DOWNTOWN LINK, Philadelphia
The design team envisioned active and passive walls that would help connect passengers to the streets above and direct them to their locations. Passive walls are simple white tile and active walls are a series of inter-changeable modules. The active walls include EXTECH’s custom-engineered and -fabricated glass block system that, in concert with the static white and color-changing lights, simulate movement and transparency. A minimal amount of exposed metal framing was specified for EXTECH’s system to maximize the glass surface area and blend with the concourse’s existing, mortared glass block walls.
“The glass block wall is the common thread throughout the concourse,” says Kevin Rockey, R.A., project leader with Sowinski Sullivan Architects. “Where possible, in later phases, we plan to retain the existing glass block walls and use them to our advantage by retaining and restoring them as cost effectively as possible. Where this was not possible or practical, the new system is being used.”
Behind EXTECH’s customized glass block grid system, programmable LEDs generate the desired appearance and control. This also is where the conduit that previously was exposed and mounted to the corridor ceilings was re-routed, housed and secured. Planning for future services, extra room remains in the space concealed by the active walls’ glass block.
The Southeastern Pennsylvania Transportation Authority’s (SEPTA’s) Engineering, Maintenance and Construction department required the glass block system to comply with impact-resistance, graffiti-resistance, vibration-resistance and maintenance requirements. In addition, the glass block wall sections would need to vary in size and placement with some spanning full corridors and others integrating between maps and signage.
Successfully achieving SEPTA’s and Sowinski Sullivan Architects’ numerous criteria, EXTECH’s engineers developed a 1 1/2-inch glass block, joggled-set, modular system arranged in vertical panels with a narrow aluminum frame along the top and bottom. Up to seven vertical panels, each at 7-feet tall by 8-inches wide, are interconnected within a wall section.
GLASS BLOCK WALL SYSTEM MANUFACTURER: Exterior Technologies Inc. (EXTECH)
During summer 2018, SEPTA completed the first phase of the Downtown Link, its Center City concourse improvement program to upgrade the underground pedestrian tunnel network.
The multi-phased, $59.65 million improvement program seeks to address some of Pennsylvania transit system’s most pressing needs in its vital Center City pedestrian concourse. During the program’s first phase, contractors made structural repairs, remediated leaks, replaced lighting fixtures and escalators, upgraded elevators, improved security and enhanced architectural components.
The Downtown Link connects six subway stations; two regional rail systems; and provides access to many businesses, offices, historical points of interest and other destinations. This public space comprises more than 500,000 square feet.
“Originally built in the early 1900s, renovations over the years resulted in a piecemeal mismatch of materials. Nothing is straight; there are no right angles,” Rockey says. “In addition to addressing the areas in need of the most repair, SEPTA saw this as an opportunity to re-image the concourse as a destination unto itself. It can be disorienting underground and you can lose track of your geographical place. Within the concourse, we created an episodic experience of events for the passengers and public as they moved through the paths and corridors. Because of its consistent size and appearance, the modular system layout also can be changed. It is an evolving, living installation and a successful project.”
Photos: CHARLES UNIATOWSKI PHOTOGRAPHY