Dilworth Park is a vibrant portal to the region's multimodal transit system that highlights Philadelphia’s historic City Hall while offering a safe and comfortable public space in the heart of downtown Philadelphia.
A $55 million overhaul transformed Dilworth Plaza from an aging and uninviting 1970s-era square near Philadelphia’s City Hall into Dilworth Park, a public space and transit gateway. Center City District (CCD), a business improvement organization serving downtown Philadelphia, led the program, which provided green space, access for the disabled, improved connections to the region’s multimodal transit system, and other amenities that the former space lacked.
Urban managed the design of the renovations in coordination with CCD, SEPTA, and the City of Philadelphia. The plaza has been rebranded Dilworth Park and is helping restore City Hall — which is listed on the National Historic Register — as a downtown focal point and travel hub for commuters along with people visiting the Convention Center and nearby restaurants and hotels. We also provided civil, mechanical, electrical, and plumbing engineering design services along with an environmental investigation, scheduling, cost estimating, and constructability review. The design team included Kieran Timberlake Associates as lead architect, The Olin Studio for landscape architecture, and CVM Engineers for structural design.
The project was funded in part by a TIGER grant administered by the Federal Transit Administration, grants from the Commonwealth of Pennsylvania, funding from the City of Philadelphia, and private and institutional donations.
Dilworth Park involved multiple stakeholders with different needs that had to be addressed. The park is located next to the seat of civic government, and needed to conform to the purview of the Philadelphia Historic Commission and the Philadelphia Art Commission. SEPTA has an ongoing program to improve the stations that connect at Dilworth Park. CCD needed to develop a park that served the residents and businesses in the vicinity and could offer programming that would assist in funding the operations and maintenance of the park.
Structural design and maintaining access to public transit were some of the project’s challenges. We needed a design with a live load capacity that could be supported by the three levels of existing infrastructure underneath Dilworth Park. It also had to be constructed without closing SEPTA rail stations. More than 300,000 daily passengers use the subway, regional rail, and trolley lines that intersect at City Hall.
In addition, we had to work around the main electrical backbone for the Broad Street Subway. This backbone passed through the site and conflicted with a proposed fountain.
The park features a new interactive, programmable water feature with an integrated art component, café, lawn area, planting beds, and various event areas. Two new sloping glass pavilions shelter stairs while allowing daylight into the concourses below. They are much more user friendly and attractive than the old plaza’s entrances.
Two new elevators are part of the vertical transportation network that will make the four transit stations below the park accessible to disabled patrons for the first time. Walls and steps that were causing grade changes were removed to provide Americans with Disabilities Act-compliant access. The concourse was completely reconstructed as a well-lit room with clear lines of sight and improved signage to guide passengers to transit lines.
New HVAC and fire protection systems, designed by Urban, serve a cafe and concourse levels, and an air supply system produces the fog effect required for the art installation. We also designed plaza and concourse lighting, and power systems appropriate for various events.
We worked with the project team for SEPTA’s City Hall Station to establish a transfer between the two subways lines at the 15th Street and City Hall stations, under the park. Prior to renovations, transit patrons could only exit into the concourse.
Addressing site conditions, we reduced the plaza’s load (and avoided impacts to below-grade infrastructure) by replacing native materials with lightweight fill. Portions of the Broad Street Line’s duct bank were relocated to allow construction of the fountain.
Stormwater is collected, filtered, and re-used for irrigation. A series of trench drains conveys rainwater to a 15,000-gallon underground cistern, where it is stored for later use with landscaping or metered discharge to the storm sewer system. Trees added to the site help intercept the rainwater, reduce stormwater, and increase comfort for park users.
Construction was phased to allow the public continued use of the transit system — there was only one weekend service outage on the Market-Frankford subway line. During this outage, the roof of the subway tunnel was replaced with a thinner roof in order to create new transfer fare line. Rail services were replaced with a bus shuttle during the outage.
We completed an environmental investigation and prepared environmental clearance documents in accordance with the National Environmental Policy Act.
The contemporary park is paved with granite. Landscaped beds are surrounded by granite seat walls with seating areas within the landscaped beds on crushed stone. About 12,000 sf of granite from the original plaza was reused to create a feature wall in the concourse.
The fountain’s design encourages interaction form people in the park. It has over 240 jets located in six pixels. Each pixel can be operated independently and the jets within a pixel programmed for different effects.
During design, we considered a broad array of potential activities and programs for the park. The result is a flexible layout that can accommodate concerts, movie nights, wedding receptions, farmer’s markets, and even an ice rink during winter.
This high-profile modernization established a dynamic public space and safe and visible portal to Philadelphia’s multimodal transit system that has brought new life to one of the five city squares. CCD has a 30-year lease to maintain and manage Dilworth Park as a public space.