Friday, April 9, 2021

TX-8 (Jesse Jones) Bridge over Houston Ship Channel

(Bridge Hunter; Satellite)

Patrick Feller Flickr via Bridge Hunter, License: Creative Commons Attribution (CC BY)

Construction Photo, Aug 2019

In this publication done in 2017 the extimated cost was $550m
Construction is underway on the new precast segmental cablestayed Ship Channel Bridge in Houston, Texas for HCTRA. This world-class signature bridge on the Sam Houston Tollway (East) will replace the existing Jesse H. Jones Bridge, a cast-in-place segmental box girder structure that was built in 1982. Although the existing bridge is in excellent condition, a projected growth in traffic to almost triple what it is today demanded an increase in travel lanes from 2 to 4 lanes in each direction with full 10-foot shoulders and keep the new bridge in existing right of way. HCTRA elected to span the Houston Ship Channel waterway completely to accommodate future widening and deepening planned by the Port of Houston, resulting in a main span length between pylons of 1,320 feet. The 175-foot vertical clearance to the channel matches that of the Fred Hartman cable-stayed bridge located at the entrance to Galveston Bay. [asbi-assoc]
But FIGG, the original bridge designer, claimed the bridge had more than 187' of vertical clearance. [FIGG] They also specify that the long span is 1,320' and the towers are 514' tall. Another vote for 175' is fact #3 on the first image in project facts. The longer approaches reduce the grade even though the clearance is higher.

The drilled shafts for the foundation "range from 42 to 120 inches in diameter and are up to 250 feet deep." [Traylor] Someplace I read it is 10' diameter shafts that go down 250'.

In this 2020 publication the estimated cost was about $1b.
[When the price almost doubles in just three years, something is seriously wrong. FIGG was at least part of the problem. FIGG was fired from this project like it was on the new bridge in Corpus Christi. FIGG was also fired by the Feds: "In July this year [2020], the US Federal Highway Association suspended FIGG Bridge Engineers from participating in federally-funded projects and proposed a 10-year suspension." Furthermore, an independent review cited 21 "significant" design flaws.]

COWI, the engineering firm that was hired to do the independent study, is the one that was hired to replace FIGG. [ConstructionDive]

In addition to a cable stayed design, a billion dollar price tag and the firing of FIGG, this bridge shares another topic with the Corpus Christi Bridge: an accident while lifting a beam. It appears the Corpus Christi Bridge suffered a crane wreck. Comments on the following post indicate that a beam broke for this bridge, But I think the lift cables pulled out of the beam. That would be a construction problem rather than a beam strength  problem and that would not impact the safety of the bridge. I believe the two orange circles are highlighting that the beam lift cables are still hanging from the hooks.
P.K. Williams posted
Houston Ship Channel bridge project just had a beam lift go wrong on the south approach. My buddy heard the noise and the beam was on the ground. Details unknow on any injuries.
Tonia Jackson: My bf works for ship chan they said the beam broke in half.
[Another comment also indicates that the beam broke.]

Construction Photo, Nov 2019
Precast concrete beams are used to span between approach bents.

Construction Photo, Sep 2019
Concrete used for construction of the new bridge is tested before placement.

Construction Photo, Nov 2018
Concrete testing during the pour of a drilled shaft on a southbound North Approach pier.



This is FIGG's advertisement in the ASBI newsletter that featured their Houston Ship Channel design.

I had seen a photo of the long-line formwork system, but then I lost track of where it was. It is the grey thing under the yellow gantry in this photo. Note all of the segments curing in the left rear.  If FIGG's design errors cause those segments to be declared junk, getting rid of them, let alone replacing them, will be a big additional expense.
It is interesting that the newest available photos are a year old.
Construction Photo, Apr 2020
View of the Casting Yard from the Southbound North Approach bridge.

The ground can't support the segments? That is awfully squishy ground.
Construction Photo, Dec 2019
Timber piles serve as foundations for future segment storage.

This shows why the pilings are needed. They are concentrating the weight of the segments at the ends. Other photos show that they support them by the ends so that there is an airgap between the segments and the ground to help them dry and cure.
Construction Photo, Apr 2019
Bridge segments will be stored on stands in the storage yard.

The concrete silos in grain elevators used to be made with a slip-form system. Then they developed a jump-form system where they reuse forms but they don't have to continuously pour the concrete.
Construction Photo, Oct 2019
Each jump form system has two levels and is supported by four towers.

Construction Photo, Aug 2019
Assembly of the gantry crane, steam building and casting bed continues at the Casting Yard.
[Does the steam building clean the rebar cages before they are placed in the casting bed?]

Note that they are using two concrete pump trucks for this pour. 4668 cubic yards is in the same ballpark as the 5000 cu yds for the foundation monolith of the Trump Tower, which was considered a big pour. (Another source puts the Trump Big Pour at 4600 cu yds. So it is not only the same ballpark, it is essentially equivalent.  But Texas is big. A pour for the foundation of a skyscraper in Houston did 13,799 cu yds. in 20 hours with six pump trucks.)
Construction Photo, Aug 2019
Placement of the first lift of the M4 footing was completed in thirty four hours using 4668 cubic yards of concrete.
[The caption on the photo before this one on the web page explains that the hoses in the lower-right corner carry water to control the temperature of the concrete mass as it cures.]

Actually, I see one worker placing, two workers consolidating and four workers watching.
Construction Photo, Aug 2019
Workers carefully place and consolidate concrete for the M4 footing.

I know each pylon had at least two lifts. I don't know if there were more. This lift had even more concrete (5646 cu yds). It looks like the number of workers consolidating concrete is more than the number just watching.
Construction Photo, Jul 2019
The final pour for the M3 footing was completed in forty two hours using 5646 cubic yards of concrete.

This photo shows that the bottom of the beams are prestressed. 
Construction Photo, Jun 2019
Setting girders along the southbound North Approach.
[The photo following this one on the web page showed that the cranes are Manitowoc 888s.]

Why would the first lift of one pylon have significantly more concrete than the other one? (4668  vs 6000 cubic yards)
Construction Photo, Jun 2019
Two concrete pumps were used to place 6000 cubic yards of concrete in the first lift of the M3 footing. [Another caption indicated this pour took 40 hours.]

One advantage of sandy soil for a foundation is that it is easy to trun the augur into the soil. The disadvantage is that the hole has to go really deep.
Construction Photo, Apr 2019

It appears they are not willing to let the concrete simply fall to the bottom of a shaft. I presume the pipe going off to the right goes to a concrete pump truck that probably taps into the pipe before it goes on the boom. I've seen that they can open the pipe near the pump. What keeps the concrete from free falling in the flexible hose?
Construction Photo, Mar 2019
Pouring a drilled shaft for a southbound North Approach pier.

Normally the engine that drives the turning of the drill is on the end of the "black boom." In this case, they have put the engine on top of the crane's weights and used hydraulic hoses to drive the drill. That probably allows them to use a smaller crane because the drive engine is not part of the load that has to be held by the crane.
Construction Photo, Feb 2019
Drilled shaft installation for a southbound Main Span pier.

After they drill a shaft, they line it with steel and...
Construction Photo, Nov 2018
Drilled shaft installation at the north southbound Main Span pier.

...insert the rebar cage.
Construction Photo, Nov 2018
Drilled shaft installation at the south southbound Main Span pier.

Since the shafts are up to 250' deep, some shafts need multiple rebar cages.
Construction Photo, oct 2018
Coupling reinforcement cages for a southbound Main Span drilled shaft.

No comments:

Post a Comment