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Golden Gate Repainting Put Off, Report Says

Tuesday, November 29, 2016

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San Francisco’s iconic Golden Gate Bridge is long overdue for a paint job, according to Bay Area media outlets, which note that the span’s main cable housing hasn’t gotten a wholesale recoating since its original construction nearly 80 years ago.

KPIX-TV first reported Wednesday (Nov. 23) that the Golden Gate Bridge is showing signs of corrosion, and that there is documentation of official recommendations of a repainting job dating back to 1969. The main cables have been spot-painted over the years, but have never had a full paint job since the bridge opened in 1937, according to the outlet.

Stops and Starts

A larger repainting job began in 2011, but was halted early on because the main cable’s hand rails needed to be replaced for safety reasons.

KPIX says in its report that “virtually the entire length of the cable housing appears to show wear and tear.” Bridge manager Dennis Mulligan told reporter Jeffrey Schaub that despite the outside appearance, the cable strands inside the housing are in good shape.

Golden Gate Bridge
By Wa17gs, CC BY-SA 4.0, via Wikimedia Commons

A repainting of the Golden Gate Bridge's main cables started in 2011 but was cut short because the cable's hand rails needed to be replaced.

A member of the bridge’s board of directors told the TV station that, since the last attempt at a major repainting, there have been attempts to restart the project, but other, more pressing issues with the bridge have come up and required resources.

In 2012, during an extensive seismic retrofit project, extensive rust was found on structural steel under the bridge’s wind-lock boxes. This led to a $475,000 expenditure used to address the corrosion.

Meanwhile, “tens of millions of dollars” originally isolated for the bridge repainting in 2011 have since been spent on other projects, according to KPIX. The station reports that budget documents indicate a major repainting project is now planned for 2018, to be finished in 2022.

'Ongoing Task'

Each of the two main cables is 7,650 feet long and, including the exterior wrapping, each main cable is 36 3/8 inches, according to the Golden Gate Bridge Highway & Transportation District.

Golden Gate main cable
By Ronnie Macdonald, CC BY 2.0, via Wikimedia Commons

The bridge, which was always famously been painted International Orange, was originally coated with lead paint, but is now painted using an inorganic zinc primer and an acrylic topcoat.

The District, on its website, notes that “painting is an ongoing task and a primary maintenance job.” The bridge's location over saltwater makes corrosion protection a top priority.

The bridge, which was always famously been painted International Orange, was originally coated with a lead primer and lead-based topcoat, but changing technology over the years has led to changes in the coating system. Most recently, the bridge has been coated using an inorganic zinc primer and an acrylic topcoat, which complies with modern VOC standards.

Suicide Barrier Bids

Earlier this year, the District accepted bids for the addition of a “suicide net,” a steel barrier that would discourage potential bridge-jumpers while maintaining sightlines on the bridge. The lowest bids came in at nearly twice the original estimate for the job.

Earlier this month, the Metropolitan Transportation Commission, a government entity tasked with transportation planning for the Bay Area region, said it likely would step in with an additional $40 million to help defray the suicide barrier costs.

   

Tagged categories: Acrylic; Asia Pacific; Bridges; Corrosion protection; EMEA (Europe, Middle East and Africa); Funding; Government; Latin America; North America; Program/Project Management; Structural steel; Zinc-rich (inorganic)

Comment from Królikowska Agnieszka, (11/29/2016, 2:21 AM)

What was the surface preparation for the inorganic zinc rich primer during maintenance works? What type of primer was used - 1K or 2K, which producer? Agnieszka


Comment from Peter Bock, (11/29/2016, 7:20 AM)

Well-built old bridges like the Huey Long Bridge in New Orleans and the Golden Gate can last for centuries if given timely, proper maintenance, even without the use of lead- and chromium pigmented protective coatings. Continuous, timely maintenance of the corrosion control coatings is the key.


Comment from Michael Beitzel, (11/29/2016, 8:38 AM)

Peter You are right on point with that observation. Two of the best examples of bridges in excellent condition I have seen and both have one thing in common, in house bridge maintenance forces since they were constructed


Comment from peter gibson, (11/29/2016, 10:32 AM)

The GGB has full time painters up there at $50 /hr. per man.Painting year in and year out. Now they tell us the bridge needs a complete recoat. Can anybody tell us what they are doing aloft. Also ,the suicide barrier is a feel-good idea,but everybody knows it won't deter jumpers. A $ 140 mil to feel good.


Comment from Tom Schwerdt, (12/2/2016, 10:40 AM)

Peter, the in-house GGB painters typically take care of ongoing spot and zone repair of the coating system where there is isolated breakdown. There simply aren't enough of them to also perform the occasional large repainting projects that happen maybe once a decade. Contracting those out is probably more cost effective than expanding the in-house forces and purchasing the additional equipment needed.


Comment from Bob Parker, (12/5/2016, 10:00 AM)

I am surprised that the coating system now in use on the GGB is an inorganic zinc primer and an acrylic topcoat. Is this a 2K acrylic urethane finish or a 1K water-based acrylic coating for the topcoat? I know that both are used as topcoats for bridge coatings, but severe environments like this should be using the 2K acrylic urethane for superior corrosion resistance.


Comment from Tom Schwerdt, (12/6/2016, 8:21 AM)

Bob, It may seem counterintuitive but IOZ can often perform better with a more permeable topcoat. Acrylic latex is also a LOT easier to touch up/overcoat than a 2K urethane. This is a perfectly valid option for a coating system.


Comment from peter gibson, (12/27/2016, 10:49 AM)

Bridge jumpers don't know there is a suicide net; and will jump anyway.When in that state of mind,they not thinking about nets. Not like flying trapeze in the circus where you can see a net! More feel good nonsense.The do-gooders aint worried about corrosion ,they want to save lives....good luck. We'll be watching the stats.


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