Bridge & Infrastructure Scanning in Sausalito, CA

Sausalito carries an unusual structure inventory for a small city. The Waldo Grade, the stretch of US-101 and State Route 1 between the Spencer Avenue offramp and Marin City, lies within the city limits and includes the twin bores of the Robin Williams Tunnel, the original Waldo Tunnel bore completed in 1937 and its companion in 1954, along with two sidehill viaducts north of the tunnels that span gullies and broken ground, plus the retaining and drainage structures that hold the alignment on the hillside. Below, the waterfront runs from the ferry terminal at Humboldt Avenue through the Marinship district, where World War II shipyard fill supports piers, bulkheads, seawalls, and the docks of the floating home community, and where Bridgeway is the single arterial threading all of it.

Those are exactly the assets a total station cannot document efficiently and a scanner can. 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 against monuments held out of the adjustment. Inside a tunnel, where satellite positioning is unavailable, control is traversed in from the portals so the bore lands on real coordinates: the deliverable is a lining surface, clearance envelope computed around the actual travelled way, ovality and convergence sections, and any encroachment on the design envelope. On the viaducts and walls it is deck, soffit, bent, abutment, bearing, and joint geometry for retrofit or rehabilitation.

Fill settles and hillsides creep, so baselines matter here. Registered to stable control, a later epoch reports movement of a wall, a bulkhead, a pier, or a tunnel lining as a measured difference rather than an opinion. Deliverables are E57 or RCP point clouds, DWG/DXF plans, sections, and clearance exhibits, and BIM-ready models. See infrastructure scanning, 3D scanning in Sausalito, and deformation monitoring.