Eastern Railroad Discussion > Grade Separated Underpass Update 10.12.19 New NS Bridge

Location: Douglasville Georgia
Norfolk Southern East End / Atlanta Terminal MP658
Scope Of Project:
The project consists of a 3.10 mile bypass of hi-way SR92 east of Douglasville Georgia and includes three east/west bridges over the new north/south hi-way. East Strickland Street / NS East End Mainline* / Siding & US78 Bankhead Hwy. On January 30, 2018 during the annual MOW outage of the NS Alabama East End District* the cut in of the shoofly around the railroad's new bridge location took place. That was 21 months ago and the total construction time in the area of US-78 and the NS mainline is currently approaching the 5 year mark.

* It should be pointed out that this section of tracks is maintained by the the Alabama Division but the tracks are controlled and are a part of the NS Georgia Division Atlanta Terminal District* 
Link To Last Post On This Topic. https://www.trainorders.com/discussion/read.php?2,4873636
Link To Next Update on this subject: https://www.trainorders.com/discussion/read.php?2,4901599

Link To Original Post. https://www.trainorders.com/discussion/read.php?2,4233971
With Artist Rendering of the completed project & aerial view. 

Since the last update posted on this project back on September 27, 2019 while the west abutment wall was curing construction crews completed the installation of the re-bars for the East Strickland Street west abutment footer and the footer was poured last week. A second crane was delivered on site, assembled and will be used to set the steel beams for the railroad bridge. 

#1. The west abutment wall with all the forms in place and the cooling system tubing connected is ready for the concrete to be poured. This abutment was poured back on 9/25. See above.. “Link To Last Post On This Topic” 

#2. It is estimated at over 5,000ft of plastic tubing was routed through the re-bars for each abutment within the estimated 35 ft. high form. With all the re-bars and tubing there was little room for the workers to descend into the bottom of the form and then work their way back up as they use several ultra high frequency vibrating units. These vibrating units cause the mixture of cement, aggregate and water to liquefy to help make sure there are no voids and also insure that all air bubbles can escape the pour. 

#3. The connection end to the supply and return headers from the chill water cooling system. 

… more to follow....

Phil Maton
Villa Rica, GA



Edited 2 time(s). Last edit at 06/15/20 04:29 by NSSpike.

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#4. On October 8th the process started for setting the first steel I-beam for the bridge. The two crane operators skilfully raised and rotated the beam 90 degrees from its pick up point and lowered it into place on the two abutment walls. 

#5. As you would expect since the crane booms are facing south in this process the NS RWIC on site has secured track time and no train traffic will pass the area until the cranes booms are at least parallel to the tracks and the “Work Between” TA has been closed out. 

#6. The first beam is close to being set on the east abutment wall. 

… more to follow....

Phil Maton
Villa Rica, GA

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#7. After each beam is set in place, chains and binders are applied to secure the beam in place before the next adjoining beam can be set. Once all the gussets / spacers are installed between the beams the chains and binders can be removed. 

#8. Before the next beam can be maneuvered into place a bare table move, NS 28M to Memphis must head west past the job site. 

#9. On a visit to the job site on Friday of this week I found that six beams had been set with the remaining three beams on site. That's NS 24E (DALLAS, TX (KCS IDAAT2) - ATLANTA, GA) at 9,800ft plus heading east past the job site. 

NOTE: Currently there are two tracks, the main and a non signaled siding. However the new bridge is being built to accommodate three sets of tracks, a third being for future needs. As a result of the limited space within the current excavation area the remaining part (about 15ft) of the bridge will be built sometime after both tracks are placed back to their original location. 

Thanks for stopping by and always be safe in your travels and when out track side!!!

Phil Maton
Villa Rica, GA



Edited 1 time(s). Last edit at 10/12/19 03:50 by NSSpike.

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This is a neat project, thanks for all the reporting.
john

Thank you for the effort. I look forward to your next update.
John

quick structural question here, what exactly is all the plastic tubing inside the form?

after building quite  few forms in my life i have never even heard of anything like that, you said a cooling system,
however im still kinda lost on this one, tyia

CSXperiment Wrote:
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> quick structural question here, what exactly is
> all the plastic tubing inside the form?
>

The below link from back in early September provides some detail related to the tubing and cooling system.
https://www.trainorders.com/discussion/read.php?2,4859950

On large concrete pours for this application it is critical that the temperature of the concrete be controlled between 40-80 degrees F. 
To accomplish this chilled water will be circulated through the tubing that will remain embedded within the entire framework of the pour. 
After about 5 days from the inital pour as the curing process continues the cooling system is shut down. After the cooling system supply 
and return headers are removed the remaining water in the tubing will be pumped out and all the tubing will be filled with a pressurized grout mixture. 

Phil Maton
Villa Rica, GA

Thanks Phil.
I do commercial buildings and big sized footers but nothing to that scale, very interesting

Any large pours where the forms are wider than 2-3 feet the engineers will start to consider the heat of hydration in the design process. As the concrete cures it generates heat and the cool water pumped through the plastic pipes will keep it in the proper range.

Posted from iPhone

As far back as the Hoover Dam in the 1930s, engineers worried about cooling fresh concrete. The dam was built largely of blocks 125 to 300 cubic feet in size. Each block had steel pipes embedded for cooling. An ammonia-driven ice plant was built onsite. After sufficient curing, the pipes were pumped full of concrete. 

ctillnc Wrote:
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> As far back as the Hoover Dam in the 1930s, engineers worried about cooling fresh concrete. The dam was built largely of blocks 125 to 300
> cubic feet in size. Each block had steel pipes embedded for cooling. An ammonia-driven ice plant was built onsite. After sufficient curing,
> the pipes were pumped full of concrete. 

I recall reading that if the dam hadn't been built with a cooling network, its concrete would have been generating heat until the middle of this century. (!!!)

~Joe P.
Hainesville, IL