NORTH AVENUE DAM BRIDGE
MILWAUKEE, WI
Relationship to Surroundings: The design strategy begins with the existing conditions of the site and connections to the surrounding neighborhoods. In order to maximize the sense of connection, and create an exciting and practical insertion into the existing dam structure, the bridge is composed of three components that weave their way through the dam and over the water. Our strategy highlights the existing dam and site conditions, acting as a new layer of the landscape and allowing the user to quietly experience the history of the site without obliterating the past.
Design and Structural Concept: Inspired by the form of a fishing rod, the proposal incorporates three simple, elegant structural strategies for supporting the new walkway: The East Prow, the “Strung” Arc, and the West Landing.
To the east, the East Prow incorporates an ironwood boardwalk leading to the main span. The Prow is delicately supported, at a distance from the dam, on a latticework of steel and wood trusses attached to the south face of the existing dam structure. A closed wood and steel railing to the south defines the space of East Prow from views downstream, while open steel railings to the north and west allow for open views to the dam and the river opening respectively.
As it crosses the river, the Strung Arc ironwood walkway rests within a pair of arcing, tapered steel beams. The walkway is also subtly arched as it crosses the water, approximating but not exactly following the arc of the steel beams, giving a sense of coming upon a very special condition as one crosses the water. The railings at the Strung Arc are provided in part by open steel railings with wood handrails, and in part by the tapered steel beams themselves. The tapered steel beams are fixed at the east end, and rest on expansion rollers to the west. The thin steel construction is made structurally resilient by “stringing” the two ends together with a steel cable. This provides a camber to the beams and walkway, and pre-stresses the structure for reduced deflections when loaded.
After crossing the water, the walkway reaches the West Landing, which is embedded just north of the west section of dam spillway. At this end the walkway hovers slightly above the dam in order to connect with the existing topography at the entry easement and possible future river bike trail.