Thursday, 22 September 2016

The Green Line

The quest for more green space in Liverpool continues.

The High Line

New York has the High Line Park, a disused overhead railway converted to a park.
The High Line by Beyond my Ken
Unfortunately, the Liverpool Overhead Railway was not only closed but demolished in the 1950s

Even after that had gone, between Sandhills and Exchange, there were a large collection of raised lines of which only a small amount now remain, some of which carry Merseyrail, a small unused section running parallel to Love Lane seem to have greened itself but there is no access. It only 250m long but with something to separate it from the rail would make a park. Some of the bridges over roads have been removed, so it would not be the cheapest park in the world.

The Very Low Line

There are a lot of people asking for more green places in Liverpool, the problem is there are very few places that do not have more profitable uses, but there are a few.
When Lime Street station was first opened  it was connected to Edge Hill via a tunnel. The tunnel was not well ventilated and the build up of smoke caused vision problems, which lead to several accidents, so in 1881 large portions of the tunnel were opened out.
Opening out the tunnel
As time past and signalling improved the ventilation became irrelevant and some places had the cuttings covered over. The most obvious section was the section through the university from Brownlow Hill to Crown Street in 1965, only a small section now remains open.

Courtesy of Graham Newell

Courtesy of Graham Newell
 The changes can be seen here on side by side maps.
Lime Street Approach, cuttings outlined in black
The total length of the cuttings combined is about 676 meters, with a width of at least 16 meters, which give a total area of 10,816 m2, 1.08 hectares or 2.6 acres.
Cuttings North of Kirkdale on various lines.
These are deep cuttings, the system used to cover these was large I-Beams at the surface level, so leaving a large amount of space over the lines. The walls of the cutting act as the load bearing element. I'm sure the beams could be placed closer to the track or arches within the cutting but this might be more difficult while the track is in use. Though if you were building a structure above it would provide some basement space.  

In addition to the cuttings above, there are others in Dingle.

The Not so Low Line

There is another technique that has been used down south most notably at Gerrards Cross, though it made the news for all the wrong reasons, see the Gerrards Cross Tunnel Collapse. This is suitable for shallower or wider cuttings, it could even be used on surface lines to reattach 2 pieces of land, bisected by the railway leaving with only a modest hill.

Timo Newton-Syms
Timo Newton-Syms
As you can see it was quite a simple idea put an arch over the line then back fill. Like a rather delayed Cut and Cover operation. This was all done while the line remained in operation. The technique is sufficiently common that specialised systems exist and several projects have been completed since Gerrard's Cross, such as  BEBO® Concrete Arch System & Tech Span  PreCast Arch
There are several places that such a system could be used on Liverpool's various used and disused railway, perhaps the most obvious are near Kirkdale and perhaps the main line at Speke.

Things built over railway lines

Mutley Plain Car Park, Plymouth

Spring Road Station
The bridge beyond station is a multi-storey car-park built for the former Lucas factory site off to the right.

Update March 3rd 2017

On 1st March part of the retaining wall on, one of the cuttings collapsed, scattering 200 tonnes of wall and earth over the track, bringing down the overhead lines and unsurprisingly bringing trains to a halt, the current estimate is it will take a week to get it sorted. The deep set arches at the level of the old tunnel roof seem like a good idea now, put them in and cover to a depth of a meter in concrete, to protect the track.  The in the space above cellars car park whatever and a garden on the top, or more car park.

See Owner of land next to collapsed Lime St wall previously sanctioned for "double stacking" containers

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