Friday, 4 July 2014

From Ditton to Lime Street

The plan

In my submission for an HS2 spur for Liverpool and what could also act as the part of the Liverpool to Manchester start of HS3, I have always intended that one option was to convert the line to GC standard and allow full High Speed trains to run through to a new station under Lime Street via the Victoria Tunnel. The cheaper option is to use classic compatibles on the route and terminate in the existing Lime Street, while this would both bring the journey time down by a considerable about, as the trains could run unimpeded and at high speed for longer and free up capacity on the WCML for freight for the Port of Liverpool. It does not take advantage of the longer trains for that additional work is needed and new longer platform.
HS3 Junction
The point at which the line east of Warrington crosses the proposed HS2 route is approximately 1 mile north of the junction from HS2 to the Manchester spur. It would be possible to provide an additional link between the Liverpool and Manchester Spurs rather than taking up space on HS2.

HS2 to Ditton

The run from HS2 to Ditton is not electrified and if it was expanded to GC Gauge and electrified this would have no effect on the existing use of the line. However, there are several bridges, the height under which may need to be increased to allow for electrification and GC gauge. This can be done in two way raising the bridge or lowering the track or by a combination of both. As the track can be worked from either end this should not present a major disruption to services.
It would be useful if the tracks could still be used by standard WCML trains to accomplish this the OHLE would have to be at a height that could be used by both.
The minimum separation between OHLE and the body of the vehicle is 0.15m, if we add this to the 4.65m height of a GC Gauge vehicle we get a minimum height of 4.8m. Current electrical regulations require that at a level crossing there is a 5.6 m clearance, as there are level crossing on WCML this means that there is at least an 80cm overlap between acceptable OHLE heights for GC and WCML. So a section of track within that window would be usable by both.
The minimum clearance from OHLE to static infrastructure is 20cm giving a minimum bridge height of 5m above the rail top.

Ditton to Victoria Tunnel

However, beyond that we are on the 4 line approach to Lime Street. In order to fit GC Gauge trains on these lines. We would need to increase the available height and would have to use the same methods, as outlined earlier, though this would be complicated by the need to continue using the tracks, however, clearance has been increased on other lines without shutting the track there is no reason to believe it cannot be done here.
The additional requirement to allow GC passage would be alterations to the platforms to allow GC trains to pass, this need only be done to platforms on the express lines, any non GC gauge train that needed to use these platforms would need to have some mechanism for bridging the gap, the mechanism to do this are an essential part of the Classic Compatible train design.

Victoria Tunnel

Victoria tunnel
The Victoria tunnel would be used to provide access to a new station under the current Lime Street, however, at 7.9 m wide and 5.5 m in height, the tunnel is not large enough to take 2 GC gauge lines. It is not known whether that height includes or excludes the current ballast depth.
The simplest way to do this would be to lower the floor, while considerable engineering work needs to be done, this is considerably easier and faster to do than digging a new tunnel.
Calculations show that the top of rail height needs to be at least 1.62m below the current tunnel floor. With the use of Ballast free track another 50cm, maybe need so making the total of increased depth 2.12m. At HS2 maximum incline of 1:40 this would mean an include of great the 84.8 meters in length, to drop from current line height to tunnel height.
Floor lowering is by no means uncommon and such work has been suggested for the Victoria Tunnel, in Queensland, Australia.

More information on the HS2 to Warrington section here at East of Lymm 

References





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