolition, substructure construction and superstructure construction work. The sequencing was designed to limit lane closures on I-579 and surrounding arteries, as well as to avoid damage to the retaining walls and other existing structures.

Activities included major bridge deck construction, rehabilitating existing structures and connecting adjacent structures. Fay built new abutments behind the existing retaining walls to accommodate the new bridge beams. Workers installed 232 drilled micropiles to support the abutments, which minimized disturbance to the existing walls.

The cap’s superstructure incorporated 126 precast, prestressed concrete box beams weighing 140,000 lbs each and with a maximum length of 121 ft. The superstructure was divided into three units to allow transverse post-tensioning of the beams and better match the span configurations of the adjacent structures. This superstructure is durable, economical and strong enough to support the park’s unique loading, including up to five ft of soil. The precast concrete beams also supported installation of lighting underneath to ensure driver visibility on I-579 below.

Workers poured an 8-in-thick, cast-in-place concrete deck containing two layers of reinforcement steel in each direction on the beams to achieve full load-sharing among the beams.

When planning the park above the cap, the design needed to accommodate a notable elevation change from one side to the other, requiring extra fill that could significantly increase the load on the cap. To address this challenge, the team buried geofoam blocks in the park’s deepest sections and covered them with soil. The blocks weigh less than 3 lbs per cubic foot yet support the load placed on them.

To prevent water and runoff from the park above from penetrating and damaging the concrete deck and beams below, multiple waterproof layers were used.

In finishing the park, workers installed drainage, 1,800 lf of curved architectural walls, 50,000 sf of reinforced architectural sidewalks, decorative signage, seating, lawns, and tree and rain garden plantings. To comply with the Americans with Disability Act, the significant grade change across the park uses walkway switchbacks into the tiered raingardens at the northwest corner.  

Community Impact: Moving Forward

The Hill District was a vibrant cultural center for Black residents that had easy pedestrian access to downtown until the urban renewal of the 1960s and a multilane roadway divided the two areas. The cap project aimed to reconnect the Hill District and Pittsburgh’s downtown by repairing the concrete divide that led to social and economic dislocation. Crosstown Boulevard, later I-579, separated the two neighborhoods with retaining walls and loud traffic. Even after the Civic Arena was demolished in 2011, parking lots kept the two neighborhoods apart.

This project works to heal past social injustice while incorporating local culture, art, and sustainability. To design the park, community sessions and design reviews were held to receive input from Hill District residents and stakeholders. From this input, six key themes were chosen for the park: water, green, destination, music, seating, and connection.

Art in the park incorporates these six themes with story walls depicting the lives of important Hill District community figures such as Martin Delany—an abolitionist, educator and journalist—and Frankie Pace—a community organizer and business owner. Signage around the park narrates the park’s story and shows off amenities and art. A music-themed outdoor classroom with a garden provides a space for learning. As a part of the stormwater management system, there is a water feature that benefits not only the sustainability of the project but the park visitors as well.
 

Safety First

While providing upgrades to the surrounding area, the cap project also improved safety for pedestrians and bicyclists. The sidewalk along the Webster Avenue Bridge was removed due to its poor condition, and the pedestrian crosswalk at Bigelow Boulevard and Chatham Street was upgraded. The paths in the park are fully ADA compliant and path lighting helps provide safety to park users. Benches/resting areas provide comfortable seating and add to the public amenities of the park, and a new path to the Steel Plaza subway station and a new bus stop on Centre Avenue were added to provide safer access to public transportation.
 

Sustainability: Making an Impact

Additional attention was invested into the park’s sustainability, which can be seen throughout the park’s three beautiful acres. The park’s lawns work to catch stormwater that runs off I-579 and can absorb six inches of rainwater. Trench drains work alongside runoff management to collect stormwater and direct it towards the six rain gardens in the northwestern area of the park. The rain garden and lawn allow the runoff to evaporate or be absorbed by plants or soil, which reduces the amount of stormwater runoff to the sewer system. Additionally, shade from the trees will diminish heat from the pavement and minimize the energy needed to cool nearby buildings. Including the new trees, over 4,000 plants currently grow in the park.

Bridge of Opportunity

After the Hill District was disconnected from downtown, the community lost a significant amount of its peak population. The remaining population experiences high unemployment compared to the regional average. More than half of residents rely on public transportation or walking to get to work. The cap project provides a safe path to reach downtown, opening up Hill District residents to more job opportunities and a reliable way to access them. This ties into two major measures for the project’s success: increasing access to jobs and developing the Hill District in a way that benefits its current residents.

Funding

The cap project received state, local, and private funding, as well as a land match. Of the $32 million total cost to build the park, $19 million of funding came from a federal grant from the Transportation Investment Generating Economic Recovery (TIGER) program. This money was awarded for the cap project’s part in reviving the Hill District’s economy. Additional funding was procured from an extensive list of sources, indicative of the broad support behind this project.

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