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Gauging
Gauging plays a key role in the design offices, this being the process of deciding whether
a train can fit on the infrastructure or not.
One job that Corus have been carrying out is gauge analysis of the Leeds to Doncaster line.
GNER have asked to be able to run the Eurostar on this line, and as a consequence, the line
has to be both analysed and modified.
The process for analysing a route can be quite complicated. There is a piece of software
called Clear Route that has the capabilities of analysing a route. The type of locomotive
has to be identified. The profile of the route, gathered by surveying, is put into the
software as well.
Kinematic Profile
The cross section of the train whilst moving. Taking into account parameters such as suspension, velocity, wheel wear, loading etc.
Static and kinematic profiles of all kinds of trains are available, within a database. The
computer can then calculate distances between the train and the surrounding infrastructure,
and overlaps the profile of the train with the profile of the geography. Of course this is
done for one point of the route, and a snapshot is taken at intervals, for example, every 10 m.
Fig XXX shows a cross section of a class 373/2 (Eurostar) at one end of Ardsley tunnel.
This tunnel has required lots of redesign work since GNER have requested to run class 373
locomotives. This includes changing the levels of the tracks, changing the cant, and slewing
the track. To slew a set of rails means to simply move it across, either away or towards the
adjacent line.
This brings into question Railtracks business plan. How have Railtrack justified the expense
of remodelling the Leeds to Doncaster route just to allow an additional two trains per day?
The entire ECML was redesigned and changed to allow for clearance of Class 373/2's, but these
trains only run as far as York. Why don't GNER ask for them to be run all the way to
Edinburgh? I feel that this shows an example of how Railtrack and the SRA need to work more
closely together to ensure that the railways are being developed in the right direction.
For the West Coast mainline (WCML) Virgin have asked to be allowed to run new tilting
trains. Again, this has resulted in a remodelling of the ECML to accommodate the new
locomotives. These have been modelled on Clearroute for gauging purposes. The types of
external factors for the kinematic envelope are slightly different for the tilting trains.
That is, the cross section of the train has to be considered for three different conditions:
upright, tilted and tilt failure. Tilt failure accounts for the train not self-righting after
passing through a curve
Finally, this kind of gauging analysis can also be used to calculate clearances between
passing trains. An example of this is seen in Fig XXX.
The minimum clearance between one train and any other object is 250 mm. This distance,
however, can be less. In the case of Ardsley tunnel, the minimum design distance is 100 mm.
This is simply because the tunnel cannot be moved, and very little extra space inside can be
created. To get this kind of leniency on the rules is called a dispensation. This has to be
agreed with all parties concerned.
For the West Coast mainline (WCML) Virgin have asked to be allowed to run new tilting trains.
Again, this has resulted in a remodelling of the ECML to accommodate the new locomotives. These
have been modelled on Clearroute for gauging purposes. The types of external factors for the
kinematic envelope are slightly different for the tilting trains. That is, the cross section
of the train has to be considered for three different conditions: upright, tilted and tilt failure.
Tilt failure accounts for the train not self-righting after passing through a curve
Finally, this kind of gauging analysis can also be used to calculate clearances between passing trains.
An example of this is seen in Fig XXX.
The minimum clearance between one train and any other object is 250 mm. This distance, however, can be
less. In the case of Ardsley tunnel, the minimum design distance is 100 mm. This is simply because the
tunnel cannot be moved, and very little extra space inside can be created. To get this kind of leniency
on the rules is called a dispensation. This has to be agreed with all parties concerned.
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