The Balance Bridge, proposed as a pedestrian span for the Puddefjorden in Bergen, Norway, exemplifies SOM’s historic commitment to the fusion of architectural design with advanced engineering. The 132-meter-long Balance Bridge is at once a soaring, emblematic gateway to Bergen and a technologically advanced, zero-energy structure. Gracefully poised both open and closed, the bridge relies on photovoltaic cells to power the hydraulic system that raises and lowers the cantilevered spans, eliminating the need for a polluting engine or any structural supports sunk into the channel.
The unique hydraulic system consists of a pump that moves water back and forth between two internal chambers. These are located in line with the bridge within the counterbalance sections of the cantilevered spans. When boat traffic requires it, water is moved from the forward chamber to the rear, which alters the balance of the bridge enough to enable gravity to move the bridge without the use of hydraulic actuators or powered drive mechanisms. Solar cells mounted on top of the water chambers generate energy to power the pumps and makes the bridge electromechanically self-sufficient.
The materials used for the bridge and its pumping system are designed to be economical, durable, handsome, and low-maintenance. The galvanized steel structure combined with high-strength steel suspension cables is both efficient and lightweight. The proposed walking surface is a stainless steel grating filled with porous ceramic material enabling drainage. The stainless steel grating is left exposed on the span’s bicycle path to further facilitate drainage and differentiate between uses. The reinforced acrylic water-tanks in the bridge’s counterweight sections are supported by a perforated steel structure, allowing the movement of the water to be visible to observers.
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