General MBTA Topics (Multi Modal, Budget, MassDOT)

F-Line to Dudley said:
Blown turbocharger....
maxresdefault.jpg
Click to expand...

A quick Google tells me that that the Amtrak 24 fire happened in May of 2015 in Milwaukee. I know for a fact that it was repaired and returned to service after that, because it's the same locomotive that led the train I took from Chicago to Portland, OR in March of 2017. Incidentally, last Thanksgiving soon after disembarking an MBTA train at Wilmington Depot, it passed me leading another train to another Portland (and I had only made note of the locomotive number a few minutes before because I happened to look at couple of photos of the front of the train that I took in Shelby, MT and Pasco, WA while on the train from Boston to Wilmington). Coincidentally again, I later looked up a video from 2012 that my father took of my mother arriving and getting off the Empire Builder at West Glacier, Montana (to meet up with him, as he was already there) the same exact engine was in the lead on her train too. I'm not the kind of person who looks at and notes engine or vehicle numbers, etc. but I might be now!
 
Anyone got any details on this mornings "derailment" on the C branch? I put it in quotes because I haven't seen any official confirmation beyond some photos of a train distinctly split between two switches. However I suspect it was probably related to the fact C trains were terminating at St Mary's St at the time anyway for weekend track work. Wild guess that the train was trying to switch tracks coming in or out of saint marys and a switch issue caused it?

Only pictures I can find right now: https://mobile.twitter.com/KyleSGibson/status/1155085557690785792
 
HelloBostonHi said:
Anyone got any details on this mornings "derailment" on the C branch? I put it in quotes because I haven't seen any official confirmation beyond some photos of a train distinctly split between two switches. However I suspect it was probably related to the fact C trains were terminating at St Mary's St at the time anyway for weekend track work. Wild guess that the train was trying to switch tracks coming in or out of saint marys and a switch issue caused it?

Only pictures I can find right now: https://mobile.twitter.com/KyleSGibson/status/1155085557690785792
Click to expand...

A Breda. What an absolute fucking surprise.
 
Jouhou said:
What exactly is the inherent design flaw with these that make them prone to this? Is it something that can't be modified adequately to mitigate the risk?
Click to expand...

Well, we don't know what caused this one. The main flaw on the vehicles is the entire center-truck design Breda created. It has entirely too much lateral movement to stay on the tracks with enough reliability. The Type 9's, while superficially similar in having "a" center truck, purged all of Breda's hot-garbage design on it and re-did it with fresh design.
 
^ Type 8 center trucks have a distinct rattle to them. It's a sound that you simply don't hear on a Type 7.

I've often wondered if putting a ton of weight on top of the center trucks would be a quick fix on the Type 8 (obviously at the expense of energy efficiency).
 
The problem with the Breda center trucks is that, because of the low floor, they have no axles and the wheels rotate independently. On normal trucks, the solid axle combined with the conical cross section of the wheels keeps it centered on the track on curves, without slippage (the truck rides higher on the outside, so that wheel is effectively bigger). This problem can be solved with careful engineering of both the truck and the tracks.
 
F-Line to Dudley said:
Blown turbocharger. As bad as it looks in pictures, it's actually a fairly benign failure that will happen from time-to-time. A turbo injects air and fuel into the combustion chamber to increase the power efficiency of an engine...so it is quite literally playing with fire by-design. Therefore, a major failure to the component is going to involve lots and lots of flames.

When a diesel truck or gasoline sports car using a turbo has a failure, the vehicle might go up in flames and be wrecked (more an issue with trucks than smaller vehicles like cars). Boats, aircraft, and locomotives with more robust design usually survive a blown turbo by ejecting the flames and exhaust out the engine stack at little to no interior damage. That's why yesterday's fire looked so incredibly bad from the outside: all the damage was vented to spare the engine room and fuel tanks, and to ensure the fire would go out on its own if it was on a stretch of track inaccessible to emergency personnel.
Click to expand...

F-Line --- a very nice summary of the observable

Tech detail that you miss-stated

A turbo injects air and fuel into the combustion chamber to increase the power efficiency of an engine...so it is quite literally playing with fire by-design. Therefore, a major failure to the component is going to involve lots and lots of flames.
Click to expand...

Not in a a Diesel Engine -- the definition of a Diesel type of Internal Combustion Engine -- an engine which compresses the air with the piston at the point of maximum compression of the air it then injects the fuel which ignites due to compression heating of the air. The other typical internal combustion engine is the Otto-type (gasoline) where the piston compresses an intake fuel-air mixture which is then ignited by a spark.

In the diesel engine [4 stroke] the only time fuel and air are intentionally together is inside the combustion chamber just before top-dead-center when the power stroke begins. Both intake and exhaust valves are closed and the fuel injector fires the diesel fuel into the compressed air. The turbocharger pumps the air into the combustion chamber while the piston is descending before the compression process begins. The details are slightly different for a 2 stroke Diesel Engine*1 such as used in the T's locomotives in question. However, in a Diesel Engine --- Neither the power turbine nor the compressor side of the Turbocharger should ever encounter unignited fuel except in a malfunction.

*1 An intake port which is uncovered and covered by the piston's motion replaces the intake valves, etc.
https://youtu.be/mA7l3dpx6t0
 
Green Line derailment today just outside Riverside. Almost no one aboard. Shuttle buses running (ran?) to Newtown Highlands.
 
You'll never guess, but it was the Breda that derailed. The leading Type 7 stayed on the tracks, from what photo evidence shows. Exactly 1 passenger on board since it was crack-of-dawn.
 
F-Line to Dudley said:
You'll never guess, but it was the Breda that derailed. The leading Type 7 stayed on the tracks, from what photo evidence shows. Exactly 1 passenger on board since it was crack-of-dawn.
Click to expand...

Maybe (probably) a really dumb question, but is there a chance a train with more passengers and their added weight would prevent or reduce the potential of a train like this from derailing?
 
F-Line to Dudley said:
You'll never guess, but it was the Breda that derailed. The leading Type 7 stayed on the tracks, from what photo evidence shows. Exactly 1 passenger on board since it was crack-of-dawn.
Click to expand...

Apparently, it was driver error. Didn't wait tfor the switch to fully engage.

https://twitter.com/wbz/status/1159131956375896064?s=20

This is unusually fast for the MBTA to comment on the cause of a derailment.

My guess is that given all of the operational issues the T has faced over the last month or so, they need to mitigate the PR blows at this point.
 
Lrfox said:
Maybe (probably) a really dumb question, but is there a chance a train with more passengers and their added weight would prevent or reduce the potential of a train like this from derailing?
Click to expand...


I doubt it. This one happened so soon after departing Riverside that there wasn't enough acceleration room to get up to a high speed. Hitting the accelerator full-throttle could've resulted in an overspeed...but it wouldn't have been an extremely fast overspeed.
 
North Shore said:
Apparently, it was driver error. Didn't wait tfor the switch to fully engage.

https://twitter.com/wbz/status/1159131956375896064?s=20

This is unusually fast for the MBTA to comment on the cause of a derailment.

My guess is that given all of the operational issues the T has faced over the last month or so, they need to mitigate the PR blows at this point.
Click to expand...


Or, it was caught on a security camera. This was right on the approach out of Riverside, so the chances it was seen by T employees live as it happened is very high.
 
Per Pesaturo. . .

Derailment was caused by running a red signal on a crossover switch that was thrown in the opposite direction...then splitting the switch. Crossovers in question were this pair a few feet east of the Grove St. overpass. Recall that since Riverside is a terminal station both platform tracks get used for both directions, so those crossovers get heavy usage throughout the service day.

The operator involved was a rookie with barely a month on the job. If this operator had not racked up much D Line time yet where they'd know by instinct that running the red means an instant split-switch derailment, then inexperience likely explains why someone made this rather obvious mistake where it's been almost unheard of for vet operators to do the same.

The spot is uniquely vulnerable in that it requires frequent running against-the-grain into switches that get flipped back/forth all day while nearly all other junctions on the system are go-with-the-flow where switch-splitting is difficult to do. And it happens outside of yard limits where extra onsite staff assistance isn't possible for preventing such an accident (unlike Cleveland Circle, Alewife, Braintree, Oak Grove, Forest Hills, and Wonderland). And Green still doesn't have stop enforcement, so anyone can coast right through that red into the open switch whereas on the 3 HRT lines it's only possible if you floor it into the signalized auto-stop then skid into the switch during the act of stopping. But at least it's very hard to work up much speed a mere 100-200 ft. (depending on which of the 2 crossover had the open switch) from taking off from the platform, so the resulting derailment isn't likely to be damaging to the vehicle or all that unsafe for passengers on board.
 
George_Apley said:
Ultimately this is good news. The amount of work that needs to be done was always going to be disruptive.
Click to expand...

The frustrating part is that no one will note the benefits of the work - they'll just find something else to complain about.
 
You must log in or register to reply here.

Back
Top