What exactly is the welding supposed to accomplish as a fix to this "too wide, too narrow" dilema? In reading between the lines, I assume the point is to make the wheels 1/2" wider by building up the sides of the non-flange-side of the tread.
I guess this would save the cost of buying new wheels and replacing them on the axles. Obviously, that would be a signficant cost. But what about the cost of all that welding? By their announced intent to recruit a large number of welder persons, it sounds like this will be a hand-held welding process. With the gigantic amount of welding to be done, what will it cost? It may be cheaper to just buy and replace new wheels.
In order to get welding production as high as needed, and to control weld quality control, it would seem preferable to use fixtured robotic welding to perfectly execute the weld buildup on each wheel.
But even with that efficiency, there would still need to be a lot of science and testing in the process to make sure that when the hundreds of wheels are completed, there is no technical problem that requires them to be done over.
BEAUSABRE Can you say "Pork Barrel", kiddies?
Can you say "Pork Barrel", kiddies?
BEAUSABRE Euclid. You seem to think the purpose of the exercise is to provide transportation. It ain't. It's to shovel money out to contractors and the unions. Think of the double and triple overtime to "fix the problem" “The system is still being built with a projected opening of 2 to 10 years.” Ten freaking years?! For 2o miles?! And growing from $4B to $12,5B?! Does that sound like a serious transportation project to you? I mean we made it from Council Bluffs to Sacramento in four years – and that was done by pick and shovel! It makes California's Mixed Speed Rail seem the height of sanity and fiscal fugality. We're doomed....doomed, I tell you.
Euclid. You seem to think the purpose of the exercise is to provide transportation. It ain't. It's to shovel money out to contractors and the unions. Think of the double and triple overtime to "fix the problem"
“The system is still being built with a projected opening of 2 to 10 years.”
Ten freaking years?! For 2o miles?! And growing from $4B to $12,5B?! Does that sound like a serious transportation project to you? I mean we made it from Council Bluffs to Sacramento in four years – and that was done by pick and shovel!
It makes California's Mixed Speed Rail seem the height of sanity and fiscal fugality.
We're doomed....doomed, I tell you.
Oh I hear you. It sounds like the army of welders is going to make the wheels wider by building them up with weld. Yikes. By the time the welders finish, they will need an army of grinders.
The notion that they will save the cost of replacing components involved in this 1/2" gap mystery by a massive welding drive is just bizarre. Do they have a professional engineering team with tecnnical drawings, or is this all being designed in meetings with equipment vendors?
Former Car Maintainerit seems per the news article that HART was more interested in establishing a "Island Based rail welding contractor"
mudchicken FTA has no specs .... Anything goes. The local transit operations create their own rules.(the problem with FTA in a nutshell is transit can largely ignore FRA rule if it suits them - the issue gets worse when you introduce historic transit into the mix (not an issue here)
FTA has no specs .... Anything goes. The local transit operations create their own rules.(the problem with FTA in a nutshell is transit can largely ignore FRA rule if it suits them - the issue gets worse when you introduce historic transit into the mix (not an issue here)
I remember a story about Adm Rickover, who insisted he be aboard the sea trials of every new nuclear submarine. On one occasion, the lead ship of a new class reported a hot bearing on the prop shaft. He went aft, studied the bearing, listened via a stethoscope, studied the drawings and pronounced, "There is nothing wrong with this bearing. It's performing exactly as designed. It was just designed wrong"
mudchicken Former Car Maintainer Newest fix: Narrow the frog gap by using local welder talent...until a wheel size decision can be made?... https://www.staradvertiser.com/2021/10/05/hawaii-news/hart-officials-have-no-answers-for-oahu-rails-door-wheel-track-problems/?HSA=32c046acc9c68c3a39d8981bfb3207de012ec93f FRA check gage violation (Guard and Face) ... Don't go there. The only thing that saves them is FTA jurisdiction and the fact that FTA is deaf/dumb/blind when it comes to track safety. (FTA has no track safety rules to speak of, compared to FRA) Hope nobody gets hurt until they figure out this is a bad idea.
Former Car Maintainer Newest fix: Narrow the frog gap by using local welder talent...until a wheel size decision can be made?... https://www.staradvertiser.com/2021/10/05/hawaii-news/hart-officials-have-no-answers-for-oahu-rails-door-wheel-track-problems/?HSA=32c046acc9c68c3a39d8981bfb3207de012ec93f
Newest fix: Narrow the frog gap by using local welder talent...until a wheel size decision can be made?... https://www.staradvertiser.com/2021/10/05/hawaii-news/hart-officials-have-no-answers-for-oahu-rails-door-wheel-track-problems/?HSA=32c046acc9c68c3a39d8981bfb3207de012ec93f
FRA check gage violation (Guard and Face) ... Don't go there.
The only thing that saves them is FTA jurisdiction and the fact that FTA is deaf/dumb/blind when it comes to track safety. (FTA has no track safety rules to speak of, compared to FRA)
Hope nobody gets hurt until they figure out this is a bad idea.
Are FRA and FTA specs for wheels and track that different to create a 1/2 inch difference when wheels go over frogs?
Never too old to have a happy childhood!
Keep in mind that the track gauge involved with the 'compromise' wheels was 4'10", so the wider tread was only ¾" per side. As Ron noted this could cause effects of oscillation to develop under some circumstances. What I recall about Angola was that the problem started with derailment caused by a bridge guard rail set what turned out to be too close to the flange face... an interference effect that may well apply to the system in Hawaii if the frogs are too far out and the flanges too far in, as I understand the reports to be saying.
Samuel Johnston Compromise Wheels?? As in The Angola Horror (1867)?? Congress made Compromise Wheels illegal in Interstate Commerce (the Constitution remember states as an "enumerated power" that Congress may regulate Interstate Commerce!) very quickly. This very weekend I will be saying two days in Angola NY which has a display in Downtown Angola on the Angola Horror.
Compromise Wheels?? As in The Angola Horror (1867)?? Congress made Compromise Wheels illegal in Interstate Commerce (the Constitution remember states as an "enumerated power" that Congress may regulate Interstate Commerce!) very quickly. This very weekend I will be saying two days in Angola NY which has a display in Downtown Angola on the Angola Horror.
I thought this may be similar to the effect that is occurring with the railroad defect that is the subject of this thread, but I have not been able to interpret this and other references to that problem.
Former Car MaintainerToo thin or too wide?
Both being mutually out of spec would account for the issues. Interesting to see if both have to be remediated... and at whose expense... to fix the situation safely.
Latest spin for the over budget HART:
The door malfunction follows revelations earlier this year that HART’s trains each were running on 32 wheels that were too narrow for track “frogs” that are half an inch too wide at 12 junctions where the tracks cross one another.
Too thin or too wide?
I'd be looking for where FTA has issued an exemption for both the wheel design and the flange bearing frog. (FRA over on the common carrier side is adamant about the rail/wheel interactions around frogs (guard face gauge, guard check gauge and depth/width of the flangeway) -there is an exemption that comes with some pretty steep requirements and plenty of testing/evaluating where there are fbf's)
The wheel tread, speed and the lesser flange width just sound like a recipe for truck hunting troubles from somebody on the heavy haul/ common carrier side. FTA is still a chicken-outfit with serious integrity issues for a reason. They need to be more than just a pa$$-through for federal fund$ to local short sighted non-railroad transportation agencies who don't want to or know how to railroad safely. Stuff they allow would never pass muster at FRA and the failings seem to appear on a regular basis.
mudchicken Turnout size (including the speed) is a simple physics determination based on the turnout curve between the heel of the switch and the toe of the frog. Movable point frogs do more to protect wheel damage to the frog and smooth the ride than anything else.
Turnout size (including the speed) is a simple physics determination based on the turnout curve between the heel of the switch and the toe of the frog. Movable point frogs do more to protect wheel damage to the frog and smooth the ride than anything else.
As I understood it, The problem was first discovered with excessive wear on the frogs, because of the frog guard could not steer the narrow flanges into the correct crossing position. A moveable point frog may have eliminated this. Upon further reading, the vehicle wheels were manufactured by the car builder (someone other than Hitachi who acquired it). Also the 7 or so crossovers were ordered and installed from different builders and installing contractors. Also, since the system is a "first" for autonomous, the FTA is putting it through rigorous testing...
It may be the problem is that the wheel gauge is less than it shoud be ? I would really like to know the track gauge and wheel guage. Maybe all that is needed is to remove wheel from axels and place a sim on each end of the axel ?
Not being an expert the mention that wheel rims are climbing the guard rails seems to indicate that the wheels are less than track gauge.
Euclid Is it in operation now, or just under construction and testing? How do they test it? Is this autonomous operation? Will the operational speed limit be 55 mph? Has the method of fixing this wheel problem been adopted, or is it still under consideration?
Is it in operation now, or just under construction and testing? How do they test it? Is this autonomous operation? Will the operational speed limit be 55 mph? Has the method of fixing this wheel problem been adopted, or is it still under consideration?
On another note, nothing has been mentioned about the frog size numbers and how that plays into it... http://armytransportation.tpub.com/Tr06711/Table-I-Permissible-Speeds-Through-Various-Turnouts-52.htm
Perhaps a movable point frog is the solution...
Many great observations. First I might comment...HART is a design, build, maintain project...so premature frog wear will be on the builder. Second, HART is a two track mainline operation, usually with each track going in an opposite direction, with crossovers ocasionally used instead of routinely used. The train control system could be easily programmed for a speed reduction through the frogs. Third, the HART management has politics written all over it. When completed, HART will appear as a blight to the city skyline, fail to allieve roadway congestion, and only serve to line the pockets of residential developers wishing to build mega communities in the H2 corridor Farmland.
I have googled several articles on this wheel problem, and have yet to find any explanation that does not convey a multiple, conflicting meaning of the problem. They refer to wheels width being wrong, wheel flanges being too thin, wheel flanges being too narrow, and the track being too wide. One article in the OP, it says that the flanges hit the guardrails of the frogs.
If that photo showing ½” gap is taken with the wheelset centered on the track, that means that there is 1” of free play side-to-side for the trucks. As Overmod points out, the flanges seem to be made quite sharp, and lack a fillet radius at their base, and the wheel seems to lack taper; and such taper would allow the wheel to rely less on the flange for guidance.
This lack of a flange fillet radius is equivalent to worn flanges in railroad practice. In that case, the entire side of the flange comes to bear on the side of the rail when the wheel shift is arrested by the flange. This larger contact of flange to rail causes the flange to exert lift on the wheel. If the side force is great enough, the excess flange contact can lift the wheel off of the rail, and allow it to climb over the rail and derail.
Note the photo in the article in the first post shows the flange contact wear extending over most of the flange face on the gage side. This is the excessive flange-to-rail contact that you get when most of the fillet radius between the wheel tread and the flange face is omitted as it is in this design.
So there are two problems:
The wheelset gage is smaller than the track gage.
The wheel profile is dangerous because the tread is too narrow, the tread lacks taper, the flange lacks a sufficient fillet radius, and the flange face is parallel with the side of the rail head.
Also, the two problems work perfectly together to combine their danger. The gage discrepancy between the track and the wheelsets provides a lot of space for oscillation, and the poor wheel profile lacks the features that combat oscillation. This is a perfect recipe for wheels climbing over the rails.
It is the exact fundamental flaw that was discovered with the infamous “Compromise Cars” that were used in the late 1800s to allow wheels to run on two or different gages (4’-8.5” and 4’-10”) that were in use at that time. A major train wreck known as the Angola Horror occurred in 12/18/1867. It killed 49 people. The use of Compromise Cars played a role of adding instability to one of the cars.
https://en.wikipedia.org/wiki/Angola_Horror
dpeltier the problem is that the wheel flanges are a half inch "too thin" for the flange-bearing frog design, and that the observed symptom was excessive frog wear. Also, the issue only affects trains taking the diverging route.
"Half an inch too thin" as a description is one of those things like the old joke in "Meet the Applegates" -- the admonition 'You can't have too much water in a nuclear reactor'. Any attempt to figure out what Bob Good actually intended (and I am reasonably sure that he does know what the situation is, and understands the physics involved) is lost in wack semantics and, apparently, the usual news desire to find blame for when the "experts" screw the pooch.
Still undocumented is a critical issue involving the "silicone coating" supposedly banged or stripped off key portions of the frog architecture -- it still having been left unexplained why such material was necessary in the first place -- and any indication whether it is continuous or oscillating force causing the damage.
I suggest gently that the next person wishing to debunk this kerfuffle actually find a transcript of Good's actual language -- or actually try to contact him, now that he's been identified, or Prof. Prevedouros -- and find out in actual engineering terms what the heck is actually going on.
And then what they and Hitachi might plan to do about it.
BaltACD My understanding that where freight railroads have frogs bearing the weight of the wheel flange in railroad crossings at grade - that route is done at a slow speed. Trying to use the frog bearing the weight in a relatively high speed crossover is like presenting a stick of butter to a hot knife. The impact pressure of the flange against the frog acts like a powered knife over time.
My understanding that where freight railroads have frogs bearing the weight of the wheel flange in railroad crossings at grade - that route is done at a slow speed.
Trying to use the frog bearing the weight in a relatively high speed crossover is like presenting a stick of butter to a hot knife. The impact pressure of the flange against the frog acts like a powered knife over time.
Probably the most common application of a flange-bearing frog is the "jump frog" or "lift frog", used on a low-speed, low-tonnage route that either diverges from or crosses over a heavier-tonnage route. Any disadvantages or maintenance issues associated with flange bearing are dwarfed by the benefits on the heavier line.
Another usage I know of is in yards, where "hybrid flange- and tread-bearing frogs" are used in some pretty high-tonnage situations. These are basically regular cast frogs with a shallower-than-normal flangeway, so that worn wheels with tall flanges run on the flanges while newer wheels run on the treads. (The worn wheels are the ones that cause the biggest impacts and most damage in a tread-bearing frog.)
Then finally there are some crossing diamonds that are fully flange-bearing in both directions. Development of these was hindered for a long time by FRA regulations, and I don't think they have caught on very widely. The flange-bearing sections due tend to wear quickly. And you do still have some impact load where the wheel transitions from tread-bearing to flange-bearing or vice versa.
But a feature of the hybrid frogs and the fully flange-bearing diamonds is that, if the flangeway wears too deep, the whole thing just reverts to a traditional tread-bearing frog. So it doesn't result in any safety problems.
Dan
dpeltierFolks, in the time you spend writing wild and crazy speculation on the Trains forum, you could have used Google to find the following article: https://www.civilbeat.org/2021/03/hart-hitachi-at-odds-over-wheel-defect-as-rail-costs-soar/ And you would have seen that the problem is that the wheel flanges are a half inch "too thin" for the flange-bearing frog design, and that the observed symptom was excessive frog wear. Also, the issue only affects trains taking the diverging route. This still isn't a full explanation, but it rules out most of the malarkey generated so far on this thread. In the freight world the tolerances for allowable wheel profile - and the reality that out-of-spec wheels can travel some ways before getting caught - mean that you would never design a system that relied heavily on the wheels having a particular flange width. So I can't really envision exactly what the problem is. It's not really clear to me from the article whether this is actually a safety issue (trains could fall off the tracks) or an economic issue (frogs have an unacceptably short life). Dan
https://www.civilbeat.org/2021/03/hart-hitachi-at-odds-over-wheel-defect-as-rail-costs-soar/
And you would have seen that the problem is that the wheel flanges are a half inch "too thin" for the flange-bearing frog design, and that the observed symptom was excessive frog wear. Also, the issue only affects trains taking the diverging route.
This still isn't a full explanation, but it rules out most of the malarkey generated so far on this thread.
In the freight world the tolerances for allowable wheel profile - and the reality that out-of-spec wheels can travel some ways before getting caught - mean that you would never design a system that relied heavily on the wheels having a particular flange width. So I can't really envision exactly what the problem is. It's not really clear to me from the article whether this is actually a safety issue (trains could fall off the tracks) or an economic issue (frogs have an unacceptably short life).
The originally posted 'article' left much to one's imagination.
Folks, in the time you spend writing wild and crazy speculation on the Trains forum, you could have used Google to find the following article:
Not that surprising. Transit vs. common carrier freight railroading.
(FRA rules everywhere and FTA almost none; AREMA vs ASCE ; Federal rules vs State Regulation; proven technology & testing vs. seat of the pants new....and so on)... The "anything goes" transit guys got bitten this time and fortunately nobody got hurt.
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