Covenants, Easements & Wayleaves: The Hidden Urban Interfaces Which Shape London Part 1

The Underground isn’t just defined by its infrastructure, but by its interfaces too. We look at the hidden world of asset interface management, and how it affects, and is affected by, urban railway management, and uncover more that can be achieved.

On the morning of 8 March 2013, a driver of a northbound main line railway service on the Northern City line between Moorgate and Finsbury Park noted the ingress of water into the tunnel. They communicated this to line control and the driver of the following train was instructed to proceed slowly and observe the situation. When he reached that point of the tunnel, he immediately stopped his train and, after reporting back, line control immediately halted all services between Moorgate and Drayton Park. The driver had spotted two augers that had pierced the tunnel.

This caused the suspension of services on this section of the line for several days.

The subsequent investigation of the event by the UK Railway Accident Investigation Branch (RAIB), identified that:

• the northbound tunnel was located under private land;
• the southbound tunnel was located under the adjacent main road;
• boring was underway to provide piles for a new surface development;
• 19 of the 39 proposed piles would have intersected the northbound Tube tunnel;
• the longest piles would extend over 9 metres below rail level.

The subsequent report stated that the developer of the land above:

The planned augering could well have been much more serious, as the above diagram shows. Had the augers pierced the tunnel at the wrong moment, they could even have drilled into a passing train, causing injury, derailment, and possibly death.

The complex world of interfaces

Despite the complexity of urban underground metro infrastructure and its interconnected relationship with its surrounding environment, there appears to have been little to no standardised scientific approach to analysing the way that railway infrastructure interfaces with its surrounding environment. This is perhaps because it requires a genuine multi-disciplinary approach: including legal, civil engineering, historical, geographical, transport, and urban planning considerations.

It is important to understand what the term interface means in this context. It is not about the boundaries between things, but the ways in which transport and urban infrastructure and its surrounding environment come together and affect each other.

The image below shows the physical interfaces between the railway infrastructure and its environment, of a building over a Metropolitan Line tunnel north of Farringdon. They consist of a retaining wall, supporting adjacent land and road, a tunnel under a building, and just visible in the right hand corner are girders forming part of a fly under for National Rail infrastructure (used by Thameslink):

The following image shows the corresponding property ownerships, colour-coded as follows:

• red (A) London Underground land and airspace;
• green (B) Network Rail land and airspace;
• light blue (C) TfL Streets highway;
• purple (D) local authority highway.

Appreciating the interfaces

“Have you ever considered why this is a one-storey building?”

The question is asked of us by Dr Nathan Darroch, formerly a Land and Vesting Engineer at London Underground, now Research Fellow at the University of Aberdeen, and part time Lecturer within the Schools of Engineering and Civil Engineering and the Built Environment at London South Bank University.

The building in question is a cafe on Palmer Street. It is a one storey building, surrounded by others that are not.

“Until the 1920s,” he continues, “St James’s Park station sat within an open cutting with a roof, similar to other sub-surface stations on the western end of the District and Circle lines.”

“Eventually, however, rising car ownership meant an increasing demand for car parking space in central London, including among directors of London Underground – then the LER [London Electric Railway Company] – working at 55 Broadway, just across the road. Due to limited opportunities for land ownership nearby, LER were forced to think creatively. So they built their car park on the only strip of available land, and airspace, they owned: above the narrow railway cutting.”

It is this, Darroch explains, that accounts for the single storey cafe building today. Whilst the usage may have changed, but the interfaces have not. The building takes its support from the old retaining walls forming the cutting. This is an interface that is over 100 years old, but still in use today.

Indeed, the supporting structure for the building is clearly identifiable from the Victoria end of the westbound platform. As are the different natures of construction for the Palmer Street overbridge constructed with the railway around 1865 to accommodate the existing road (required by law); the office buildings forming part of the 55 Broadway complex; and 55 Broadway, itself (constructed in the late 1920s), and the building above the western St James’s Park station entrance, constructed in the 1980s. All interfaces, completed across many decades.

“London is not the only urban interface to have these interfaces.” Darroch says. “But its history does make the complexity of unpicking them interesting. This city has been excavated, developed, tunnelled, bombed, and redeveloped for centuries. And there are so many other contractual issues that greatly complicate construction, repair, maintenance, and redevelopment besides.”

Land acquisition and management

As Darroch explains, some of this dates right back to the way in which the Underground, as we know it today, was legally created. By 1845, the UK was experiencing a railway mania. The legislation for authorizing railway construction was based on centuries old principles dating back to the Roman era, including responsibilities for bridges and land acquisition, which had later been adapted for canal construction.

“The construction of railways saw the adoption of similar principles of land acquisition seen in the construction of roads, bridges, and canals, but these were based on the interpretation of lawyers within the Houses of Parliament, rather than a standardized procedure.” Darroch adds.

“This was remedied with the passing of the Land Clauses Consolidation Act 1845 (LCCA) and the Railway Clauses Consolidation Act 1845. But these still needed refinement. This happened in 1863, when they were both amended. These laws are still in force today.”

The London Underground, however, was different. Its unique sub-surface nature required specific legislation of its own at the time, and this legislation incorporated many of the original principles of the 1845 LCCA.

“Main line railways had to sell their surplus lands within 10 years of their opening,” Darroch offers, by way of an example, “the underground railways could retain ownership of the land for as long as they wished.”

The sub-surface railways, which are generally between 0.2 and 5m below ground level, had basic statutory rights and obligations to acquire land by:

• the right to use the subsoil under a road;
• the ability to compulsorily purchase the whole or part of land and buildings (mostly basements and cellars); and
• the ability to buy an easement under private land and buildings.

This had the effect of half of the Circle line being constructed across, not exclusively under, the street pattern, resulting in the demolition of buildings, construction of road bridges over the railway, and the employment of open cuttings within an already densely developed urban environment.

Some of those cuttings are now covered over to form covered ways with buildings located above, with the introduction of electric trains from 1904. The remaining half of the Circle line is actually under roads, public open space (parks), or within land that forms stations.

Changing the model yet again

By the 1930s, the underground railways were permitted to ‘take’ the subsoil and land they required for the construction and presence of their infrastructure. This enabled the Tube railways to cut across street patterns for more considerable distances without having to buy an easement or land. Compensation was only paid for loss of land or sub-soil where there was an adverse effect on existing or proposed urban development, where this was already proposed at the time of the railways construction. This principle was introduced as the sub-soil was considered worthless to the majority of property owners as they had no use for it

As with the thinking for the early Tube railways being allowed to purchase easements under property, this change had little effect on property development at that time, due to the low height and depth of buildings. The main effect of this new railway was at line interchange station sites, where existing stations were increased in size and capacity below ground, as:

• this could affect the presence of existing buildings, and
• as well as affecting the presence, property, and protection interfaces between the railway and those buildings.

Kingsgate House development, Victoria Street, Westminster

A recent example of effective collaboration between an adjacent land owner/developer and the underground railway owner was the Kingsgate House development on Victoria Street, central London. In this instance, the original building, directly adjacent to the District and Circle lines, was entirely demolished and a new development consisting of eight storeys below ground level, as well as foundations to support 14 storeys above ground level, were erected.

Just how problematic this situation could have been is highlighted by the images below, which show the basement excavation and the property ownerships at the site in question:

where:

• red, labelled A – land, airspace and subsoil owned by London Underground;
• blue, labelled B – land, airspace, and subsoil owned by the developer;
• green, labelled C – land, airspace, and subsoil owned by an interfacing stakeholder to London Underground;
• blue hatched with red, labelled D – land, airspace, and subsoil owned by B; within which London Underground has an easement for the presence of its tunnel;

Without London Underground’s input, the risks to the railway would have been high, both to its infrastructure, and as the auger incident demonstrated, to passenger safety and service levels. However, with London Underground’s input, there was no adverse disruption to the railway, its assets, services, or passengers, and the new development was completed safely.

The arc of a covenant

So far, so complex. But it gets worse. Where the sub-surface railways had purchased land that was surplus to their requirements, they could sell or lease it for urban development. Within the sale or lease, they also had the opportunity to impose protection for their infrastructure in the form of covenants. This is a contractual requirement, mostly to consult and gain the explicit consent of the transport infrastructure owner, before carrying out any work on the land (eg demolition, building extensions at roof, ground, or below ground, etc).

New techniques bring new laws

If every piece of the covered Underground involved an active covenant, then managing its interfaces would be considerably easier. However, land was not always purchased, meaning that covenants could not always be imposed.

This became even more common as tunnelling and electrification technologies advanced. This meant deeper railways which were anticipated to have a considerably lesser effect on their surrounding environment. As a result, changes to land acquisition were incorporated within the authorizing legislation for Tube railways.

“This included the ability to only buy an easement under private property, or to use the subsoil under public highways free of subsoil purchase costs.” Darroch explains, “Indeed the latter became the option of choice for much of the expansion between 1890 and 1907, to save having to pay sometimes extortionate prices.”

“For example, to go under the warehouses near London Bridge, the builders of what is now the Northern line had to pay £3,000 for an easement of fifty to sixty yards. That’s about 2% of the property’s rateable value of about £150,000.”

“Mitigating the need for incursion under private property, often by locating one Tube tunnel above another under the road, became a common feature of future lines.”

Maintaining the tunnels under roads, however, has had an adverse effect on today’s network, where services are limited by the tight curvature of the tunnel alignments. For example, the Bakerloo line between Charing Cross and Oxford Circus stations follows the roads above, including 90 degree turns in the tunnels, which impose very low speed restrictions to this day.

Foundations go deeper

Where the subsoil was acquired through an easement, the railway had no ownership of that subsoil. In effect, what was granted was simply a right to pass through it. Given the depth of much of the Tube network, this was not really seen as an issue in the first half of the twentieth century, but it has serious implications now.”

“Up to the 1950s, most buildings had only one or two basement levels and shallow foundations.” Darroch explains. “Since then, however, buildings have become ever taller, requiring considerably deeper piled foundations.”

“This has led to increased potential presence, property, and protection interfaces between the underground railway infrastructure and its surface environment, through potential conflicts between the use of the subsoil for transport and urban infrastructure.”

Here is one of Darroch’s presentations that shows the complexity and extent with a number of asset infrastructure interface examples.

How can we better know what is underground?

The infrastructure impingement example noted at the start of this piece shows that modern London, indeed every major city, is becoming too complex to rely on individual professionals, or professions, to ensure critical knowledge of infrastructure location and ownership.

As a result, what was really required was the development of a new discipline to deal with the complexity of identifying, classifying, and storing such data, so that a process could be established to make it much easier to check for any issues.

In the next part, we delve into more detail of Tube and Metro tunnel infrastructure interface issues. These principles still apply today for new underground railway infrastructure, such as Crossrail.