Rope Access Experts Provide Up-Close Inspections on a Global Landmark

Since 2015, HDR has provided bridge inspection and repair services for the Golden Gate Bridge, Highway and Transportation District, helping to maintain one of the world’s most iconic structures.

Using industrialised rope access, our teams have performed an arm’s-length inspection of fracture critical elements across the entire bridge and performed the first close-up visual inspection of the bridge’s main suspension span towers.

The historic structure, visited by tourists from across the world, sees approximately 40 million vehicles per year. But more than a global landmark, the 85-year-old bridge is also an important part of the local community and economy, providing a vital link between San Francisco and Marin County as one of four toll bridges providing a direct link to the San Francisco peninsula.

Regular Bridge Inspections

To comply with federal requirements, the District performs regular bridge inspections of all its bridges on a multi-year cycle. During the inspection, all elements of the structures are investigated and their condition assessed. Fracture critical elements — steel bridge tension members that, if they fail, could lead to the partial or complete collapse of a structure — are given particularly close scrutiny and are incorporated into the fracture critical plan developed by the District for the Golden Gate Bridge.

Fracture Critical Bridge Inspections

HDR was selected to inspect  fracture critical elements on approach spans and other areas of the bridge that could not be accessed by in-house inspectors using the bridge’s maintenance traveller system and catwalks.

HDR inspectors who have worked on the bridge are all certified by the Society of Professional Rope Access Technicians, or SPRAT, and each have at least three years experience inspecting fracture critical bridges.

For the 2021 inspection cycle, our team was required to inspect the entire underside of the suspension spans using rope access because the District’s maintenance traveller is currently being replaced.  Our inspection work included:

• All 261 bridge floorbeams, requiring nearly 9 miles of traversing on rope
• The entire underside of the steel deck, 400,000 square feet
• Nearly 13,000 feet of stiffening trusses, requiring 514 vertical descents
• Over 4,000 deck support pedestals

Our global employee network allowed us to mobilise the experienced specialists needed to complete this undertaking in a timely fashion. A team of 8-12 inspectors and an equal number of rigging technicians worked for one week per month over the course of eight months to inspect the bridge in 2021.

Inspection of Suspension Span Towers

In 2018, the same team of experienced rope access inspectors and rigging technicians performed the first ever close-up visual inspection of the main suspension span towers, in less than nine days. That inspection involved walking up the 3-foot diameter main cable to reach the top of the tower, then descending 500 feet from the top to the bridge sidewalk, inspecting the tower legs and struts above the roadway. Struts below the roadway were also inspected by technicians lowered from the sidewalk level.

The size and complexity of the structure has required the inspection team to develop creative and innovative rope rigging to safely and efficiently access the structure and perform a quality inspection. For example, inspectors used tensioned backup lines anchored at intermediate catwalks on the tower legs to counteract heavy crosswinds and keep inspectors in position.

By using industrial rope access techniques, the HDR team has been able to complete all fracture critical and tower inspections without ever closing a lane or sidewalk.

Repair and Analysis Services

Besides inspections, we also provide analysis, repair and load rating services to the District, which recognises our steel repair and analysis expertise as well as our team’s familiarity with the Golden Gate Bridge.