'ZIg-Zag' welding on rail face surface - what was it for?

[Rail-Online]

Hi,

The attached was taken in 1959 at Barbican and I first saw this in the early 1970s in Lincolnshire and was told it was for train detection purposes but I was very doubtful even then!

 

What was it for?

 

Tony

[uax6]

Its steel wire (later stainless steel wire) welded to the railhead on tracks that are little used to ensure that the track circuit operated correctly. It gives a much more focused area of contact with the wheel tread than a rusty railhead does.

 

Andy G

[eastwestdivide]

Detection is what I’d always understood it to be. In your photo it looks like a little-used connection, but it’s also to be found (think it’s still there) at the buffer stop ends of the heavily-used north end bay platforms at Sheffield. Use to create quite a judder as a pacer came to a halt. 

Edited January 7, 2022 by eastwestdivide
Buffer ends

[Tom Burnham]

I've been told that it was to ensure that vehicles were detected by track circuits even if the rail head became very rusty or dirty. Most often seen at the end of platform dead end lines, near the buffers, in my observation.

[iands]

To ensure track circuits will operate when "shorted" by train wheels. Usually found on infrequently used sections of line where a build up of rust/muck would otherwise make the correct operation of tack circuits unreliable. Used in the bay platforms at York Station and no doubt plenty of other locations. 

Edited January 7, 2022 by iands
smelling pistake. And to agree with other post.

[MossdaleNGauge]

Correct, used to ensure the track circuit operates correctly on lightly used rails that get a covering of rust due to lack of use. A cheaper manual alternative was to spread a paste of sand and small stainless steel balls on to the rails.

[iands]

4 minutes ago, MossdaleNGauge said:

Correct, used to ensure the track circuit operates correctly on lightly used rails that get a covering of rust due to lack of use. A cheaper manual alternative was to spread a paste of sand and small stainless steel balls on to the rails.

And replaced the "depression bar" operated by wheel flanges. 

[BR traction instructor]

An apparently unintentional advantage stemmed from idling diesel units/locos standing on the stops at terminal stations, dripping oil/fuel etc onto the rail surfaces. The next train to arrive once the previous occupant had departed would likely have some low speed wheel slide on the contaminated rail surface…the zig zag weld helped with stopping, even though you wouldn’t normally drive onto it…the noise of running onto the weld under an overall roof certainly grabbed everyone’s attention.

 

BeRTIe

Edited January 7, 2022 by BR traction instructor

[eastwestdivide]

14 minutes ago, BR traction instructor said:

even though you wouldn’t normally drive onto it

Interesting. They always drove onto it at Sheffield (in my experience as a very regular passenger there over the last 20 odd years). But yes, noisy!

[BR traction instructor]

A station such as Manchester Piccadilly was much more enclosed and the sound therefore more contained, echos greater etc.

 

BeRTIe

[31A]

20 minutes ago, eastwestdivide said:

Interesting. They always drove onto it at Sheffield (in my experience as a very regular passenger there over the last 20 odd years). But yes, noisy!

 

Always drive onto it in York station as well - the sound of a Harrogate train arriving in Platform 8 is quite distinctive!

[Ncarter2]

It’s also a pain for rail testing and defect management. 
Several locations I know of have been renewed and the zig-zag has not been replaced. 
 

[BR traction instructor]

TCAs (track circuit actuators) built into the modern units may have reduced the need for it.

 

BeRTIe

[Mol_PMB]

In terminal platforms the main risk was a single loco standing at the bufferstops being lost by the track circuit as discussed above. Longer trains would extend onto the shiny part of the rails.

It’s now extremely rare for a single loco to stand by the stops, because trains are pretty much all fixed formation. Rugby thunderbirds may be a rare example.

TCAs also help to solve the problem, and of course there is increasing use of axlecounters instead of track circuits. 

Localised welding on the rails can introduce flaws and cracks, while the very small wheel/rail contact on a freshly made zig-zag can also damage the wheels.

 

[BR traction instructor]

Locos had the weight per axle to overcome contaminated rail surfaces and ensure that the track circuit was operated. Lightweight units, especially ones without tread brakes to clean wheel running surfaces would have been a much bigger culprit.

 

153s were amongst the first units fitted with TCAs…single car, tread brakes (apologies), limited wheels to activate track circuits, lightweight etc etc

 

03s were an exception amongst locos and needed a match wagon attached to them to ensure that track circuits were activated e.g. the Norwich allocated one’s working around the station.

 

BeRTIe

Edited January 8, 2022 by BR traction instructor

[iands]

1 hour ago, BR traction instructor said:

 

03s were an exception amongst locos and needed a match wagon attached to them to ensure that track circuits were activated e.g. the Norwich allocated one’s working around the station.

 

BeRTIe

The match truck/wagon with the 03s were for a slightly different reason, well at York anyway. Because the 03s have a relatively short wheelbase, the match truck/wagon effectively lengthened the 03s wheelbase to ensure the 03 didn't momentarily "dissappear" off the panel when moving about the station, particularly across complex S&C. 

[BR traction instructor]

08s were a similar length but I don’t recall them having a match wagon when on station pilot duties.

 

BeRTIe

[iands]

35 minutes ago, BR traction instructor said:

08s were a similar length but I don’t recall them having a match wagon when on station pilot duties.

 

BeRTIe

The difference in wheelbase lengths between an 03 and 08 is 2' 6". Doesn't sound much, but the 03s would occasionally dissappear off the panel if they didn't have the match truck/wagon - also referred to as a "runner". 

[hexagon789]

3 hours ago, BR traction instructor said:

pad brakes acting on discs

153s have treads...

[The Pilotman]

Welded zigzags were also to be found on the exit road at Didcot Power Station for a time. It was an attempt to reduce the number of point failures at Foxhall Junction caused by the slides becoming clogged with coal dust falling from the discharged wagons. The idea was that any loose dust would be dislodged as the train passed over the zigzags before reaching the junction points. I don’t know if this was tried anywhere else. 

[Michael Hodgson]

I suppose that's the ropey trackwork in NCB collieries served the same purpose.  

[Davexoc]

They are om the DC lines platforms (at Least) at Euston, so hardly lightly used, or prone to diesel deposits.

[Michael Hodgson]

25 minutes ago, Davexoc said:

They are om the DC lines platforms (at Least) at Euston, so hardly lightly used, or prone to diesel deposits.

Only on the running rails, or the 3rd rail too?

[The Stationmaster]

18 hours ago, iands said:

And replaced the "depression bar" operated by wheel flanges. 

As it did at York (where there were also VOL (Vehicle On Line) switches for the bay platforms)

[Davexoc]

43 minutes ago, Michael Hodgson said:

Only on the running rails, or the 3rd rail too?

 

Just the running rails. Don't what era they first appeared, 501, 313, or 378, but it makes the new 710s rattle....