Northern Line Postscript: Deep In The Heart Of Camden

Our recent article on future Northern Line upgrades was not really meant to be about one particular aspect but how the pieces as a whole fitted together. It was acknowledged in the title that the biggest contentious issue would be the upgrading of Camden Town station.

The first of these upgrades mentioned – the signalling – is in progress now but attracted very little comment. Whether this is because it is happening in the background or it is because that automatic train operation on the London Underground is now regarded as decidedly passé is hard to tell.

Other aspects of the recent article such as the proposed Battersea extension and Bank Station Capacity Enhancement have been covered before by us in recent years. So it was perhaps, with hindsight, inevitable that a proposed enhancement to Camden Town station to facilitate interchange would attract the most comment. It was also probably inevitable that the whole issue of Camden Town station being completely unsatisfactory for the numbers of people wishing to enter and exit the station would invite a lot of comment, despite clearly not being something that can be done in the timescale for completion of the other aspects of Northern Line enhancement.

The need for interchange facilities and HS2

The provision of good interchange facilities at Camden Town is regarded as essential before the Northern Line could be split – if a split is to be the intention. Some of the comments made the entirely valid point that if inadequate interchange facilities cause passengers to change somewhere else then that, in the bigger picture, would be seen to cause greater problems. A prominent example was Euston. Given that HS2 Ltd probably want the interchange at Euston between HS2 and the Underground to be as smooth as possible, it follows that they will also want to see any split of the Northern Line conditional on the quality of interchange at Camden Town being, at the very least, equal in terms of passenger convenience to that at Euston.

Some of the interchange passages needed at Camden will be quite long. It may be the case, therefore, that an argument could be made to install a moving walkway similar to the one deep below ground at Waterloo tube station to facilitate interchange to the Jubilee line.

Deep Level Shelters

Less expected was discussion of the relevance of the World War II deep level shelters. Taking into account any existing infrastructure when expanding a tube station is always a good thing to do, even if only to ensure one does not get caught out by it during construction – as actually happened at Oxford Circus in the 1960s during the rebuild of the station. This issue with the shelter tunnels was could these be used to an advantage during a possible future reconstruction?

Most regular readers will be familiar with the World War II shelters which were constructed as long deep level tunnels and built with the intention of subsequently using them after the war was over to bypass stations on the Northern Line and hence provide an express service. The idea was a strange one in general and in the rush of war probably no great thought or discussion was given to thinking how sensible an idea this was. Most bizarre of all the shelters in terms of subsequent use must have been those at Camden. The idea seemed flawed on two accounts. The first flaw was the idea that Camden Town would be a suitable station to have trains miss out on their journeys. The second flaw was that, as we shall see, the tube extends into the area of the complex junctions south of Camden Town. In all probability no consideration would have been given as to how the deep shelter tunnels could possibly be connected to this underground complex of junctions to produce a viable track layout. This is especially true when one takes into account that the future “express” tunnels were intended to be in addition to, and not instead of, the existing ones.

Not so secret shelters

The deep level shelters have been documented in many books through the years, and generally merit a few paragraphs or even a full chapter in all the usual suspects such Rails Through The Clay. The most comprehensive book on this subject though has to be the very recently updated London’s Secret Tubes published by Capital Transport in which the subject covers 34 large pages over three separate chapters.

Online it is comprehensively covered by Subterranea Britannica as you would expect. IanVisits reports on a lesser known use for the shelters, Diamond Geezer inevitably approaches the subject in his own way and indeed we ourselves couldn’t resist getting in on the act.

Precise Location

The above picture shows the location of the deep level shelter tunnels, which are shown in black. It can be seen that they are below the existing platforms (in grey) which it must be remembered are themselves on two levels – one for northbound and one for southbound services. Original access to the deep level shelter is shown in blue.

In the images that follow, north rather confusingly is not up the page but to the right.

In the two original plans above we see more precisely the exact locations of the tunnels and crucially, but not particularly relevant to current issues, the fact that they extend under the junction complex. As is often the case there are difficulties locating the position in relation to streets because the street names have changed. Wellington Street had been renamed Inverness Street by 1938. We cannot know if this means that the map are pre-1938 or, more likely, the draughtsman was using an out-of-date surface map as a reference. Park Street is almost certainly today’s Parkway.

Looks good in 2D

Ideas for transport links that initially look like a good idea often fall at the first hurdle. Above ground a visit to the site, or even just a thorough look with Google Streetview, may highlight flaws. Below ground, without an isometric 3D dynamic CAD drawing, it is more difficult to decide whether to progress or to abandon ideas at an early stage.

Despite their name the deep level shelters at this location are not that deep. The crown of the tunnel is only about 18 metres below road level. This was probably determined by the minimum depth that they could be which was consistent with safe construction below the Northern Line tunnels.

The southbound Northern Line tunnels are the deeper of the two and it is estimated that the centre of the tunnel is approximately six metres higher than the centre line of the shelter tunnels. This is about the size of a two storey house up to the roof level and it is difficult to see how such tunnels can be incorporated into any future layout of the station.

Are the Deep Shelter tunnels relevant?

It would appear at first sight that the deep level shelter tunnels are of no relevance – excepting, of course, that you always need to know what tunnels are in the area. This will be the case whether considering their use for a minimal improved interchange upgrade or a subsequent full-blown station upgrade.

The idea that the deep level shelter tunnels can serve no useful function in this instance, however, may not be entirely true. Much has been made of the difficulty of finding a construction worksite in such a sensitive area. London Underground have not been prepared to give away many details at this stage but verbally they have said that they believe that they would avoid the contention present in the earlier plans over having a building site in the centre of Camden by locating it some distance from the heart of the station.

London Underground’s pronouncement may just mean construction of an temporary angled shaft for access purposes, or alternatively it may mean using at least one shelter tunnel to access the station work site. This would not be an entirely new idea. As our piece on the upcoming repairs to the Jubilee highlighted, a similar approach was taken at Old Street during repairs to the Northern Line, with disused siding tunnels used for work site access. If this approach were used again, one suspects this would be from the north where there appear to be various insubstantial commercial buildings of little merit. If at least one of these tunnels were used for this purpose then arguably it would be the first time that any of these tunnels would have contributed to faster journey times as was supposedly their ultimate purpose.

Many thanks to Jonathan Roberts for making the material available to make this post possible.