Steam locos running on OHLE lines

[Harlesden]

I have always assumed that the steam coming from a locomotive's chimney must be rather hot - as the same way as the steam from a kettle in the process of coming to the boil.
Have any tests ever been carried out to ascertain whether or not a running steam locomotive has any adverse effect on the OHLE cables underneath which it runs?
I may be wrong but I have the impression that most steam specials that touch London either leave from or arrive at King's Cross. As the OHLE on the ECML is rather a poor build to begin with - done on the cheap -is it possible that the occasional steam locomotive using the ECML has a weakening effect on an already fragile structure?

 

[sprinterguy]

In the closing days of steam on the London Midland Region, locomotives were given a yellow stripe across the cabside to denote that they were not to operate under the wires south of Crewe on the WCML. Strangely enough, at least one, Scottish allocated I believe, Gresley A4 was also given this treatment - Possibly "Kingfisher" (EDIT: It was actually 60027 "Merlin" that I was thinking of, as seen here: http://www.railbrit.co.uk/__cache/images/32000/32945.jpg).

In general, I think that it is the moisture content in the steam, rather than heat, that causes problems with the overhead electrics, as the vapour causes the wires to short out.

I may be wrong, and will surely be corrected if so, but the passage of steam locomotives under OHLE at any location (Except terminus stations or popular railtour destinations, where the locos will sit chuffing away under the wires for a considerable period of time) is so infrequent that it probably has a negligible effect on the condition of the overheads compared to the daily wear and tear exerted on them by the passage of pantographs.

 

[Southwest]

As the OHLE on the ECML is rather a poor build to begin with - done on the cheap -is it possible that the occasional steam locomotive using the ECML has a weakening effect on an already fragile structure?

Is this a known fact or are you just speculating as to the quality of the OHL?

 

[HSTEd]

After the completion of Steam Phase out the designs for the OLE meant for use on future projects were changed to replace phosphor bronze fittings with galvanised steel ones.

This was to reduce cost since the atmosphere the designs experience today are far less corrosive than that which was experienced before the phase out.

EDIT:

And why do people obsess over the "low quality" of the ECML equipment?
If you actually crunch the numbers it does not suffer significantly greater numbers of failures than the equipment on the WCML.

 

[Monty]

Is this a known fact or are you just speculating as to the quality of the OHL?

The ECML electrification was very much done on the cheap, to my knowledge the spacings of the catenary pylons are a lot wider than that on the WCML. So it's not the wires persay or the equipment that is the problem it's the pylons.

 

[Harlesden]

Thanks for the responses, gentlemen. It seems Monty has answered Southwest's inquiry.
I actually have no idea how far apart the pylons actually are, but it must be must cheaper to erect 70 pylons that are 200 yards apart than to erect 140 that are 100 yards apart

 

[sprinterguy]

I actually have no idea how far apart the pylons actually are, but it must be must cheaper to erect 70 pylons that are 200 yards apart than to erect 140 that are 100 yards apart

The OHLE stanchions (The cantilever type, certainly) on the ECML are spaced 45 - 50 metres apart as far as I know, though I'm not sure of the precise distance. I'm not sure whether there are any differences in the spacing of the wider headspan type catenary found elsewhere on the ECML.

 

[O L Leigh]

The problem with steam under the overheads has nothing to do with the moisture content, otherwise we would never be able to run in the fog or when it was raining or through tunnels that are perpetually wet.

The biggest issue is actually to do with the strength of the chimney blast rather it's moisture or carbon content (in the form of soot). Drivers of steam engines are required to stop with the chimney away from any OLE structures so that the force of the blast is not concentrated onto the structure. The blast can also cause sway in the overheads themselves that can result in the juice arcing across gaps.

Steam specials regularly use Liverpool Street too, so the notion that they must use Kings Cross is bunkum. However there are restrictions on platforming and routing them. Even if they are going to head down the WA route towards Cambridge or Ely they must run via Stratford and not Hackney due to the clearances in the tunnels towards Clapton.

**EDIT**

On the perennial topic of the ECML electrification, cheaper does not necessarily equate to worse. The structures on the WCML are massively over-engineered and date from a time when electrification at 25kV AC for mainline railways was still experimental. Two decades of experience together with knowledge gained from overseas operators have shown that structures as huge as these are not necessary. Yes the ECML could have been wired to the same specification as the WCML using the same types of structures, but the cost would have been prohibitive and would have made the difference between it going ahead or being canned. And for what advantage? There are still dewirements on the 1960s electrification schemes together with weather-related speed restrictions just as there are on the ECML and other newer schemes.

O L Leigh

 

[blackfive460]

In the closing days of steam on the London Midland Region, locomotives were given a yellow stripe across the cabside to denote that they were not to operate under the wires south of Crewe on the WCML.

That was due to insufficient overhead clearances and only applied to certain classes.

 

[wilsontown]

I seem to remember some youtube footage of a steam railtour causing arcing of the OHLE at Liverpool Street..ah yes, here it is...

http://www.youtube.com/watch?v=vQTinmPjS_o

 

[Teaboy1]

That was a pretty impressive -pop- hard to detect exactly where it flashed-over to but I think its around the dome area as the sparks then fall over the fire-box /ash-pan area ... and its immediately after a minor slip.....!

Does look like the whole atmosphere is about 110% humidity so perfect flash-over scenario conditions. Must have done some damage to copperwork IMHO as those sparks look substantial. Wont endear steam to Notwork Rail either

 

[Brystar35]

About electrification over here in the states the Pennsylvania railroad had electrified its mainline with overhead wires which look massive as heck, the ecml and wcml caternies look smaller compared to the pennsy which Amtrak upgraded and currently uses.

 

[DXMachina]

Wasnt the Penn system at 11000v though? lower voltage catenary is always thicker - higher currents require thicker conductors - which in turn require heavier supports

The higher the voltage, the smaller the diameter of the cable required for the same equivalent power.

 

[Brystar35]

Ohh so that's why there like that I can put up pictures to show how they are? I wonder what about third rail does that has an Effect on steam locomotives?

 

[Bedpan]

There was a ban on steam locomotives operating over third rail lines for some years after steam was re-introduced in the early/mid 1970s. I think that this was more to do with the effect of the live rail on people trespassing and walking across the lines to watch the locomotive go past than on the locomotive itself though. In those days it used to be quite normal to have people standing all over the place, particularly at places where the train stopped/started.

 

[snowball]

The structures on the WCML are massively over-engineered and date from a time when electrification at 25kV AC for mainline railways was still experimental.

I thought they much lighter on the early 1970s sections north of Weaver Junction than on the 1960s (or 50s) ones?

 

[Mr Sam]

thats brilliant

I seem to remember some youtube footage of a steam railtour causing arcing of the OHLE at Liverpool Street..ah yes, here it is...

http://www.youtube.com/watch?v=vQTinmPjS_o

 

[themiller]

Pure water is not electrically conductive. The likely reason for the flashover is more to do with the exhausted steam creating a greater level of draught over the fire-bed which would draw coal dust up through the funnel. Carbon is a very good conductor of electricity so, as it blew up toward the overhead, it would have allowed current to pass from 25kV, down through the loco and rails to earth at 0V.

 

[snowball]

When they were planning the first 25kV electrification they had to decide what the minimum clearance requirements had to be, so they did experiments in a tunnel with a steam locomotive to create conditions likely to cause a flashover.