New ideas for rail expansion joint

[roman]

EDIT: please, see my next post below for fixes of basic flaws of the suggested in this post ideas.

Because continuous welded rails are more expensive to lay than ordinary jointed track and can result in rail buckling during extreme summer heat, why not use some of joining techniques, listed below.
1) First, why not use more often the diagonal expansion joint, shown on the picture below (from Wikipedia)?

2) My idea for an "overpass" rail.
For this we need a double sided wheel set like this:

This is how the track looks from the top:

And the side view of the track joint:

Of course, the climb of the "overpass" rail doesn't have to be so steep and high as in the picture. It's just for the illustration of the concept.
It seems to me, that the double sided wheel set, shown on the picture above, won't cause any trouble at railroad switches, as the inner side of the wheel is at the same level as the outer (usually running) side of the wheel.
The extra weight of the wheel set (due to the addition of the inner side), probably won't cause too much extra energy loss (if any at all).

3) Another simple idea about an "overpass plate cover" of a rail joint:

Certainly, the plate is properly attached to the joint and not just falling off the rails.

So, what do you think of it?

P.S.: Just asking and suggesting. Not saying the "final truth" and "everyone must implement this". Nothing of the sort. If you think the ideas are not viable, just say why and that's all.
Please, reply if anyone has any interest in this

 

[John Webb]

1. Changing the wheel sets would be extremely expensive when compared to your first suggestion of using more 'Breather' joints.
2. A lot more rotating mass hammering the track.
3. Some newer pointworks have check rails higher than the rail the wheel runs on - hence the ban on the 2-10-0 9Fs running on the main line network as has been mentioned elsewhere in the Forum. This would cause serious problems with your revised wheelsets.

John Webb

 

[Elecman]

The answer may be to stress to a higher stress free temperature than that used at present, but the drawback to tgat of course is the risk of more weld fractures in colder weather. More Breathers are not really an answer as they introduce more maintenance requirement.

 

[Ploughman]

The introduction of more Expansion joints would probably worsen the situation.

What may be better to do is to re assess what the Stress Free Temperature of the rail should be.
Should the figure be revised upwards from 27 deg C to 28 or more?

 

[roman]

Thanks everybody for the replies!
Some time after posting I found some basic flaws in my suggestions, but couldn't edit them because the post was awaiting for moderation. So, here are the fixes.

First, because the inner side of the double side wheel set is of conical shape, that is pointed inside the track, this construction will always be trying to put a train OFF the track and destabilize it, while a conventional outer conical surface is pointed outside the track and always tries to put a train INSIDE the track and stabilize it. There may be two solutions for it.
The first solution is to have doubled wheels, that even looks weird:

This will require modification of all joints, that is very bad.
The second solution is to use a flat inner surface:

This at least will not be trying to put a train off the track. But this will also cause a problem with the check rails, that are higher than the wheel running rails. So, the application of this may be only on new dedicated lines with no compatibility with other lines (for example, subway or LRT lines).

So, if we want compatibility, we should leave a conventional wheel set. In this case, we might do joints like this:

And the side view:

This "overpass" rail should be of extra hard steel as it's supposed to be much narrower than a conventional rail. But this idea is, actually, very close to the "breather" joint idea.

You rightly mentioned that it more breather joints may result in more maintenance requirements. But it still seems better than "clickety-clack" track. The main market may be in countries with huge temperature differences.
The breather joint may be a little modified (non-diagonal rail ends) to allow even easier installation:

To allow a smooth transition from one rail to another the height of the rail on the joint part should be gradually decreased towards the end of the rail:

The rails should be manufactured like this:
Gradual decrease of rail height on the joint part (side view):

Side view with explanations:

So, probably, the best option of all the ideas may be to use "breather" joints or modified "breather" joints.

Finally, why am I concerned about rail joints? As I've explained welded rails may be a challenge in places where there are huge differences in temperatures throughout a year. And a jointed "clickety-clack" track is usually considered unsuitable for busy lines, because of it's instability if often used.

Rail buckling or weld breaks may not be a big issue in the UK with it's relatively mild climate, but for the countries with huge differences in temperatures throughout a year it may be very important. And, probably, "breather" joints might be a less costly and easier solution than welded rails.

 

[Joseph_Locke]

The biggest flaw in your proposals is that you are trying to solve problems that doesn't really exist by introducing a new set of problems, some of which have already been tried and abandoned.

Any point of mechanical weakness will be subject to enhanced maintenance compared with plain rail.

Ordinary fishplated joints and adjustment switches are both points of mechanical weakness and require enhanced maintenance compared with plain rail.

Whilst CWR is initially more expensive to lay (only marginally) and slightly more costly to maintain in terms of replacing rails, post-1974 concast rail has a very low rate of rail defects and CWR does not need an army of patrollers, nut tighteners, joint straighteners, joint regulators and plate oilers; the whole life cost difference is pretty infinitesimal.

Improvements in Thermit welding practice have virtually eliminated weld failures and the availability of mobile FBW plant means that much alumino-thermic rail welding can be eliminated.

Poorly maintained jointed track buckles just as much as badly maintained CWR.

High ride quality on CWR is much easier to maintain than on jointed.

The railway did have so-called LWR, which were 200y rails joined using adjustment switches - we stopped doing it 30 years ago because it isn't a very good idea, overall, for the reasons given above.

 

[ac6000cw]

Because continuous welded rails are more expensive to lay than ordinary jointed track and can result in rail buckling during extreme summer heat

Is CWR really more expensive to lay than jointed track (using modern mechanised methods)?

Even if it is, the lower maintenance cost of CWR (due to not having to inspect and maintain the joints) is a major reason for preferring it.

As far as I'm aware, railways use CWR in many parts of the world with much more extreme temperature variations than in the UK, both seasonally and day/night variations. I guess they just design the track structure to deal with the higher stresses (different rail sections and steel specification, sleeper spacing, ballast shoulder depth etc.). At worst I guess they might have to re-stress the track seasonally. And jointed track will buckle and fracture if not laid and maintained correctly - these aren't new problems that arrived with CWR.

 

[roman]

Ok, thanks again!

Before closing the topic, it's worth mentioning that nowadays rail joints could be maintained automatically by using automated joints maintenance vehicles (they could be created, it's not a big problem today).

But I get it. Hence today's CWR technology is cost-efficient and so stable and reliable, that during extreme summer heat it doesn't require speed restrictions, and doesn't cause delays and buckling, there is no reason to invent some kind of a new rail joint type.

Thanks everyone for the discussion!

 

[DarloRich]

what problem are we trying to fix here?

Getting the usual wheelsets can be hard enough in the volumes we buy in this country - getting special double faced types would be fun!

 

[randyrippley]

Doubling the wheels would more or less double the unsprung mass bouncing on the track. Doubt if the track would survive it for long. You'd get fracturing of the rail surface due to the impact blows. Remember what the class 86/0 did to the track? Imagine that, tenfold
Besides which, on a power bogie is there room to widen the wheels?

 

[L&Y Robert]

Trams run on their flanges through crossings sometimes. I have seen tramway crossings where the flange-way is gently - very gently - ramped so that the wheel tread is not in contact with the rail head at the point of the crossing. Could that be a simple answer to the double wheelset/ramped subsidiary rail idea?

However, I watched a thermit weld being done from start to finish (Haddenham and Thame Parkway it was), and was impressed by the care the technician took when finishing the join. He took great pains to level the rail for a couple of metres on each side of his weld, then ground the weld smooth on the head and on the flange-face; next checked it with the longest streight-edge I have ever seen, fussed about with a finer grinding tool, and at last decided it would do. Even so, whenever I travel over this bit of track I note the very slight 'rumble' at that point (of course I know just where to expect it). So I can't see that any of the "remedies" discussed up the thread would result in a smooth ride over the joint, and especially not at any speed.

I note that they paint the rails white in Italy, to reflect a bit of the sun's heat I guess. Have we tried a rail-cooling water-spray train? Yes, pathing etc.

 

[rebmcr]

I note that they paint the rails white in Italy, to reflect a bit of the sun's heat I guess. Have we tried a rail-cooling water-spray train? Yes, pathing etc.

We have a lot of white paint too, especially around pointwork.

A train would not make much difference at all, but there have been trials of sprinkler-type fixed installations. I don't recall them being very successful.

 

[ac6000cw]

Trams run on their flanges through crossings sometimes. I have seen tramway crossings where the flange-way is gently - very gently - ramped so that the wheel tread is not in contact with the rail head at the point of the crossing. Could that be a simple answer to the double wheelset/ramped subsidiary rail idea?

Flange-bearing crossings also exist on heavy rail systems e.g. in the USA. See https://en.wikipedia.org/wiki/Flange-bearing_frog

 

[gallafent]

The “overpass rail” approach is used in certain specialised situations, for example with moving bridges — they call it a “rider rail”:

http://www.cmi-promex.com/products/rail/ridex_miter_rails