If we go to a world where engineers big-hole monster consists every time they see trespassers or vehicles encroaching on crossings, I suspect you’ll see more…
I suspect there might also be a connection with flats; I don’t know how carefully wheels are NDT-tested when the flats are trued out.
If you look at the metallurgy in crack propagation you’ll get an idea of how difficult it might be to detect this particular thing with a running inspection: I think it’s a bit like a collar-button abscess with the real damage invisible in a volume within the wheel difficult to ‘visualize’ on ultrasonic scan.
I’d at least look at the contemporary history of brakeshoe composition; it may be that some formulations intended to outgas less (and hence have lower tendency to runaway fade) might spot-overheat damaged tread adjacent to the ‘depressed’ rail/wheel contact zone.
I assume this wheel breaking problem is simply unsolvable because it is wrapped up in so many possible causes, and it is also part of a vast standardization of wheel design practice. The need to change that vast standard places limits on how much change is possible.
When you consider how much research has been done on this wheel breakage problem in the last 30 years, and the fact that the cause is still not clearly understood, let alone the discovery of a remedy; and considering all the unanswered questions that this research has raised, a solution timeline seems indefinite at best. It is dizzying to consider all of the possible combinations of problem and solution that are raised in the link here in the original post. Each little twist and turn of those possibilities could require millions of dollars worth of research over years of time to even place it into the proper perspective of the overall goal of eliminating the wheel breakage problem.
One obvious solution is for U.S. practice to covert from single-wear wheels to multiple-wear wheels. Single-wear wheels are “run-until-failure”, with only one wheel truing operation allowed during the wheel life. The rest of the world uses Multiple-wear wheels which are intended to be re-trued on a regular basis. This extends wheel life because the wheel is maintained in optimum condition.
Because single-wear wheels are only re-trued once if at all, they accumulate surface damage such as micro cracking, flat spots, and stress development. These defects are able to develop as paths to sudden failure su
This would follow closely the “Pinto Principle,” wherein the manufacturer decided it was cheaper to pay off lawsuits than it was to actually fix the problem.
Without a detailed cost analysis, though, we may never know.
The only thing multiple wear wheels would accomplish is to increase the tare weight of a car by several hundred to 1K pounds, thus decreasing the amount of freight that the car can haul at capacity each trip. Germany has 2500 foot trains; USA is approaching 20K foot trains as normal.
It is not apples and oranges. Multiple wear wheels periodically have their treads re-trued in order to reestablish the proper tread/flange profile and eliminate surface defects such as flat spots, cracks, and residual stress that are induced as the wheels run in service. It is all of those defects that accelerate tread deterioration and causes the wheel to be cond
Single-wear wheels are “run-until-failure”, with only one wheel truing operation allowed during the wheel life. The rest of the world uses Multiple-wear wheels which are intended to be re-trued on a regular basis.
Changing the wheel standards from single-wear to multiple-wear wheels would definitely be a sweeping change.
That would explain why one hears so many flat-spot wheels on our freight compared to ones in Germany.
Apples and Oranges
The only thing multiple wear wheels would accomplish is to increase the tare weight of a car by several hundred to 1K pounds, thus decreasing the amount of freight that the car can haul at capacity each trip. Germany has 2500 foot trains; USA is approaching 20K foot trains as normal.
It is not apples and oranges. Multiple wear wheels periodically have their treads re-trued in order to reestablish the proper tread/flange profile and eliminate surface defects such as flat spots, cracks, and residual stress that are induced as the wheels run in service. It is all of those defects that accelerate tread deterioration and causes the
Fig and prunes [since this is largely a forum for the elderly [:-^]]. Why would length of train result in more flat spots that continue uncorrected? Excessively long and heavy, slow trains running with “precision” are all part of a corporate policy of short-term profits and looting.
Whales and flowerpots (to invoke infinite improbability).
Multiwear wheels are so because they are cast with different metallurgy and treatment to have a thicker rim, which is where the extra tare weight, rotational moment, etc. live. As Balt implies, this adds up to an enormous aggregate mass penalty (albeit a variable one as some percentage of the wheels presumably wear down to the condemnation limit) and very little time or effort would be saved in turning them in three-piece trucks in situ with an underfloor-lathe setup vs. just changing out wheelsets and bearings and then ‘remanufacturing’ in more-or-less interchangeable single-life units.
Now I among others have argued that this would be different if wheels with extended ‘wear life’ matching that of modern AP bearings with M-942 lubrication were used – at present perfectly-serviceable bearings with long prospective safe wear life are destroyed in order to press condemned single-wear wheels on and off. Something I have never gotten good data on (and would like to see, if it exists in proper form) is whether running flat at various intensity short of the actual time of reprogoling in fact does damage the bearing in some way that increases risk of far more catastrophic failure than a rim breakage would cause.
I’m surprised no one has brought up the arguments pro and con about how the wheels handle high braking heat. In interchange service, braking has to be scaled to the ‘least common denominator’ of wear limit anyway, so the discussion usually turns to induced-crack propagation in the absence of widespread effective field NDT testing of wheels for induced or SCC damage. There has been plenty of discussion whether a ‘magic wear rate’ exists for multiple-wear wheels but I confess I’m far more concerned with “mistakes of assumption” in wheels than in rails, which can be and are readily and repeatedly tested analytically for stress-raising issu
According to the link in the top post, the majority of world railroads use Multiple-wear wheels, whereas the U.S. uses Single-wear wheels. Also, the report in the link says that Rio Tinto, which runs Multiple-wear wheels at higher wheel loading than U.S. practice, has no wheel failures. So their example offers proof that a wheel re-truing program would eliminate the wheel breakage plaguing U.S. practice.
The periodic wheel re-truing associated with Multiple-wear wheels, as practiced by Rio Tinto, would indeed require new infrastructure and operating specialists for application to U.S. railroads. I am sure the Multiple-wear wheels are more expensive as well.
It would be nice to find references to the wheel re-truing practices used by Rio Tinto, as it might be a good example of what could be applied to U.S. practice. Maybe the application of the wheel re-truing, as applied to U.S. practice could be farmed out to independent contractor service companies, such as is done with railroad wreck services.
There is definitely added cost to a wheel re-truing program, but it also comes with added benefit. However, the cost/benefit is a gamble with odds likely not agreed on.
Just one Lac Megantic style oil train wreck caused by a wheel failure will have the court studying this 20-30 years of wheel research that clearly identified the problem, but never solved it. That would be a financial risk, but the larger systemic risk would be to trigger the government into mandating new wheel standards.
We need a cost analysis of the two types of wheels - initial cost, and the cost of maintenance over the life of the wheel. Even the relative scrap value should be figured in.
There have been wrecks caused by wheel failures, which would tend to provide the cost of such incidents.
Then we compare. The single wear wheel may be cheaper in the long run. Or not.
As the FRA report says, the payoff for solving this wheel problem is not just longer lasting wheels, but also includes potential savings in rail wear and the cost of derailments.
I suspect that the existing wheel design has been carefully developed with lots of little tweaks to get it just adequate to do the job, but nothing more. The design includes not only the physical shape of the wheel, but also many factors of manufacturing process, including metallurgy, hardness, malleability, etc. And these characteristics are not necessarily consistent throughout the wheel, but rather may be customized for applying to various features of the wheel. So with all of this tweaking, you end up with a lot of variables cooked up just the right way to work their magic of successful wheels.
This objective would be difficult enough if it were locked in place and waiting for the miracle of success. But the objective is not locked in place. It is shifting with other changes such as higher axle loading, rail grinding, train operations, and all of the metallurgical factors affecting rail just as they affect the wheels.
Suddenly, for some unknown reason, the magic formula for the wheel has become not quite adequate. And because the formula or design is so intricately complex with all of the tweaking, it poses so many theories of the cause of the trouble and possible remedies that the chance of solving the problem with just another little tweak is nearly impossible. Yet nobody wants to go beyond the smallest possible remedy because doing so would waste money.
[quote user=“Euclid”]
As the FRA report says, the payoff for solving this wheel problem is not just longer lasting wheels, but also includes potential savings in rail wear and the cost of derailments.
I suspect that the existing wheel design has been carefully developed with lots of little tweaks to get it just adequate to do the job, but nothing more. The design includes not only the physical shape of the wheel, but also many factors of manufacturing process, including metallurgy, hardness, malleability, etc. And these characteristics are not necessarily consistent throughout the wheel, but rather may be customized for applying to various features of the wheel. So with all of this tweaking, you end up with a lot of variables cooked up just the right way to work their magic of successful wheels.
This objective would be difficult enough if it were locked in place and waiting for the miracle of success. But the objective is not locked in place. It is shifting with other changes such as higher axle loading, rail grinding, train operations, and all of the metallurgical factors affecting rail just as they affect the wheels.
Suddenly, for some unknown reason, the magic formula for the wheel has become not quite adequate. And because the formula or design is so intricately complex with all of the tweaking, it poses so many theories of the cause of the trouble and possible remedies that the chance of solving the problem with just another little tweak is nearly impossible. Yet nobody wants to go beyond the s
There is still hope. This is only Wheel Failure Investigation Program: Phase I. They have not yet solved the problem, but they do at least consider the method used by Rio Tinto that eliminates the problem for them.
Investigating the feasibility of using the Rio Tinto program to eliminate U.S. railroad wheel failures is an action item of this 5-year study by the FRA.
It is interesting that the report cites roadbed resiliency as being a possible factor explaining why wheel failures occur more frequently in the west than in the east. The correlation is that western railroads use more concrete ties versus wood ties, which are more common on eastern railroads. Concrete ties are less resilient than wood ties.
Another resiliency factor is the season. In winter, the ballast is frozen, so it is less resilient than in summer. This too correlates with wheel failures, which are more numerous in winter and spring than in summer and fall.
FRA report of tests of acoustical warning devices. Guess that includes loco horns. This report says phase 1. That may be the reason that the Acela-2s being tested have the regular horn and the European style horn that we often hear in various U tube recordings ?
That sounds like they are developing the kind of warning sound that would best alert a distracted person such as we discussed regarding the CSX Ivy City accident that killed the two CSX employees. That accident happened in a unique situation where two trains were sounding horn warnings to them at the same time, but they were facing one train approaching them and apparently believed the two train warnings they were hearing were coming from just the train they saw approaching them. They were clear of that train, but were fouling the track of the other train which was approaching from behind them. If the two trains were sounding radically different warning sounds, there would have been a better chance of the two victims distinguishing one train from the other, and thus realize there was a second train coming up behind them.
See my comments in the other thread [“Harrison’s thread”], regarding what the Canadians now mandate as their horn design. I find it strange that research conducted as late as 2019 does not mention this.
It appears to me that the extra ‘two bells’ of the Canadian emergency modification could easily be adapted to produce the effects of options #9 and #10 in the FRA study (the two they identified as the most promising alternatives) as well as some of the proposed higher-harmonic amplification or high-speed overmodulation that were discussed. As far as I can see these would not add materially to the cost of the already-in-production Canadian horns.