Sunday, June 25, 2017

1983 Hale Boggs Memorial Bridge over Mississippi River at Luling, LA

(Bridge Hunter, John Weeks III3D Satellite (32 photos), formal name: Hale Boggs Memorial Bridge)

LADOTD via ResearchGate

bridges, p50

John Weeks III

Bridges, p5

More info on the barge-mounted 60-foot ringer crane that was created to build the bridge is here.

Ben Stalvey posted
Dennis Gigoux reposted with a lot of commentary
Steve Khail This was another of my photo shoots for Manitowoc. The Luling Bridge was a very high profile project that was also featured in a Budweiser TV ad.

Mike Larson 60' diameter PLATFORM-RINGER, similar to the RINGER that went with a 4600 Series-4 crane, but with the crane replaced with a platform, winches, and counterweight replacing the crane itself. It was designed for applications like this, in which the a company was going to use the machine in one place and didn't need the crane itself.

Anthony Gugliuzza It now belongs to the USACE .
Under Construction, from Bridge Hunter
"The Hale Boggs Memorial Bridge, also known as the Luling Bridge, was the first major cable stayed bridge to be built in the United States. The bridge is somewhat unusual for a cable stayed structure in that is has very few stay cables. In addition, the deck is built like a box girder, which is a much more robust structure than typically seen on suspended bridges....The bridge towers soar 400 feet into the air, with the deck having 155 feet of clearance between the sea-level water and the low bridge steel over the navigation channel." It was designed to survive hurricane force winds and Katrina demonstrated that the design worked. [John Weeks III] As I used to say at work, "being on the cutting edge of technology means you bleed a lot." Between 2009 and 2012 all of the cables were replaced because the original ones were beginning to corrode. The new cables are seven-wire strands coated in grease then encased in plastic. The original 72 cables were sealed with grout before being encased in plastic. The problem was that the grout began to crack and allowed water to make contact with the cables causing the steel to corrode. The new cables did not meet specification and had to be replaced. [NOLA: 1, 2] There were additional problems with rust and water leakage in the anchorages. [Wikipedia, (the ENR reference link does not work)]

A 2008 article:
Luling Bridge rating dropsRusty cables could mean a $20 million repair billBrendan Rush, public information officer for the DOTD, said despite the three structural rating the bridge received recently, it’s safe. Rush said there is a $14 billion backlog in making structural repairs to roads and bridges all across the state.
“When the twin span collapsed (bridge connecting New Orleans and Slidell), we made major changes,” he said. “We made sure that the speed limit got reduced and there was a weight limit for vehicles traveling back and forth across the bridge."
Gill Gautreau, engineer of bridge maintenance for the DOTD has 35 years of experience, and explains the rating. “The Luling Bridge got a three because the cables holding the bridge are bad and need to be replaced,” he said. “What residents need to understand is that this bridge is very unique in its structure and design and it will require a certain kind of bridge repair company to change the cables,” he continued. Gautreau said the Luling Bridge was the first major cable stay bridge in the United States. The cables that support the bridge are deteriorating — they are rusting more rapidly than anticipated and need to be replaced. “We don’t know how long they’ll last as they are,” he told the Herald-Guide. Gautreau said the cables have a multi-task protection system that was good enough in 1983, but is not good for our standards today. “The bridge was designed in the late 70’s,” he said.
“Repairing the cables could be very expensive,” he said. “Replacing the cables would be smarter and that is what we are planning to do.” Gautreau said only one company, has done this type of cable replacement, and they’re located in France.
The cost of replacing the cables is between $10 million and $20 million dollars.
Gautreau said this money will come from the Bridge Replacement Program, money provided by the federal government for bridge repairs.
For right now, Gautreau said, sensors will be used to detect whether or not the cable wires are ready to snap. “There are 72 wires holding up the Luling Bridge. The Fred Hartman Bridge in Houston, TX has a similar system to measure whether or not a cable is getting ready to break, “ he said. “And the laser method will also be used to determine a possible split in the cables.” Gautreau said a consulting firm out of Illinois will be contracting with them to monitor the Luling Bridge. “This bridge is so unique we’ve always had monitors on them to detect cable movement for possible deterioration.”
[HearaldGuide, paycount 2]
So state DOTs can get federal money to repair bridges. This makes the replacement, rather than an augmentation, of truss bridges even more scandalous.

A $30.5m project from 2009-12 replaced the old grout+plastic encased strands with 7-wire, greese+plastic encased strands. The new cables are designed to last approximately 75 years. The replacement cables themselves were replaced after failing to meet specifications! [nola] Another $20.5m was spent in 2016 to resurface the deck.

The plastic sheathing of the original cables was damaged in many of the cables before and during installation.  [ResearchGate] Hopefully, they didn't damage the replacement cables.
They tried fixing the cables, but to no avail. [ResearchGate] The repairs not only wasted money, they would have caused traffic disruptions.
"The new parallel-strand cable system allows individual strand installation, tensioning, inspection and replacement. Due to the suspected poor condition of the existing cables, the construction sequence incorporates temporary cables and detailed analysis of construction." [ascelibrary-replacement]
They also had to design a repair strategy that minimized the impact on the traffic. This bridge is on a hurricane evacuation route. [ascelibrary-evaluation]

The cost was actually $50 and took 2 more years than estimated because they discovered the new cables would not fit in the old holes in the towers. The contractor, Kiewit, picked the large cable design. The French company Freyssinet offered a smaller cable design. The state paid the cost overrun even though many thought it was the contractor's mistake. [wwltv] I recognize Freyssinet as the only company in the world that had done cable replacements by 2008.

In addition to corrosion in the cables and anchorages, there were wind-rain cable vibration issues. [bridges]

The old cables were parallel wires like that used in suspension bridges.
bridges, p8
The new cables are parallel strands. And the plastic is changed from polyethylene to high-density polyethylene. Note the spiral rib on the plastic pipe. That is to reduce wind-induced vibrations.
bridges, p20

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