Architecture and design firm DXA studio was awarded Grand Prize for their design for an urban pathway in New York City. Submitted for Construction Magazine’s 2019 Design Challenge, the project would span 9th Avenue to connect the new Moynihan Train Hall to the High Line and Hudson Yards. The design was created to push the boundaries of contemporary steel construction and create a signature public pathway for New York.
The Midtown Viaduct employs forward-thinking approaches to form, fabrication, assembly, and urban solutions that mitigate/synthesize the complex forces of contemporary cities. The site suffers from adversarial infrastructures and is bordered by two New York icons representing a pending surge in pedestrian traffic: Moynihan Station, and the High Line terminating at Hudson Yards. This context serves as inspiration for the project. Like the historic structures it connects, it takes the form of interlaced steel plate work, reminiscent of the industrial High Line and the steel of the original Penn Station.
The result is a diaphanous lattice work. Its density allows it to be surfaced, clad or filled to accept programming and landscape. The system displays the forces at work and allows light to reach the spaces below. The hybrid structure expresses speed and movement along the path, providing dynamic spaces and crossing distances as wide as a Manhattan intersection. The bridge is bi-level, providing two means of passage that serve the destination-oriented commuter, as well as the urban explorer while increasing the structural performance for longer spans.
It provides two distinct but interwoven planes emerging from the streetscape. These trajectories create a structure able to connect fringes of underdeveloped neighborhoods with competing identities. The approach is of its time like Penn. Station and the High Line were at their own inceptions. This expressionist infrastructure is identifiable rather than a singular object. It is a sequence of encounters along a path. The structure’s rhythm conveys a lateral legibility and efficiency; turning a hostile pedestrian obstacle into a public asset.
The existing mash-up of transportation on site (the Lincoln Tunnel access, a Bus Station, and narrow/absent sidewalks) create a pedestrian barrier. To mitigate this the projects main thoroughfare capitalizes on the 45’ sidewalk along Moynihan Station and a 35’ median between 30th Street and the Bus Station to ramp up to clear traffic. Once joined, the network splits to tie into the plaza above the Lincoln Tunnel Access and the Spur creating a central plaza.
Along the pathways the structure peels away creating secondary bridges as fast track paths strategically routed to enable a commuter-friendly efficiency. The structure can house a variety of spaces and functions. The reduced touch down moments allow for ADA lift and stair access points to be added negating having to go longer distances to ramp entrances. New volumes and covered spaces allow for planting, washrooms, bike storage, bars, and cafes, at and below the main level. The topography created by the main intersection allows for the plaza to be bound by planted seating, a reflecting pond, and patios as well for lighting and landscaping. The idea of a freeform path allows for changes of direction and unexpected viewpoints in counterpoint to the NYC grid. Tie-ins at the Spur and the Dyer Elevated Plaza capitalize on already existing stair and lift access points minimizing the need for additional ones and increasing the functional access to the site as a maximized commuter infrastructure. This infrastructure goes beyond much needed connections to transform a disused area of the city into an activated, dynamic and social pedestrian amenity.
Analogous to airplane wings, steel transverse ring-ribs are shaped according to cross-sections of the pathway spaced every 10’, less at areas of transition. Longitudinal linear ribs span the transverse rings to create 10-foot modules which are connected to create the tubular skeleton of the pathway. The system’s efficiency comes from the depth of the tubes created by the shape of the pathway and the flexibility in the performance of the system.
The system acts as a unidirectional spanning system at the 9th Avenue bridge and at longer, linear elements of the bridges. At the plaza, it transitions to a bi-directional system that behaves like a concrete waffle slab. The depth and thickness of the ribs varies accordingly.
Column/touch-down locations are selected to minimize their number and maximize their effectiveness. At locations of termination (the ramp adjacent to Moynihan Station, the connection to the plaza above Dyer Ave, and the High Line Spur) the pathway cantilevers over a final column support to abut existing structures without needing to definitively connect.
The bridge at 9th Ave (the most extreme span and the focus of the structural analysis) takes advantage of the added depth created by the upper paths. This depth creates a very deep and efficient truss.
The ribs are cut using a water-jet technology. The ribs are split into sections and welded together. Longitudinal ribs, also cut from stock plate to match the shape of the pathway, span between the transverse ribs. Prefabrication of 30’-50’ long sections allows them to be shipped to the site and erected with minimal disruption.
Article courtesy of DXA Studio