Bridge & Infrastructure Scanning in Petaluma, CA

Few cities this size own a movable bridge, and Petaluma owns a notable one. The D Street bridge, a 1933 single-leaf highway bascule designed by the San Francisco engineer Leon H. Nishkian, still lifts over the Petaluma River and still closes to traffic when the river is dredged. Upstream, the Washington Street crossing replaced a 1918 Strauss double-leaf trunnion bascule with a concrete structure finished in 1970. South of downtown, SMART operates the Haystack Landing bascule railroad bridge over the river, built in 1987 and normally kept in the open position with a tender monitoring marine channels. US-101 crosses the river as well, on a corridor whose Marin-Sonoma Narrows widening ran south from De Long Avenue toward Novato. Around all of it lies the working turning basin and a broad mapped floodplain.

Movable spans are the hardest case for conventional survey and the best case for scanning, because their geometry only means something in a stated position. We set and observe a control network on NGS and CSRC published stations, work in NAD83 State Plane and NAVD88, adjust by least squares, and check independently, then scan the span in the positions that matter: closed for roadway and clearance geometry, open for channel clearance and machinery envelope. The registered cloud carries leaf and trunnion geometry, deck and soffit surfaces, counterweight and pit dimensions, live-load and rest-strip bearing locations, joint openings, and abutment and pier faces.

Fixed structures get the same treatment: clearance computed across the full travelled way, structural as-builts for retrofit, rehabilitation, or load rating, and channel cross sections for hydraulic review. Baseline epochs registered to stable control let later scans measure scour, settlement, and misalignment. City bridges advancing through the federal Highway Bridge Program and Caltrans Local Assistance need that documented control. Deliverables are E57 or RCP point clouds, DWG/DXF plans, sections, and clearance exhibits, and BIM-ready models. See infrastructure scanning, 3D scanning in Petaluma, and deformation monitoring.