Bridge & Infrastructure Scanning in Alameda, CA

Alameda is an island, so every structure that matters here is a crossing. Alameda County operates four movable bridges to the mainland. The Park Street Bridge is a double-leaf bascule spanning 372 feet of the Oakland Estuary, opening roughly 1,700 times a year under about 40,000 vehicles a day. The Miller-Sweeney Bridge at Fruitvale Avenue is a steel stringer bascule, and beside it the Fruitvale railroad bridge is a vertical-lift Warren through truss, still operable although rail service across it ended in 2000. The High Street Bridge carries the third estuary crossing. To the south, the Bay Farm Island Bridge, formally the San Leandro Bay Bridge, is a single-leaf bascule completed in 1953, paralleled since 1995 by the Bay Farm Island Bicycle Bridge. Under the estuary, the Posey and Webster Street Tubes carry State Route 260 between the island and Oakland.

Movable bridges are the hardest structures to document from paper. Counterweight pits, trunnion assemblies, machinery decks, lock bars, live-load bearings, and the pier and fender geometry around them accumulate a century of repairs that never reached a drawing. A scan captures the whole assembly as measured geometry in a single visit, in the open and closed positions if the schedule allows, so a rehabilitation designer works from what is there. In the tubes, the same instrument returns a continuous clearance envelope along the bore, ventilation and utility encroachments included, without a crew standing in a traffic lane. Everything registers to a control network observed with GNSS and total station and adjusted by least squares with independent checks on NAD83 State Plane and NAVD88, which matters on ground this soft: filled shoreline, wharf structures, and levees around the island settle, and a baseline epoch is the only way to prove how much.

Deliverables are registered E57 or RCP clouds, clearance envelopes and diagrams, DWG or DXF sections, elevations, and machinery layouts, surface and mesh models, and epoch comparison exhibits. Local bridges advancing through the federal Highway Bridge Program and Caltrans Local Assistance carry documentation expectations we scope to. See infrastructure scanning, Alameda 3D scanning, and deformation monitoring.