Introduction
Aims & Objectives
In any mention of the electrification of the lines into East London, it is often stated that the first section of GEML was at 1.5kv DC and then this was replaced by a ‘mixed system’ of 25kv and 6.25kv AC where clearances were considered not permitting. Little elaboration is given beyond this. So I intend here to ascertain exactly which lines in the Anglia region were at 6.25kv and at what times they were upgraded to 25kv. I also intend to piece together an impression of the traction power feeding arrangements at various points in time. For both these, I will construct explanatory maps and diagrams to display this information visually, perhaps for the first time.
This is also part of a wider study in establishing basic information about electrical control rooms on the British rail network both past and present; so some mention is given to that topic where revelations are made. I declare my intents here so as to remind any concerned that many of the sources I have consulted also give good detail on many other aspects of past electrification projects (financing, civils, remodelling, signalling, OLE systems, rolling stock, timetabling, etc) however I have not generally made note of these other topics.
Context & Overview
In 1949 the GEML between Liverpool Street and Shenfield was electrified at 1.5kv DC. This was followed in 1956 by an extension of the system to Chelmsford and Southend Victoria. In 1959 Colchester to Clacton was electrified at 25kv AC as one of two early pilot schemes into high voltage AC systems using industrial frequencies. In 1960, Liverpool Street to Southend was converted to 6.25kv AC (a compromise voltage to accommodate the tighter clearances that 1.5kv DC could achieve) with Shenfield to Chelmsford converted straight to 25kv two years later.
Also in 1960 the lines from Liverpool Street to Hertford East and Bishops Stortford via the Southbury Loop, and to Enfield, and to Cheshunt were electrified with the mixed system of both voltages (known as the 'Chenford' scheme). Then in 1961 all lines out of Fenchurch Street were electrified with the mixed system as well; this was the introduction of new 6.25kv electrification. Seemingly all EMUs built in the 1950s, 60s and 70s for this region were capable of dual voltage operation until the introduction of class 315s in the early 1980s.
In 1969 the Lea Valley mainline route was added at 25kv AC and from 1975 it is said that conversion to 25kv started to take place on all lines. From 1985 new schemes brought further extensions to the 25kv in the region. By 1987 electrification had reached the end of the GEML at Norwich (along with the branches to Braintree, Southminster and Harwich) and as far as Cambridge on the WAML with the last stretch to Kings Lynn opening in 1992. By the time of the introduction of class 357s on the LTS network in 2000, it would not have been possible for any 6.25kv lines to still exist.
From the late 2000s work began to re-equip the OLE system between Liverpool Street, Chelmsford and Southend because the 1940s/50s designed registration, support and tensioning systems had become unacceptably unreliable. In conjunction with this, autotransformer feeding was installed in the Shenfield in connection with the Crossrail project.
Sources
Present day Network
For AC overhead systems, voltages and feeds have to be separated by neutral sections. Because neutral sections are important to train drivers and their regular duties, they tend to be the best attested components of feeding arrangements. Neutral sections are listed in modern sectional appendices and on the archive website railwaycodes.org.uk which together give a generally accurate account of neutral section locations for present day installations.
The website openinframap.com claims to have recorded all grid transmission and top level distribution lines currently active, and since GB 25kv AC systems connect to the grid at ≥132kv substations, a combination of OpenInfraMap and the sectional appendices that Network Rail have started publishing online can give an indication of feeder station and MPTSC/MPATS sites on the present day network, in lieu of better information. Recent cab ride videos and satellite imagery can somewhat allude to track sectioning locations. Furthermore, work related to new installations are sometimes mentioned in corporate media bulletins (though occasionally with un-corroborative factuality).
One of the most instrumental sources I have continually reffered to in this project is a set of blurry images taken of Romford ECR's mimick panel in August 2010. Although a lot of detail is missing and a lot of subtleties are likely lost on me, they still give a good general sense of the feeding arrangements immediately prior to alterations made for the autotransformer system. The pictures are publically available of the always insightful photos.signalling.org. In addition to this, there is one very blurry picture of Romford ECR's new TPCMS (Traction Power Centralised Management System) VDU board taken (presumably during testing) in November 2017. This I found from an unlikely source called Highways Today, one of a fair number little known corperate periodicals that has reported on Network Rail's modernisation of electrical control (princapally the renewal and standardisation of SCADA technologies into a new system known as TPCMS). It is the banner image of an article they published on the 12th of March 2018 when the new system was commisioned at Romford titled "Traction Power Centralised Management System goes live for Network Rail upgrade" that can be read here. I take some measures to communicate in this text what these sources actually are rather than just "click this link" as I know all too well how links can very easily go missing over time.
Historical Network: Primary Sources
For historical feeding arrangements, British Railways Working Instructions booklets for various installations are usually well detailed for this topic. I was able to access a 1956 booklet for the Liverpool Street/Fenchurch Street to Chelmsford and Southend Victoria DC system (includes information on the original Liverpool Street to Shenfield extent as well), a 1958 instructional on the Colchester to Clacton pilot scheme, for 1960 LTS AC system and for the 1960 Great Eastern and Lea Valley lines (Liverpool street to Chingford/Enfield Town/Hertford East via Southbury).
These working instructions include information on the relevant electrical control room, location of substations and track sectioning sites, and a detailed line diagram with signal boxes, wiring extents and neutral sections shown although it is vague on exact mileages. However, it appears that this kind of internal publication about a specific installation stopped being produced at some point and British Railways instead issued general instruction booklets harbouring much of the same information as the earlier ones in regards to staff procedure; but without any specific information on the locations of ECRs, feeder stations or TSCs that were in operation at that time. The only useful information to be gained here is the list of neutral sections with mileages in appendix B. One such publication of this type was available to me dating from May 1975.
Interestingly, the high profile failures of certain EMUs introduced to the North East London area in connection with the Chenford scheme caused several highly detailed Ministry of Transport reports to be written and are publicly available on the RailwaysArchive website. The final report includes high quality information on voltage boundaries, feeder stations, TSCs and electrical control arrangements for the LTS, GE AC conversion and Chenford systems as they stood at 1962. Perhaps relevant to a different project, it also include similar information for the Glasgow North of Clyde area, Lancaster/Morecambe/Heysham 50hz install, the first stage of WCML electrification from Manchester to Crew including the Styal line, and - of course - highly specific information on EMU components, circuitry and functionality. This has given some extra insight for Chenford and GEML feeding arrangements at the original AC installation in the early 1960s. From the MoT reports, the 1960/1961/1975 Working Instructions, we can locate the neutral sections of the GEML, LTS and WAML networks to the mile and chain. There are not any discrepancies between the neutral sections listed in 1962 and 1975 (with one exception) implying feeding arrangements stayed largely the same in that period.
Mention should also be made to an edition of a short lived magazine called Railway Pictorial and Locomotive Review which was apparently one of three mostly unsuccessful periodicals started by a G.H. Lake in the 1940s and 50s. Each time he endeavoured to specialise in high quality photographs and diagrams to be a focal point of each publication. But most of G.H. Lake’s ventures seemed to be either unsuccessful or moved on without him. But where he was able to publish, the quality of information and detail is unexpectedly high including when dealing with (at that time) contemporary developments. From Railway Pictorial and Locomotive Review, a 4 part series (of February, March, May, June 1950) was dedicated to the new DC installation between Liverpool Street and Shenfield was available to me. It includes many elucidating and likely rare photos of the scheme when it had just opened and during construction. Of particular note is around 1000 words written on the operation and functionality of the Chadwell Heath electrical control room. This is the most I have seen reported anywhere on a specific ECR, either historic or modern.
(More information about G.H. Lakes' magazines can eb found on hte page for the Great Eastern Society's purchasble scans of his publications. From the index that I can view, he could have good insights into early Merseyside electrification schemes.)
Historical Network: Secondary Sources
The main work that touches on this subject is John Glover's Eastern Electric (2003). While the book gives good information on the feeding arrangements of the original DC system and on the AC systems around 1961, less and less detail on that subject is given as the book progresses and very little is given about the timeline of 6.25kv to 25kv conversion. Exceptionally, I was able to access the back catalogue of the Great Eastern Journal (the periodical of the Great Eastern Railway Society) which ran a series of seven articles by John Baker (1992–1994) about the history of Eastern Region electrification. Conspicuously, however, the articles only concern themselves with the period 1949–1969 and so while they added some good details to these systems, on the whole the Great Eastern Journal did little to help with understanding the chronology of 6.25kv electrification.
In short, information on feeding arrangements is not well documented past the early 1960s in the literature I could find. Both Glover and the Great Eastern Journal (itself mentioned as a source to Glover) would surely have used the same “Electrified Lines: Working Instructions” that I could find (Glover explicitly cites a few). I wonder if this kind of technical detail is not sought after for a historical era that could be considered ‘modern’. After all, those early electrification schemes are old enough to intersect with the era of steam traction that has, for many years, driven the scholar-enthusiast interest in railways. Or perhaps that the change in BR policy around electrified line instructional booklets equally affected the secondary sources as well as myself.
Returning to the website RailCodes.org.uk, they also present an extensive timeline of electrification dates on the mainline network, and on the aforementioned page about neutral sections, occasionally mention a historical neutral section or one added as a modification. From this I gather that significant feeding modifications must have occurred to the GEML in the mid to late 1990s. However, RailCodes.org.uk does not mention its sources, and in terms of its electrification scheme dates, there are a few statements it makes which I believe I have the proof to challenge.
Furthermore, Garry Keenor’s (2021) high quality and freely available primer on OLE systems also includes a chronology of when all GB OLE installations were opened. It is in this book that the first mention I found of when 6.25kv systems became 25kv in the 1980s was given. Keenor does not, however, say much about feeding arrangements in practice. I also consulted Keenor’s main source The Age of The Electric Train by J.C. Gillham (1988) which added some extra detail about rolling stock moves but is still suitably vague about the Lea Valley lines. Finally, Ian Cowley’s Anglia East (1987) has been consulted as well. This book does not generally discuss feeding arrangements or voltage changes and is mainly focused on the extension of electrification from Colchester to Norwich and Harwich. Though it does have the occasional relevant insight.
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