Bridge & Infrastructure Scanning in Napa, CA

Napa has rebuilt its river crossings more thoroughly than most cities its size. The Napa River and Napa Creek flood protection project, running roughly from State Route 29 at the Butler Bridge north to Trancas Street plus about a mile of Napa Creek, replaced five road bridges, among them First Street, Third Street, Maxwell, and Soscol, along with two railroad bridges, and added pedestrian crossings, floodwalls, terraces, and dry bypass channels at the oxbows. The George F. Butler Memorial Bridge itself, the State Route 29 span built in 1977, is the largest structure in the county, and Soscol Junction where Route 221 meets it has long been a candidate for a flyover. Imola Avenue crosses the river at the south end of the project reach, and the county still owns historic stone arch bridges, including the 1908 five-span Trancas Street bridge over Milliken Creek listed on the National Register.

Structures that span a designed flood channel have to be documented on real elevations or the documentation is worthless. We establish and observe a control network on NGS and CSRC published stations, work in NAD83 State Plane and NAVD88, adjust by least squares, and check against monuments held out of the solution. Registered to that network, a scan yields low-chord and soffit elevations, clearance computed across the full opening rather than at a point, deck surfaces and cross slopes, bent, abutment, bearing and joint geometry, floodwall and terrace faces, and channel cross sections at any station.

Masonry arch structures are a separate case and the one where scanning is least replaceable: they are curved, out of plane, and non-contact by necessity, and a registered cloud records them as they stand. Baseline epochs on stable control let later scans quantify settlement, arch spread, or scour. Deliverables are E57 or RCP point clouds, DWG/DXF plans, sections, and clearance exhibits, and BIM-ready models; filings go through the Napa County Surveyor. See infrastructure scanning, 3D scanning in Napa, and deformation monitoring.