Transilien
Member
What are the main weaknesses of this design that made it have to be replaced? Can Mark 1 OHLE handle 125 mph running or is this impossible?
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Why did Mark 1 OHLE need to be replaced under the the WCML modernisation?
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GRALISTAIR
Established Member
Well it was done in the 1950s and 1960s , so it was quite old anyway.
Transilien
Member
Was it of a less quality then more recent Mark 3 OHLE which is reaching the same age now as the Mark 1 OHLE used on the West Coast at the time of the modernisation? Apart from the replacement of headspans there doesn't seem to be much of a drive to replace that type.
I've heard it said that the MK1 would've been suitable for 125mph (deep register arms, quality of components, robustness) but I'm sure it would have needed higher tensioning. MK3 was largely replaced on the WCML by UK1 to facilitate higher speeds as it was designed for 110mph. Having said that, for sheer elegance and aesthetics I contend that MK3 (especially 3a) can't be beat.
OHLE_worker
New Member
All overhead line equipment has a lifespan, which is one of the reasons why the MK1 OHLE was eventually replaced. As noted, the MK1 equipment was installed in the 1950s and 60s. While components like the structures and registration assemblies could still be functional, the contact wire would have needed replacement due to wear from the pantograph. Rather than just replacing the contact wire, it made sense to upgrade the entire system at once. This approach avoided the need to revisit and replace other aging components 20 years later, which would have been beyond their expected lifespan by then.
Carrying out the upgrades requires track access, leading to service disruptions and fewer trains running, which negatively impacts revenue for the Train Operating Companies (TOCs). Therefore, replacing both the equipment and the contact wire simultaneously is an efficient solution, effectively “killing two birds with one stone.”
Another reason for replacing MK1 equipment is that it was originally designed for speeds up to 100 mph, which required lower tension in the overhead wires than what is used today. Additionally, many components of MK1 equipment were made from copper, which is expensive. Modern systems, such as MK3, UK1, and Series 1 & 2, use components made from steel, which is more cost-effective. In fact, many of the components used in modern equipment are redesigned versions of those from the MK1 system.
The signaling systems also posed a challenge. MK1 signaling systems were not designed to handle the higher traffic densities and speeds of modern rail operations. Today’s high-speed trains require more advanced signaling systems, often involving upgraded trackside technology.
Finally, MK1 rolling stock, though robust, was not built for sustained operations at 125 mph. Modern trains operating at these speeds are aerodynamically optimized and equipped with advanced braking systems, suspension, and other technologies to ensure safety and comfort.
In summary, MK1 equipment is generally unsuitable for trains traveling at 125 mph without significant upgrades. For safe and reliable operation at these speeds, both the OLE and signaling systems need to be modernized. which is why, most of the UK’s electrified routes that accommodate high-speed trains have been upgraded from their original MK1 specifications to more contemporary standards.
Hope this helps.
Carrying out the upgrades requires track access, leading to service disruptions and fewer trains running, which negatively impacts revenue for the Train Operating Companies (TOCs). Therefore, replacing both the equipment and the contact wire simultaneously is an efficient solution, effectively “killing two birds with one stone.”
Another reason for replacing MK1 equipment is that it was originally designed for speeds up to 100 mph, which required lower tension in the overhead wires than what is used today. Additionally, many components of MK1 equipment were made from copper, which is expensive. Modern systems, such as MK3, UK1, and Series 1 & 2, use components made from steel, which is more cost-effective. In fact, many of the components used in modern equipment are redesigned versions of those from the MK1 system.
The signaling systems also posed a challenge. MK1 signaling systems were not designed to handle the higher traffic densities and speeds of modern rail operations. Today’s high-speed trains require more advanced signaling systems, often involving upgraded trackside technology.
Finally, MK1 rolling stock, though robust, was not built for sustained operations at 125 mph. Modern trains operating at these speeds are aerodynamically optimized and equipped with advanced braking systems, suspension, and other technologies to ensure safety and comfort.
In summary, MK1 equipment is generally unsuitable for trains traveling at 125 mph without significant upgrades. For safe and reliable operation at these speeds, both the OLE and signaling systems need to be modernized. which is why, most of the UK’s electrified routes that accommodate high-speed trains have been upgraded from their original MK1 specifications to more contemporary standards.
Hope this helps.
GRALISTAIR
Established Member
Wow - thanks for you reply and welcome to the forum - your first post I see.
Transilien
Member
Thanks for the detailed response! It’s really helpful.
== Doublepost prevention - post automatically merged: ==
What's the difference between mark 3a and 3b OHLE? (Sorry this is rather off topic).
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edwin_m
Veteran Member
This wear will depend, among other things, on the number of pantograph passes experienced, but the section north of Weaver Junction has seen far fewer electric trains per hour (and therefore per year) than further south. So it probably has some years of life remaining.
GRALISTAIR
Established Member
And was done at a later date too.
3a tended to be less 'formal' - the top cantilever to some extent and the registration cantilever almost without fail - tended to be at an angle just off the horizontal which (to me) made it look more dynamic as if it were stretching to reach the wires and having fun. When 3b came along it reverted to a more horizontal, more vanilla look. (nb: these are not necessarily engineering terms
). There are other minor detail differences of course and it kept evolving.superkev
Established Member
I believe the number of pantographs that could be raised was an issue with early designs. Wasnt the spec. for the heavily engineered GWML scheme to support 2 pans upto 140mph (eg 2 x 5 car 800s).
The original APT had all traction centralised so only one pan was needed.
The original TGVs had 25kv cables running along the roofs between the end power cars to avoid using 2 pans. This caused some consternation with the UK safety industry at the time but has since become the norm.
K
The original APT had all traction centralised so only one pan was needed.
The original TGVs had 25kv cables running along the roofs between the end power cars to avoid using 2 pans. This caused some consternation with the UK safety industry at the time but has since become the norm.
K
edwin_m
Veteran Member
TGVs did and do run in multiple, so there would be two pans raised in the formation, but nearly 400m apart. I don't know if the OLE on the LGV high speed lines would have been compatible with a single unit with a pan raised each end (and no 25kV connecting cable) putting the two pans rather less than 200m apart - similar to two five-car units on GWR but at higher speed.
The 'bible' for OHLE info is 'Overhead Line Electrification for Railways' by Garry Keenor - it's a 376 page book last revised in 2021 and it can be downloaded for free at the following link in PDF format (180MB in size):
https://ocs4rail.com/downloads/
Although the download is free the author would appreciate donations to the Railway Children charity (donation link on the download page). Of particular interest is Chapter 14 (starting on p.189) which explains the basic differences between UK OHLE types (including some rarities such as the Brown Boveri system used on the Neilston branch in Scotland). Greater technical detail of differences is given in Appendix D starting on p.339.
https://ocs4rail.com/downloads/
Although the download is free the author would appreciate donations to the Railway Children charity (donation link on the download page). Of particular interest is Chapter 14 (starting on p.189) which explains the basic differences between UK OHLE types (including some rarities such as the Brown Boveri system used on the Neilston branch in Scotland). Greater technical detail of differences is given in Appendix D starting on p.339.
RyanOPlasty
Member
How much of the structure has to be replaced? IIRC sections of the former Manchester Sheffield 1500v electrification have original steelwork now wired at 25Kv.
And 1920s /30s masts are still going (maybe not strong) in other countries - albeit not on 100mph+ mainlines.
1930s PRR masts are still in use between New York City and Washington DC where Acela trains can reach 150 mph although the catenary itself has been replaced and upgraded in those sections with the highest maximum speeds.
These are enormous masts for height, as they carry not only the traction wiring but, up high, the 33kV (I think) feeders from the power station. which as the original system was at 25 Hz the railway needed their own power distribution system. At points where the railway passes under a road bridge the power feeders are often put way up high, over the road.
This applies to the Picc to Glossop/Hadfield lines, converted to 25kV in the 1980s. Also there are surviving OLE supports between Manchester and Altrincham that have survived conversion from 1500V DC to 25kV AC and then to 750V DC. But I think the recent Guide Bridge to Stalybridge electrification avoided re-using any of the now 70-year-old masts.
GRALISTAIR
Established Member
I am pretty sure that is an absolute definite.
Don Coffey has posted on his channel of cab ride videos a route learning trip from Piccadilly to Hadfield and Glossop taken last year which allows good views of the old OHLE along the route:
At the 9:10 mark where the Stalybridge line diverges all the masts along it appear to be brand new. Incidentally I've seen a photo taken early in WW2 of a steam hauled freight somewhere in the Hattersley/Broadbottom area passing underneath unwired masts so some of them in this area must date from around 1939 when work was started but soon paused.
Another place with old steelwork is from Fenchurch Street to Gas Factory Jct and then to Bow Jct. Modifications to the OHLE took place in the 1980s when Fenchurch St was rebuilt and the DLR was opened but certainly through Limehouse everything seems to be original 1949 steelwork with compound catenary.
At the 9:10 mark where the Stalybridge line diverges all the masts along it appear to be brand new. Incidentally I've seen a photo taken early in WW2 of a steam hauled freight somewhere in the Hattersley/Broadbottom area passing underneath unwired masts so some of them in this area must date from around 1939 when work was started but soon paused.
Another place with old steelwork is from Fenchurch Street to Gas Factory Jct and then to Bow Jct. Modifications to the OHLE took place in the 1980s when Fenchurch St was rebuilt and the DLR was opened but certainly through Limehouse everything seems to be original 1949 steelwork with compound catenary.
Chris Hamilton
Member
I’m not entirely sure what you mean by “Mk1 Signalling Systems” as we use no such designation. We do often refer to individual items of equipment by that designation, such as “Mk3 Clamplock Points” (which have a redesigned detection and locking mechanism) or “Mk3 Solid State Interlocking” (just a refinement - still dating back to the early 90s - of the 80s BR SSI design), but no collective signalling system is referred to as Mk anything.
The signalling across the WCML is a hodgepodge of late 60s Route Relay Interlocking, 70s Geographical Interlocking, 90s Solid State Interlocking and most the most recent Westrace installations at Carstairs, and trains regularly run at 125mph on all of those types.
My section, for example, has patches - long and short - of 125mph running for about 50 miles south of Carstairs. The entirety of which (with the exception of a couple of miles south of Carstairs which use a hybrid SSI system dating from the early 00s) uses a GEC Geographical Interlocking system, designed in the late 60s and installed around 1972, with a reasonable amount of the equipment still in use dating from that time. There has been a couple of modern things bolted on, such as new transmission systems (that allow distant interlockings to communicate with the signabox) due to the older GEC equipment being very much obsolete and it being recontrolled from Motherwell to WSSC, and the majority of signals have had their filament lamps replaced with LED lamps (like you would do in your house), but if my colleagues from a 1970s Carstairs S&T popped back into existence, they would very much recognise the signalling equipment, on a line with regular 125mph tilting trains, and that is the situation for a heck of a lot of the WCML, even after WCRM.
I understand that some of the masts on the NR section of line from Deansgate to Trafford Park are also from the original 1500V DC electrification of the Manchester South Junction and Altrincham Railway which would date them back to the 1930s..
As far as the former Cornbrook Junction, maybe, but beyond there it was originally wired with low-speed tram-wire type overhead, limited to 30mph or so.
EDIT Sectional Appendix (https://sacuksprodnrdigital0001.blo...tern (North) Sectional Appendix June 2024.pdf) says 40mph.
edwin_m
Veteran Member
Images of the MUFC station show 1980s-style headspans, and the 1500V here didn't connect to Woodhead so couldn't have run any freight, so it's very unlikely that there was 1500V electrification west of any run-off at Cornbrook Junction.
The structures from Cornbrook towards Oxford Road may well be former DC ones, see for example https://maps.app.goo.gl/3ABbNQaayBjYf9MCA
I think at least some of the structures on the viaduct between Oxford Road and Piccadilly could also be former DC ones, there's a good photo in Wikimedia Commons:
https://commons.wikimedia.org/wiki/...va_Rail_North_156455+156452_Preston_train.JPG
The Mk1 type catenary would have been installed when this section was converted to 25kV AC in 1960 but to me the portals look older.
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