Retainig wall east of 2014 wall collaspe is failing with sidewalk and parts of road being mitigated . CSX working to prevent complete collaspe . Report that train traffic temporary suspended.
https://www.baltimoresun.com/news/maryland/baltimore-city/bs-md-ci-east-26th-sinking-20181126-story.html
Sometimes that "free land" given away to build a railroad line in/through a town, isn't the bargain it is made out to be. Not sure if this is the case here or not. It just seems that way after seeing how many swamps the railroads built through back in the day.
rrnut282Sometimes that "free land" given away to build a railroad line in/through a town, isn't the bargain it is made out to be. Not sure if this is the case here or not. It just seems that way after seeing how many swamps the railroads built through back in the day.
Retaining wall was built back in the 1890's when B&O built the Howard Street Tunnel and the Baltimore Belt Line to run from Camden Station to Bayview and connection with the rest of the line to Philadelphia.
To date, Baltimore has experienced the 'wettest year on record' with over 65 inches of precipitation having been measured - previous record in 2003 was shy of 63 inches - the year still has 5 more weeks. This November, to date, also has the distinction of being the wettest November on record.
Ground reacts when it gets wet, really wet.
Never too old to have a happy childhood!
Sounds like 1890 retaining wall's expected design life was exceeded.
Question that needs to be asked: What is the story of development and growth behind the trench? (largely geotechnical & buried utilities) Besides wet weather, what else contributed in terms of bad engineering practice? (just like the other wall liquifaction fail and the Howard Street tunnel fails, there is more going on at the site than is being noted by the newsworker's article. Railroad is most likely still frustrated about what it cannot control out beyond the R/W line.)
mudchickenSounds like 1890 retaining wall's expected design life was exceeded. Question that needs to be asked: What is the story of development and growth behind the trench? (largely geotechnical & buried utilities) Besides wet weather, what else contributed in terms of bad engineering practice? (just like the other wall liquifaction fail and the Howard Street tunnel fails, there is more going on at the site than is being noted by the newsworker's article. Railroad is most likely still frustrated about what it cannot control out beyond the R/W line.)
Local news is reporting that there is a demarkation line between where there is CSX ownership and maintenance and where there is city ownership and maintenance. The failures have been in the city owned areas - not CSX.
Who built the retaining wall and who owns it? Which side of the demarkation line is it on? It sounds to me like a new, and properly engineered retaining wall is needed with proper drainage and soil mechanics behind the the wall to reduce the potential pressure that the bank can exert on the wall.
This would require excavating and removing the bank material a considerable distance back from the wall, perhaps as far as 50 ft. The entire volume of soil that is slumping due to water saturation must be removed. Then, once the new wall is finished, a process of backfill and compaction of compactable, free draining soils would be done. Maybe anchors would also be set in the bank to counteract any wall tipping force that develops in the future. This sounds like a project that would cost over $50 million.
A lot of retaining walls have been built with no thought except to stand a wall on the ground and backfill the loose soil back behind it. They always fall over because a retaining wall must include an whole new bank system as well as the wall itself. This CSX wall is displaying the symptoms of a wall that never had the bank improvement necessary, and is now failing.
Every time the bank soil gets saturated over the years, it moves a little, and then dries and stabilizes. But each time it moves, it becomes more loose and fractured; and more able to absorb water from each rain. The failures that are seen in the photos are just the recongition of a problem that began when the wall was built.
What did the Romans know about building retaining walls that we don't? Why do theirs seem to last, while many of ours don't? Why do stone walls last so much better than concrete ones? Why use concrete for them in the first place? How is drainage behind a wall dealt with?
I'm no engineer, but it does seem to me that putting a street or roadway right above the edge of a retaining wall is asking for trouble, however as Balt points out, 2018 has been an exceedingly wet year and yet this wall has lasted for well over a century.
General are overview
https://www.google.com/maps/@39.3189355,-76.6115565,707m/data=!3m1!1e3
Pictures of Act 1 collapse from 2014
Act II
NKP guyWhy do stone walls last so much better than concrete ones? Why use concrete for them in the first place? How is drainage behind a wall dealt with?
There is actually an advantage in having a properly constructed and drained road above the ground behind a retaining wall. On the other hand, a good concrete wall will have ties well back into the soil behind it -- I see none in the picture -- and will have careful drainage at several levels into wicks or small drain tubes cast through the concrete communicating with the railroad ROW drains.
Stone retaining walls may have better foundations and care in their construction, and the stone itself may weigh more than cement+aggregate+reinforcement, but unless similarly tied-back and drained a stone wall would probably have moved about the same as a cast-in-formwork concrete one. And perhaps more easily, if the walls on the PRR embankment through Mount Union are an indication of 'best practice' on the PRR at the height of its power...
While roads are good at shedding water, it's the storm drains that eventually leak unseen that generally cause problems.
Have to agree with Midland howerver we need to go further. Everything that is pipe below ground will leak; some pipe more than others. Let us start with drainage.
The storm drains built before 1920 -30 or so probably were built with terra cotta pipe. That breaks easily and each break will leak rainwater . cracks on the down side will leak when any water enters such as car washing. Then you have the sanitary sewers same problem same results, Then you have potable water lines. Until WW-2 most were cast iron. Cast iron breaks or cracks easily with very litter deflection. Then you have terra cotta telephone service conduit and abandoned telegraph underground services that can also crack and leak water into the ground. Even modern potable water lines of steel or PVC pipe can leak that were or are installed with connecting bells that are too short and can pull apart. Also the bells can have the seals ( early ones were rubber ) to leak.
Now add in the excess rainfall Balt mentions and you get a receipt for disaster
Take all the above no matter how much anchoring is done to a retaining wall if the water presure becomes too much something has to give. As previously posted french driains at various points to drain the back water pressure are very important . MC can tell us when RRs started installing the same ?
EDIT All these problems are the reasons RRs and most highway departments require all utility services to be encased within a steel pipe so any leakage runs out the end of the casement instead of leaking into the subgrade.
Lab, "Roman walls were not built by the lowest bidder". Oh, now that's priceless and so true. Lab, that one made my day.
Bob
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So the issue is that a retaining wall designed in 1890 didn't have enough weather data to predict how saturated the soils could get. That, to me, isn't a failure on anyone's part.
BaltACD Retaining wall was built back in the 1890's when B&O built the Howard Street Tunnel and the Baltimore Belt Line to run from Camden Station to Bayview and connection with the rest of the line to Philadelphia. To date, Baltimore has experienced the 'wettest year on record' with over 65 inches of precipitation having been measured - previous record in 2003 was shy of 63 inches - the year still has 5 more weeks. This November, to date, also has the distinction of being the wettest November on record. Ground reacts when it gets wet, really wet.
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