Ross Barney + Jankowski
[North Avenue] Architect: Ross Barney + Jankowski, Chicago Engineer: T.Y. Lin International, Chicago Consultants: Schuler & Shook, Chicago; Singh & Associates, Chicago
[Chicago River] Architect: Ross Barney + Jankowski, Chicago Engineer: T.Y. Lin International, Chicago Consultants: Harrington & Cortelyou, Kansas City, Missouri; American Surveying Consultants, Chicago; Geo Services, Naperville, Illinois; Jacobs/Ryan Associates, Chicago; Lang Associates, Wausau, Wisconsin; Schuler & Shook, Chicago; Singh & Associates, Chicago
 |
CHICAGO RIVER | NORTH AVENUE |
 |
 |
 |
Architect's Statement
THE CITY
The sweeping South Michigan Lakeshore has exactly
two interruptions: the Chicago River is the major one (the Calumet River
is the other). A crossing here symbolically ties the North Side of the
City to the South Side. Connecting DuSable Park to Burnham Harbor completes
the necklace of public lakeshore park that has become the birthright of
Chicagoans.
THE SITE
The Bridge is at the site of the City's birth, the confluence of Lake
Michigan and the Chicago River. This is where and how people came to this
place: Chicago. The bridge marks the site of the primal founding of Chicago.
It is important.
THE BRIDGE
Using the Trunnion and Bascule concepts long associated with the City,
its pedigree is pure Chicago. When it moves, transforming from a flat
line to an arc, the butterfly bridge is organic, spiritually linking to
the constant, pulsing growth of the City from this site.
THE EXPERIENCE
The link between parks is always visible, always tangible. In the open
position, the bridge deck and railing unfold, attempting (but failing)
to stay firmly anchored to the ground beneath them. But their function
has changed from static, utilitarian corridor to dynamic sculptural event.
In doing so, they enliven the lakefront experience, making it more than
simple connection.
SITE DESIGN
The north and south approaches to the bridge are raised on solitary piers
to minimize the visual impression in both parks. The south approach joins
to the existing ramp leading to Lake Shore Drive allowing for minimal
change to the park. The entire bridge is angled relative to the River
to allow an easy connection to the proposed Navy Pier flyover, further
minimizing the impact in DuSable Park.
Along these raised pathways, trees planted at-grade create the effect
of riding through the treetops; sheltering the rider from Lake Shore Drive
and creating a more intimate space while framing the view of the upcoming
bridge. The trees fall away and the view of the bridge and river opens
up in front of you.
BRIDGE DRIVE SYSTEM
The unique butterfly concept is composed of a combination bascule and
vertical-lift bridge. Movement of the bascule arch spans provides the
mechanism to raise the 250 ft. pedestrian bridge span as a vertical-lift
bridge.
The drive mechanism to move the arches consists of hydraulic cylinders
at each quadrant, near the arch springings. Arches will be counterweighted
to minimize the force needed to move the individual arches. Cylinders
are designed to move the balanced arch spans, raise the pedestrian lift
span and supporting cables, and overcome associated friction, rope bending
and related mechanical design loads. A mechanical locking system will
hold the bridge in the open and closed positions. Bumper blocks within
the pier provide a positive stop at the range of motion limits.
Trunnion bearings and roller bearing assemblies allow movement of the
arch span while accommodating associated arch loads at the base of the
arch. A positive connection between arch crowns serves to stabilize the
arch system for wind and live loading.
A hinged floor system on the pedestrian span accommodates geometric variations
as the lift cables raise the span. Spooled anchor cables maintain lateral
control of the moving span. In the closed position, a mechanical tensioning
system stabilizes the span for wind loading.
 |
 |
 |
Architect's Statement
THE CITY
Urbs in Horto, a city set in a garden. Quoted directly form Burnham's Plan of Chicago, Urbs in Horto creates a conceptual visualization for both the physical and mental image of the city of Chicago. A system of reclaimed parks links the north and south lakeshores, creating a natural relief from the crowded density of a future international metropolis. Of the people, for the people.
THE SITE
The Bridge is at North Avenue spanning Lake Shore Drive, linking Lincoln Park to the beaches and pedestrian paths that travel the lake north and south.
Burnham wrote in his visionary dialogue:
"The opportunities for large parks in the immediate vicinity of Chicago are ample. First in importance is the shore of Lake Michigan, which should be treated as park space to the greatest possible extent. The Lake front by right belongs to the people. It affords their one great unobstructed view, stretching away to the horizon, where water and clouds seem to meet. ... Wherever possible, the outer shore should be a beach by which the waves may break; and the slopes leading down to the water should be quiet stretches of green."
The site is this opportunity between the Beach and the Park.
THE BRIDGE
The bridge is a fixed span arch, paying homage to the existing clear span bridge that functions as a gateway to and from the city center. The uninterrupted stainless steel span is a sculpture in the park, springing lightly yet forcefully over the road, linked only by a system of tension cables to the deck below.
The deck is the truly spectacular piece of the bridge. It is not a patch of hard concrete between park and beach; it is vegetated. It IS park, a "quiet stretch of green" to be experienced by the people.
A single box beam reaches across the Drive, allowing for a view and experience untainted by structural density. The ground is stretched up and over Lake Shore Drive, a green space interlaced with routes for all speeds: biking, running, walking, standing, sitting, and resting.
THE EXPERIENCE
The experience of the bridge is additive, building upon the historical idea of park by the people of the city. The bridge by description is a new piece of sculpture at the scale of automobile within Lincoln Park, connecting a now severed relationship. The experience is slow, rising quietly out of the landscape on planted berms, reaching an apex off-center toward the lake reinforcing the vantage point of the horizon, never leaving the green of the park.
SITE DESIGN
The site design is one of historical context.
The shape of the deck aligns with existing paths and geography rising at a 1:20 slope, creating a seamless continuity with no beginning or end. Individual routes were created for the cyclists and pedestrians, recognizing the differences in the desired speeds of experience. The fast route follows the shape of the deck, speeding along the interior while the slower pedestrian and recreation/relaxation areas are focused toward the city and lake, taking advantage of the skyline for pauses and picture taking.
The landscape will build upon the indigenous plantings and trees that are currently present, with the edges being clad in ivy to complete the experience.
