Client: City of Fremont
Location: Fremont, CA
Completion Date: Ongoing
AVA was responsible for developing alternative concepts for a pedestrian crossing of Union Pacific Railroad lines running in the Niles area of the City of Fremont, California. This train stops required circuitous and lengthy pedestrian paths for passengers to cross tracks and access train loading platforms. Therefore, both an underground pedestrian tunnel crossing and a pedestrian bridge crossing were studied in detail, and various the concepts were assessed from a passenger safety and train operations point of view. All concepts were further evaluated from accessibility, engineering feasibility and constructability, and an aesthetic point of view.
These studies included overhead and underpass options. Several concepts were studied, including a flat truss structure, an arched tubular structure, suspension structure, a cantilevered structure, a cable-stayed bridge, etc., along with Rough Order of Magnitude (ROM) costs were added for each of the variations. A total of seven options were developed and a matrix of costs for each option was presented for comparison. The bridge concept was found to be the most advantageous even though a number of alternative concepts were entertained at the early stages.
An arch structured concept was selected as the best design and the most feasible alternative relative to aesthetics and the project economics point of view. The structure consists of two arched steel tubes that span from one side of the tracks to the other in a half circle shape. A very light bridge surface provides the walking structural element and is supported periodically from the arched tubes by thin steel rods. The only other element on the bridge are the guardrails, handrails and a light structure that is provided for the metal screens needed for added security of passengers crossing the tracks, and to prevent large objects from being tossed onto the tracks by vandals. Glass enclosed elevators and elevator shafts provide complete visibility and a feeling of safety and security for those using the elevators, since any unwanted activity in the elevators can be viewed from the outside with relative ease.