East Coast Mainline Routes & Branches Part 2: The Hertford Loop and the Northern City Line


This article grew in the telling. As with so many other places on the London rail network, it is hard to give a comprehensive overview of plans for one improvement on the East Coast Mainline (ECML) without attempting to coherently explain neighbouring developments that influence or shape those plans. This is one reason why the Thameslink Programme features so often on London Reconnections; it has a huge impact on existing services both north and south of the river. The London end of the ECML has several branches, whose routes are currently integrally intertwined and overlapping. Here, Thameslink will absorb some services and create significant opportunities to rethink others.

While this article was initially intended to focus on the segregation of the Hertford Loop from other suburban services, no real justice can be done to this topic without also setting it in the context of its eccentric spouse, the Northern City Line. Nor can the future of the Hertford North – Moorgate service that they carry be fully understood without examining the huge impact that segregation and Thameslink will have on that service’s twin, the Welwyn – Moorgate route. All of this has become especially topical following the belated release of the combined Thameslink, Southern and Great Northern (hereafter, ‘Greater Thameslink’) Franchise consultation response and Invitation to Tender. These documents finally answer (at least in outline) some of the outstanding questions concerning the future of services on the ECML and the Northern City Line.

So in this, the latest in our occasional series on the ECML and its London branches, we will look at the under-publicised work to increase suburban service levels on the ECML Great Northern routes, and the impact of the new franchise specification.

A Potted History

As we detailed in our earlier look at the Past and Future of Finsbury Park, the Hertford Loop and the Northern City Line had separate origins prior to being connected in 1976. The loop began in 1871 as a branch line connecting Alexandra Palace station (1859, then called ‘Wood Green’) on the ECML to Enfield, and did not reach Hertford North until 1924. The original Enfield station and spur were demolished in 1974, three years before the branch was electrified. The Great Northern & City Railway, on the other hand, was opened in 1904 to connect Moorgate and Finsbury Park by tunnel, and was not linked to the ECML until the post-Victoria Line changes of the late 1970s. Subsequently, the Hertford Loop has comprised a substantial part of the inner-suburban ECML services running into Moorgate (during weekdays before 22:00) and King’s Cross (during late evenings and weekends).

The Hertford Loop consists of three stations outside the TfL area (including Hertford North), and a further seven within it. The loop then joins the ECML at Alexandra Palace, from where the route serves Hornsey (1850) and Harringay (1885) stations, before leaving the ECML at Finsbury Park to join the Northern City Line. The route then serves five stations, culminating at the Moorgate terminus, including a notable cross-platform interchange with the Victoria Line at Highbury & Islington.

Southbound inner-suburban services on the ECML from Welwyn Garden City merge with the Hertford Loop services at Alexandra Palace (after serving five stations outside the TfL area and only four within it). This, and the mixture of stopping and semi-stopping services, causes capacity constraints on the shared track between Alexandra Palace and Finsbury Park, and has long prevented any significant increase in service levels.

North Thameslink

Diagram of Inner Services to King’s Cross and Moorgate taken from the DfT’s Greater Thameslink consultation response document.

The current service level is as follows:

Off peak:

  • 3tph Moorgate – Hertford North (with 1tph extended to Stevenage)
  • 3tph Moorgate – Welwyn Garden City


  • 4 – 5tph Moorgate-Hertford North
  • 3-4tph Moorgate – Gordon Hill
  • 3-4tph Moorgate – Welwyn

(So timetabled that Moorgate currently receives no more than 12tph)

Some peak trains on the Loop start or terminate at Gordon Hill, others continue to Stevenage or Letchworth. The Welwyn-Moorgate service is supplemented at peak times by 1-3tph semi-stopping from King’s Cross to Welwyn, Stevenage, Hitchin or Letchworth.

Increasing Capacity on the Hertford Loop

The need to increase capacity on the Hertford Loop has been recognised for some time. The 2008 ECML Rail Utilisation Strategy (RUS) recommended that all three-car peak services be increased to six-car, which is the maximum length that the Northern City Line stations can cater for. It also called for the off-peak service be increased to four trains per hour, and for the peak-hour service to be raised from 12 to 15tph, the ‘absolute limit’ of the Northern City Line track and platform capacity (actually the practical maximum under modern standards – the NCL originally handled 18tph); these would be additional Hertford-Moorgate trains.

However, the ‘second generation’ 2011 London & South East RUS (which brought together and updated the various ‘first generation’ RUSs that cover London) suggests that the planned additional capacity on the Hertford Loop will be accommodated by the withdrawal of the Welwyn-Moorgate service, rather than through increasing the number of trains terminating at Moorgate from 12 to 15, stating:

Following completion of the Thameslink Programme it is assumed that the current peak service into Moorgate will remain at 12 trains per hour as today. However, several of the existing Welwyn Garden City to Moorgate/London King’s Cross services are anticipated as being re-routed through the Thameslink route tunnels … Capacity would be freed up on the Moorgate branch if this element was implemented, enabling a frequency increase to 10 trains per hour on the Hertford Loop.

Despite this, a residual Welwyn – Moorgate service is expected to remain post-2018. While minimum standards have been set in the Greater Thameslink specification, specific details of these services will be determined by the future franchise operator.

The capacity limitations that we have seen above, and the diversion of some Welwyn – Moorgate services and passengers to Thameslink, mean that passenger numbers into Moorgate are only expected to grow 1% by 2031, whereas Great Northern/Thameslink traffic into King’s Cross and St Pancras will grow by 66%. This seems to assume that increased capacity on the Hertford Loop will ease overcrowding without stimulating significant growth in the number of passengers wishing to alight at the Moorgate terminus.

The 2011 RUS states that:

Beyond 2018, the Thameslink Programme will alleviate suburban capacity constraints and improve connectivity, by enabling commuter services to continue through the Thameslink tunnels, rather than needing to terminate at London King’s Cross. However, no (or very few) additional peak trains relative to today will be able to run through the critical Welwyn viaduct area, so it is likely that frequency increases in the morning peak will generally be restricted to inner suburban services. These will benefit from a combination of the Thameslink Programme and committed infrastructure enhancements in the Finsbury Park to Alexandra Palace area, with six fully usable tracks planned.

It is those infrastructure enhancements that we will examine next.

Segregating the Hertford Loop

As we noted in the introduction, no increase in trains per hour can occur on the Hertford Loop without at least partially untangling Welwyn and Hertford stopping services between Alexandra Palace and Finsbury Park. For some time work has been under way to convert a goods track south of Alexandra Palace into a second up slow track (i.e. from the country to Moorgate) for passenger use, allowing for segregation of the two services (two lines can already be simultaneously used as down slows). This project will mean that there are six passenger tracks in between Alexandra Palace and Finsbury Park, in addition to a tangled web of tracks linking the Ferme Park goods depot and the Hornsey and Bounds Green train depots.

Harringay and Hornsey looking north, Glover & HayHarringay and Hornsey looking north, Glover & Hay

In addition to resignalling the goods track for passenger use through the addition of AWS (Automatic Warning System) and TPWS (Train Protection & Warning System), this plan requires the re-instatement of the disused up platform at Finsbury Park and associated station accessibility improvements, in addition to extra platforms at Alexandra Palace, Hornsey and Harringay and revised access to the Bounds Green Depot. Work at Alexandra Palace and Finsbury Park is now nearing completion, and we understand that the Bounds Green depot access works have been completed as part of the Thameslink Hornsey Depot works.

The Impact of Segregation on Harringay and Hornsey Stations

The precise plans for Harringay and Hornsey Stations remain somewhat opaque. It would appear that since the 2008 RUS was published the planned work on new platforms at Harringay and Hornsey have been postponed, perhaps indefinitely. Any mention of these two stations appears to have slipped from the Control Period 4 (2008-2013) plan, and while proposals for CP5 (2014-19) assume that all works between Alexandra Palace and Finsbury Park will ‘be completed’ by 2018 they do not specify whether this includes the intermediate stations. This led to speculation that service levels at Harringay and Hornsey were under threat, as full segregation of Hertford Loop and Welwyn services north of Finsbury Park would prevent Hertford Loop trains from stopping at those stations.

After local pressure, the DfT suggested that both stations could be served by the 4tph 8-car Thameslink service (in addition to a residual Welwyn Great Northern service), which would compensate for the loss of Loop trains. However, it has not been confirmed whether the platforms will be extended to cater for these 8-car trains in order to avoid using Selective Door Opening. Such extensions would not be technically problematic at Harringay, and LR understands that the recent trackwork to cater for the new Hornsey Thameslink depot now means that extension is feasible at Hornsey too.

However, the author is assured that all trains serving Harringay & Hornsey are likely to continue to be from the Hertford Loop and the residual Welwyn – Moorgate service, with no Thameslink trains stopping there despite their sharing the same track, yet retaining the current 6tph service level. The new ‘Greater Thameslink’ franchise specification appears to leave room for this option. This would mean that Hertford and Welwyn services would continue to use the existing platforms at Harringay and Hornsey. It seems, then, that the current works may result in only a partial segregation of inner-suburban services north of Finsbury Park. Whatever solution is ultimately revealed, it will be interesting to see how the Thameslink and non-Thameslink suburbans are threaded across the new six-tracked railway.

As a result of local compensatory spending attached to the Thameslink Hornsey Depot works, Hornsey station is currently being upgraded using a £500,000 investment by the London Borough of Haringey, Network Rail and First Capital Connect. However, no similar package has been announced for Harringay station. The DfT have announced, though, that both stations will become permanently staffed during opening hours; this is in line with the franchise specification, which calls for all stations with more than one million passengers per year to be permanently staffed. In last few years both stations have crept past the one million mark.

Segregation, Thameslink, and the future of inner-suburban services

As we have explored elsewhere at London Reconnections, a combined Thameslink, Southern & Great Northern service will be created from 2015. This would be the largest franchise in the country. Abellio, FirstGroup, Govia, MTR and Stagecoach all made the original March 2012 short-list, but progress was postponed in October 2012 following the West Coast franchise disaster. The process was relaunched in January 2013, and it has been announced that the First Capital Connect franchise will be extended by 28 weeks from the formal 13 September 2013 end date to allow the process to be completed. The formal Invitation to Tender was released on 26 September.

The 2012 Thameslink franchise consultation suggested that non-Thameslink great Northern inner-suburbans could be detached from this mega-franchise, and passed to an Inter-City East Coast franchise. The newly-published Consultation Response and Invitation to Tender note that this was not a popular option, and confirm that the residual inner-suburbans will remain with the Greater Thameslink franchise.

Yet the consensus seems to be that the train operating companies tend to neglect inner-London stations and services in favour of more lucrative long-distance customers, and therefore there are legitimate doubts as to whether either franchise option best serves commuters in London and Hertfordshire. In light of this, questions are being asked as to whether TfL control of these services might now be in order.

Back in May, our own Walthamstow Writer noted an interesting exchange between London Assembly Member Joanne McCartney and Sir Peter Hendy:

Joanne McCartney asked if the Great Northern stopping services into Moorgate were being looked at by TfL for devolution. She felt it would make sense for these services to be devolved. Sir Peter said this line was a rare example of a London railway where patronage had fallen since the through service had been put in place in the late 1970s. He agreed that the relatively self-contained nature of the service, and it being largely within Greater London, leant itself to being run by TfL. Joanne McCartney added a plaintive “please” by way of closing reply.

It seems this will not now occur before the new franchise ends in 2021. It may be that the chances of devolution occurring after then have been bolstered by (and are contingent upon the success of) TfL’s recent takeover of West Anglia inner-suburban services. That said, the imposed limit of Chingford/Cheshunt/Enfield for this TfL service – rather than allow it to serve destinations outside the TfL area through to Hertford East – may be problematic. If TfL were to be given control of suburban services on the Loop they might well be limited to the turnback at Gordon Hill, where many peak-time services currently start and terminate. In this scenario only a minority of services on the Loop could be TfL-run in order to maintain services to Hertford and beyond, undermining the case for and feasibility of devolution.

Evening & weekend service

The Hertford Loop and the Welwyn route currently endure a 3tph daytime and 2tph evening & weekend service. South of Finsbury Park these trains are diverted to King’s Cross after 22:00 and at weekends; astonishingly this leaves the Northern City Line with no service after these times. The RUS suggested that there was a poor standalone business case for introducing an evening and weekend service due to additional staffing costs. However the RUS was produced prior to the successful introduction of London Overground and the subsequent explosion in passenger numbers interchanging at Highbury & Islington. Further, the business case will improve once Crossrail begins calling at Moorgate, increasing interchange possibilities there. The RUS did note that it might be necessary to introduce a Saturday service in future if other service levels increase due to capacity constraints at King’s Cross, especially once Network Rail is compelled to restrict access to King’s Cross in order to resignal the station.

Delightfully, the new Greater Thameslink Franchise has revealed that passengers will not need to wait until the arrival of Crossrail in 2018 for the introduction of an evening and weekend service to Moorgate. Instead, this service has been written into the new franchise specification, and will be introduced from December 2015 with a minimum 6tph (4tph at weekends) between no later than 06:00 and no earlier than 23:59 (07:30 and 23:30 on Sundays). London’s Cinderella line will finally get to go to the ball.

Beyond Thameslink & Segregation

We have seen that the combined result of the Thameslink programme and Hertford Loop segregation will be an increase in service levels and destinations for ECML inner-suburban customers. Yet these plans will leave the Hertford Loop and Northern City line significantly under-utilised, with the Loop in particular seemingly destined to continue to suffer from neglected stations and ancient rolling stock. Unless TfL decide to stake a claim on these services, they are likely to remain tied to the growing Thameslink franchise.

A comparison of (admittedly notoriously unreliable) passenger figures for the inner-suburban National Rail stations and the parallel Piccadilly Line is very revealing. The National Rail stations often struggle to reach one million passengers per year, while the Piccadilly Line stations approach ten million users. This, along with the impressive success of the London Overground model – improved stock, improved minimum service levels, and a bold place on the tube map – strongly suggests that demand on the suburban ECML branches is currently repressed. This may throw into question the assumptions made about predicted growth and therefore the cost-effectiveness of proposed enhancements. If this is so, how might further growth be achieved?

It should also be noted that the European Rail Traffic Management System is expected to be rolled out on this part of the ECML by 2018/19. The RUS suggests that this “may offer opportunities for improved exploitation of the infrastructure in place from that time”. This implies that Moorgate may be expected to handle its ‘absolute maximum’ capacity of 15tph. Interestingly, the RUS specifically mentions that any additional trains would need to terminate elsewhere, and raises the curious prospect of diverting some trains through the Canonbury Curve and onto the North or East London Line. It does, though, describe this as a ‘limited’ opportunity, perhaps acknowledging the well-attested difficulties of merging services at this flat junction, and the major challenges involved in providing a segregated junction.

The remaining elephant in the room is the question of replacing the existing rolling stock. The 313s date from the 1970s and are the oldest suburban stock in use in London. Their replacement is complicated by the peculiarities of the Northern City Line, which has third rail electrification and which is unsuited for most mainline stock. As yet there have been no announcements addressing this issue, though the cost of making the 313s compatible with the ERTMS signalling so near to their presumed retirement/displacement may force the question before 2018.

London Reconnections maintains a strict policy of non-speculation when it comes to ‘fantasy lines’, and this article will avoid musing on the possible extension of the Northern City Line beyond Moorgate. It appears not to be part of any medium or long-term plans, or even close to being so. Indeed, it seems likely that the most authoritative and detailed discussions concerning that prospect have repeatedly and extensively occurred at the level of the LR Commentariat, discussions that you are kindly invited not to repeat here.

We have seen that the existing plans for the London-end of the ECML, however, will bring considerable improvements for passengers. Yet some questions concerning how service patterns will change post-2018 remain unanswered. Further, the current plans do not make the most of the existing infrastructure for inner-suburban services, such that track and stations on the Hertford Loop and Northern City Line will remain under-utilised, especially off-peak. Time will tell whether TfL eventually seize the opportunity and seek to address this gap, staking a claim on the non-Thameslink Programme suburban services on the ECML and its branches. It seems that this solution might more practical if the Loop and Northern & City service is entirely segregated from the ECML suburbans to Welwyn Garden City, though this would require additional platforms at Harringay and Hornsey. However, the current geographic limitations on TfL services into Hertfordshire (Watford aside) raises doubts as to the feasibility of this option, as Loop passengers north of Gordon Hill would still need to be catered for by a different franchise, meaning that TfL would not be the sole operator on the route into Moorgate.

In the meantime – with the safe assumption that the ‘Greater Thameslink’ franchise does go ahead in its proposed form – it will be interesting to see precisely how suburban services are configured once Thameslink trains begin running through the Canal Tunnels and elbow their way onto the ECML. We are unlikely to know exactly how this will work for some years yet.

Future articles in this series will take a look at London’s lost ECML branches, namely the ‘Northern Heights’ and the Palace Gates Line, focussing on the mooted resurrection of the latter as a branch of Crossrail 2.

Written by Arkady