Here's some more details of what to expect from the track layout after the Easter 2013 blockade.
Five maps, showing the new layout running from west to east, complete with signal locations and routings
The first one shows the layout at the Tilehurst end, and shows the temporary Whitehouse Junction which is where the current formation is slewed northwards, so that the main lines run roughly where the relief lines currently lie and the relief lines roughly where the old goods lines used to lie. This will enable work to begin on the west end viaduct and other grade separation works.
The second one shows where the middle entrance to the new traincare depot will be located.
The third one is where things start to get interesting. The new west end of the station with new crossovers and the new platforms 12/13/14 and 15. Several things to note here:
1) Platforms 1 and 2 remain unchanged.
2) Platform 3 closes (temporarily?).
3) Platform 7 will take up its new role as the usual platform for services from London heading down the Berks & Hants to Bedwyn and the West Country (though platforms 8/9/10 could also see trains heading in that direction).
4) Platform 8 changes from the current up main platform to the down main loop platform usually handling express trains heading for the west, and acting as a reserve platform, as well as quite possibly for some of the reversing
XC▸ services from/to the South Coast.
5) Platform 9 becomes the down main platform which will be used for the majority of express services heading towards the Didcot direction.
6) Platform 10 becomes the up main platform, with the trains that currently use platform 8.
7) Platform 11 will close as a bay platform and then be reconstructed as a through platform after Easter 2013. When it reopens it will become the up main loop platform. Until that time, I should imagine that platform 9 will act as the 'reserve' up main platform, with the new relief platforms also used, but this is the only real temporary weakness in the new layout that I can see.
8 ) Platform 12 opens and becomes the down relief platform
9) Platform 13 opens and becomes the down relief loop platform.
10) Platform 14 opens and becomes the up relief loop platform.
11) Platform 15 opens and becomes the new up relief platform.
12) I should imagine that platforms 12 and 15 will handle most of the through relief line services, with platforms 13 and 14 dealing with the London to Reading terminators and reversing XC services.
13) This map also shows the new east end connection to the new depot.
14) All through platforms are bi-directionally signalled, and you can deduct from the junction indicators that there is a lot of flexibility built into the system, with more to follow when platforms 3 and 11 reopen.
Map 4 shows the east end of the station. Again much to note:
1) The underpass to the southern lines opens and is known (provisionally) as the 'up and down low level' line. Trains can be routed from/to platforms 13/14 or 15 from this line. Trains from/to the southern lines can also be routed from/to platforms 7/8 and 9 (and platform 10 at a later date) by using the current spur line as now, as well of course using the dedicated platforms 4/5 or 6.
2) Trains from the down main and down relief can access any of the through platforms either by using the crossovers at Kennet Bridge Junction (where work to reconfigure has just started), or from signals located on 'Gantry 1' at the east end of the station.
3) Future track, crossings and signal routings can be seen, including a less conflicting routing from platform 9 (in the up direction) to the up main.
The final map doesn't show much to be honest, though the junction indicators on the signals in the down direction show how all platforms can be accessed.
All in all this just confirms what we'd been told would happen, but it demonstrates just how it will happen. The amount of work that has gone in to produce such a flexible layout is commendable, not to mention the fact that it is and will be constructed whilst this station remains fully open. So far, so good!