Wilkinson Eyre Architects

The proposed new bridges occupy prime gateway locations and are informed by the sites' complex social, cultural and historical context. They will be highly visible on the daily commute and from within the parks and beaches that are a unique and distinct feature of Chicago. It is appropriate that in a program, which is aimed at reconnection and regeneration [particularly in the 'severed' neighborhoods of Near South Chicago], the bridges should provide a visually confident statement and an optimistic spirit through design. The proposal creates, in each case, a dual-acting landmark, experienced in isolation by the user, and in series by the commuter.

The five bridges are conceived as a design family, each individually identifiable signature structures, but legibly parts of a wider scheme. The concept allows for variations in the structural organization of the crossings, but applies a common strategy to the bridge approaches. The design of the crossings is most closely related where their setting is similar; hence the trio of bridges that span both highway and rail track at 35th, 41st and 43rd Streets display a high degree of commonality. These in turn are closely related to the highway 'only' crossing at North Avenue, whilst the Chicago River Moveable Bridge is a pragmatically conceived solution to a complex program and is consequently distinct.

The family-of-bridges proposal responds to the themes of 'identity' and 'experience', providing a common visual thread that allows the development to be understood as a single initiative, the impact of which is greater than the sum of its parts. By relating the bridges, a new and specific typology is created, a Chicago Lakefront bridge synonymous with, and derived from, its location.

The spiral bridge approach structures provide an emphatic scheme-wide design feature linking all five proposals with differing curved plan alignments characterizing the individual spans. All but the moveable bridge have a related structural arrangement. The City-to-Lakefront typology develops the standard scenario, and each design is derived from this condition and adapted to the varying sites.

The designs occur at intervals along Lake Shore Drive and it is this rhythmically repeated motif experienced by rail passengers and, more particularly, car users whose cumulative effect will be the strong visual connection of these bridges with the journey. The three or four bridges that would be encountered on a typical journey are variations on a theme that are subtly distinct to the commuter but highly individual to the bridge user, who would fully experience the individual curved alignment of the crossing in each case.

The Lake Shore Drive 'corridor' severs the city from its primary recreational amenity whilst providing effective containment of the lakeside environment, disassociating it physically and philosophically from the urban grid. Whilst the city is relieved by the intervention of parks and piazzas, the shore is uninterrupted by topographic or developed mass, providing the opportunity to create special features.

A key element in development of the proposals has been a response to the Lakefront landscape providing visual event as a counterpoint. The clearance requirements over the highway dictate significant ramped approaches and the abutments require mass at the bridge ends. The designs gather these functions into a sculptural assembly at each side of the span as a 'land art' piece, manipulating the landscape in which it is set. Each takes the form of a conic spiral, a tumulus-like earth mound formed by the furled-up ramps spiraling upwards to support the deck. The geometry is rooted in nature, a seminal form that is a familiar theme in land art [Smithson, Morris, etc]

As Lake Shore Drive cuts diagonally across the urban grid, it disconnects the city, halting the eastwards progress of streets to the shore. The reconnection of street alignments across the divide repairs the urban cut carrying the lakefront parkland back into the city. Crossing these bridges will be an act of transition, a leisure connection. The organic nature of the designs with their winding approaches and sinuous decks offer an experiential journey and create a 'portal' into the recreational environment.

In each case the approach cones and deck arrangements are oriented in response to the prevalent 'desire lines', picking up on the established layouts on each side and describing a fluid and seamless journey between them. The helical ramps are effective in gathering and delivering bridge users from/to their direction of travel, as well as accommodating the differing deck geometries, which spin off tangentially from the spiral at the appropriate angle. In every case the option of an in-line stair provides a direct and uninterrupted journey from side to side.

At each of the approach cones the spiralling geometry continues beyond its connection to the deck up to a viewing platform, and 'eyrie' from which the bridge, landscape and cityscape can be surveyed. On all but the moveable bridge, the geometry continues to rise around the platform with a spiralling cable-net that holds back the bridges' catenary support cable. Pedestrians can inhabit the dramatic captured volume within and engage with the structure as an integral component of the crossing experience. On the moveable bridge, no better vantage point will be available than these platforms to view the great drama of the bridge opening.