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  • Red line tunnel problems

  • Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.
Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.

Moderators: mtuandrew, therock, Robert Paniagua

 #1209206  by afiggatt
 
Washington Post article on the need to possibly shut down a portion of the Red Line that provides more information: Metro weighs options for fixing Red Line water leak. If they have to shut down the tunnels, it would not be for months from now, if not a year or more. I wonder if it would be possible to do much of the work while single tracking the segment they are working on, but it the segment is one tunnel box with 2 tracks that might not be feasible.

I do find it curious that this news came out late Friday afternoon. That is when government agencies often release embarrassing reports or bad news, so it gets less press attention and fewer people see the news, and the story is old news by Monday. But if WMATA has to shut down a portion of the Red Line for a month or longer, can't bury that news.
 #1209252  by Sand Box John
 
"afiggatt"
Washington Post article on the need to possibly shut down a portion of the Red Line that provides more information: Metro weighs options for fixing Red Line water leak. If they have to shut down the tunnels, it would not be for months from now, if not a year or more. I wonder if it would be possible to do much of the work while single tracking the segment they are working on, but it the segment is one tunnel box with 2 tracks that might not be feasible.


The leakage in question is in bored tunnels not twin box tunnels. To be precise most of the leakage is in the crossover galleries making single tracking a difficult option.

I do find it curious that this news came out late Friday afternoon. That is when government agencies often release embarrassing reports or bad news, so it gets less press attention and fewer people see the news, and the story is old news by Monday. But if WMATA has to shut down a portion of the Red Line for a month or longer, can't bury that news.

This is not new news. WMATA has been dealing with this water infiltration problem going on 10 plus years now. I have seen numerous documents on wmata's web site that make mention of the problem. It has only become a story because WMATA took somebody from the media out to see the problem with their own eyes.
 #1296340  by JDC
 
So, Metro announced this past week that during 7 consecutive weekends in fall 2016 it will close the Bethesda, Medical Center and Grosvenor stations in order to permanently fix the water intrusion issues.

According to the NBC Washington article, "Metro called in engineers and transportation experts from around the world to find a solution to the water infiltration. The planned fix is basically putting in a "false roof" on the tunnel outside Medical Center. 'We will be coming in with these pre-cast panels which will interlock into place and will provide a shell that will be waterproof. It will provide a better drainage so that the water will go on the outside and won't drop on the track,' Troup said." http://www.nbcwashington.com/news/local ... 53791.html

The NBC Washington article has an accompanying video with an animation of the installation of the 'false roof'', which raises several big questions in my mind. Is this false roof permanent? It looks like it, which means the end of the coffered ceilings in these stations and maybe a look more like the newer Green/Yellow line stations with the less dramatic coffers. What about all of the water intrusion that comes from elsewhere, including in the tunnels themselves? This fix seems to just solve water falling from the ceiling in the vaults and not the water gushing from near the track bed or in the tunnels leading into the stations.
 #1296383  by Sand Box John
 
"JDC"
So, Metro announced this past week that during 7 consecutive weekends in fall 2016 it will close the Bethesda, Medical Center and Grosvenor stations in order to permanently fix the water intrusion issues.

According to the NBC Washington article, "Metro called in engineers and transportation experts from around the world to find a solution to the water infiltration. The planned fix is basically putting in a "false roof" on the tunnel outside Medical Center. 'We will be coming in with these pre-cast panels which will interlock into place and will provide a shell that will be waterproof. It will provide a better drainage so that the water will go on the outside and won't drop on the track,' Troup said." http://www.nbcwashington.com/news/local ... 53791.html

The NBC Washington article has an accompanying video with an animation of the installation of the 'false roof'', which raises several big questions in my mind. Is this false roof permanent? It looks like it, which means the end of the coffered ceilings in these stations and maybe a look more like the newer Green/Yellow line stations with the less dramatic coffers. What about all of the water intrusion that comes from elsewhere, including in the tunnels themselves? This fix seems to just solve water falling from the ceiling in the vaults and not the water gushing from near the track bed or in the tunnels leading into the stations.


I can't see the video clip because of some issue with my XP box and their Flash rendering coding.

My understanding is the water intrusion problem is primarily in the crossover gallery not the station itself. It would make sense to install a permanent 'false roof' in the crossover gallery but not in the station as the existing arch vault is a 'false roof'.

Image
 #1296579  by JDC
 
Ah, page 8 of the pdf makes clear something I didn't realize: the crossover is itself in a vaulted section of the Red line, versus just in the tunnels. The NBC animation made it appear that the new ceiling being installed was in the Medical Center station itself, not in the crossover area.

Edit: I just read John's helpful post carefully and see he also clarified the issue was in the crossover gallery not the station itself. John - how many crossovers are in galleries, versus just tunnels? From experience on the lines I ride, I thought all crossovers were just in tunnels.
 #1296691  by jkovach
 
The presentation says the work will require 14 weekend shutdowns, not 7. The first 7 shutdowns are for prep work. The final 7 shutdowns will be for the actual installation of the inner roof, and will need to take place on consecutive weekends.
 #1296703  by Sand Box John
 
"JDC"
Ah, page 8 of the pdf makes clear something I didn't realize: the crossover is itself in a vaulted section of the Red line, versus just in the tunnels. The NBC animation made it appear that the new ceiling being installed was in the Medical Center station itself, not in the crossover area.

Edit: I just read John's helpful post carefully and see he also clarified the issue was in the crossover gallery not the station itself. John - how many crossovers are in galleries, versus just tunnels? From experience on the lines I ride, I thought all crossovers were just in tunnels.


Along the A route end of the Red line north of Farragut North, all 4 of them. Dupont Circle, Van Ness, Friendship Heights and Medical Center. On the B route end, Forest Glenn and Wheaton, they are semi galleries. All of the remainder of the double crossovers in subway are in cut an cover concrete tunnels.

Semi galleries as in galleries over the turnouts and the diamond crossing in the center of the double crossover. The 5 smaller galleries 1 for each of the 4 turnouts and 1 for the diamond crossing are connected by short tunnel segments that are the same dimension as the mainline tunnels. The reason for the semi galleries is because of the broader track centers along the B route end of the Red line to accommodate the separate single track single platform station arch vaults.

Mind you the B route end doesn't have water intrusion issues as the entire length of the route, tunnels, stations and crossovers were water proofed using the geomembrane system as described in option 1 when they were originally built.
 #1332361  by Sand Box John
 
WMATA posted a Request For Proposal for the proposed water infiltration fix:

Solicitation RFP: FQ15093/GG
Rehabilitation of Red Line Metro Rail System from Friendship Heights Crossover to Grosvenor-Strathmore Station
(North end wall Friendship Heights to north end wall Grosvenor.)
Posted on 04/16/2015
Due on 06/19/2015

Volume 3 - RFP Drawings_Part 1b of 3.pdf (15.3 MB PDF file) drawing for the water infiltration umbrella over the Medical Center A10 double crossover.

The project also includes the construction of the second entrance to the Bethesda station to support the Purple line station.

Volume 3 - RFP Drawings_Part 1d of 3.pdf(13.5 MB PDF file)

All 59 files total 583 MB
 #1379286  by JDC
 
Metro has decided NOT to repair the tunnel segment on the Red line that has constant water infiltration. Apparently all of the bids came in much, much higher than what Metro was willing to pay. http://www.bethesdamagazine.com/Bethesd ... efinitely/. So, it will do nothing permanent but continue to spend several million dollars each year addressing the effects but not the cause.
 #1379290  by srepetsk
 
JDC wrote:Metro has decided NOT to repair the tunnel segment on the Red line that has constant water infiltration. Apparently all of the bids came in much, much higher than what Metro was willing to pay. http://www.bethesdamagazine.com/Bethesd ... efinitely/. So, it will do nothing permanent but continue to spend several million dollars each year addressing the effects but not the cause.
Just to clarify, it seems they only received 1 single bid. Which strikes me as a little odd, because there seems to have been plenty of interest in the pre-bid phase:
 #1379388  by STrRedWolf
 
I think the reason for the added cost got buried in the headline. Fair use quote from the article;
Metro has also said it is trying to coordinate the project with the Purple Line, which is scheduled to start construction late this year, in order to sync the repair work with construction of the Bethesda Metro station’s south entrance elevator bank. The six-elevator system will transport riders between the Bethesda Purple Line and Metro stations.
What makes you think they wanted them to time it just right?
 #1379414  by Sand Box John
 
"srepetsk"
Just to clarify, it seems they only received 1 single bid. Which strikes me as a little odd, because there seems to have been plenty of interest in the


Me thinks those that showed interest and didn't submit bids went back to their shops and ran the numbers and concluded that they could not execute the work that need to be done in time specified at the price WMATA engineering staff was estimating.

I thing a cheaper option might be to fabricate polyester coated steel frame with a corrugated sheet metal roof on it. Attach that to the gutter and drainage system that doesn't require the moving of the cables attached to the tunnel walls to install. I Believe the thing could be installed piecemeal without the need to shut the railroad down on weekends.