Are the 7000 series damaging Metro's tracks?

[davinp]

The Federal Transit Administration inspected the Green Line and found broken fasteners "designed to reduce the magnitude of vibrations transferred to the tunnel structure and the environment above."

According to the report, "The use of the 7000-series rail car trains which weigh significantly more than the previous series rail cars and the location adjacent to a station in which trains are applying additional force by braking or accelerating could be contributing factors."

http://wjla.com/news/local/fta-blames-b ... -vibrating" onclick="window.open(this.href);return false;

[STrRedWolf]

That would actually make sense. If the fasteners are only spec'ed to the lighter trains, they'll need to upgrade all the fasteners before running more 7000's.

And that, my fine folk, means more SafeTrak work into 2020!

[Sand Box John]

"STrRedWolf"
That would actually make sense. If the fasteners are only spec'ed to the lighter trains, they'll need to upgrade all the fasteners before running more 7000's.

The solution won't be quite that simple. WMATA uses fasteners of different designs from a verity of different vendors. This may be a surprise to you, there are fasteners in the some of the oldest parts of the system where there have been no vibration issues that were installed before the segments opened.

[smallfire85]

The rail fasteners can handle the increased loading of the 7000 cars. If that wasn't the case we would be hearing complaints from a more widespread area than one specific neighborhood on the Green line.

The news report is misconstruing the info. In the FTA report, it notes that there were broken rail clips observed in certain areas, not broken fasteners. That area is tangent (straight) track about 1000 feet of the platform. As long as there is no rail profile issues and the rail is seated properly, a couple broken clips won't cause major rail degradation in a short time. Broken fasteners would.

What interests me is the almost afterthought of the moderate tunnel leak also found in the area. Could that have an impact on the track conditions, which in turn could cause vibration issues that didn't seem to exist until almost a year ago now?

The FTA report referenced by the article is the December 2016 inspection report. I couldn't get the URL to work properly.

[Chris Brown]

Why would WMATA sanction the design and proceed to PURCHASE railcars that are not fit to run on the existing infrastructure?

This would take a level of stupidity beyond comprehension.

[MCL1981]

Never insinuate WMATA can't possibly get any stupider. They seem to interpret that as a challenge.

[schmod]

The spec'd weight on the 7000-series is 80,000 pounds per car (compared to 72,000 pounds for the 1000-series). I've also seen 85,000 pounds listed as a figure.

Either way, it's heavier, but not by a whole lot. An "average" 7000-series car is still going to weigh less than a completely-full 1000-series car.

I've noticed that the new cars are louder, making a distinct booming noise as they pass by or pull into a station. I wonder if there's an issue with the design of the trucks?

[Chris Brown]

I've noticed that the new cars are louder, making a distinct booming noise as they pass by or pull into a station. I wonder if there's an issue with the design of the trucks?

I've noticed the extra noise is not as bad as it used to be. The cars seem to have quieted down somewhat, but they are still louder than the rest of the fleet. I think its more a wheel/truck issue than a weight issue since a full 1k train would still outweigh an empty 7k train