NTSB Media Brief - 2021 WMATA Train Derailment
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- Опубликовано: 22 май 2024
- January 4, 2024: NTSB Chair Jennifer Homendy briefs the media on the final report of the NTSB investigation of the 2021 WMATA train derailment in Arlington, VA.
@ 23:30 The video was edited due to a medical emergency.
I love that she does not pull punches. As a federal LEO, I would love to see her as head of DOJ.
truth
Wow she is *pissed*. And rightfully so. WAMATA "didn't know" because they didn't want to know.
I appreciate her for being in this position and taking safety seriously. I sincerely hope WMATA has since acted on the recommendations of NTSB
This could have been much worse. I've ridden that line. As a passenger riding that train near where the car derailed would I know there is a derailed car that had re-railed itself? And if I knew that would there be a way to notify the train operator? What if it jumps the track at 50 mph? I think I might want to get off that train at the next stop.
Thank you for sharing the information, findings, and reccomendations. The NTSB does a great job!
Why are wheelsets held together with only friction? Can't they be welded???
My first thought. I also thought the wheels were heated and shrunk onto the axles, in addition to being welded. But for just being pressed is rediculous, i mean, the pressure is considerable, but with side loading in normal operation, it adds up.
Compression fitting, in addition to welding, has its own problems. If it was heated to expand it to make it fit, logic says that as the wheels gain heat and cooling from usage, it is going to weaken the compression fitting through torque stresses. The same principles apply to the welding. Now add on vertical, horiztonal, and lateral movement from use/track composition/navigation, and sooner or later the compression fitting and the welds will fracture from hydrostatic shock/metal fatigue.
It's just quicker, easier to make it as one unit and replace it as one unit. Drop the assembly, use an ultrasonic machine to check for metal fatigue. Inspect the interior of the trucks for bearing wear and metal fatigue. If in spec, reinstall and resume. If not, drop the assembly and/or trucks, replace, reinstall, and good to go.
Welding introduces internal stresses that can make the wheel hub brittle. The wheels are warmed before pressing on to the axle. This isn't a method problem. It is a design deficiency. Increase the interference fit and this problem is solved. Light rail operations don't require robust design like freight railroads do. This was just cutting corners to close.
I can't think of any other country that doesn't safeguards to prevent this.
I've always thought assembling wheelsets with a press fit was a dumb idea.
I love her no sugarcoat attitude. She certainly is right wmata got very lucky. This here is a massive reason why I wish wmata had a bigger amount of 6000 series cars. For increased safety and also so that way this whole 7000 series issue wouldn't have been as bad when it came to service as it actually was. Of course we had no idea this would happen since the 7000 series are always doted on cause of their appearance and all but it would've been smart to prepare just in case.
the NTSB is based
Hi guys...
😲