Line Capacity increase measures examined?

[dw54]

This post complements my other post asking about "microblock" signalling and "following on".

To the knowledge of those here, has LU formally examined two methods for reducing the impact of heavy loading and platform crowding on total line throughput (tph) and hence capacity:

1) Double-sided platforms - with one variation on the theme dedicating one side for waiting pax, so exiting pax have a clear platform on the other.

2) Bifurcation - where two platform tracks are provided for each approaching track. While one train is stationary at a platform, the next train runs into an adjoining platform road (ideally they should be either side of an island platform waiting area, even if double-sided).

[Side remark: You all know what it's like with an UP-DOWN-UP-DOWN configuration and a cross-over on the approach to your station. I used to commute from Leagrave, and the then BedPan 317s had a wonderful tendency to approach on the Up Fast, and crossover to the Up Slow just before entering the platform. Over the bridge we'd all go!!! ]

Of course, stations like Earl's Court and Edgeware Rd have the layout of a bifurcated station, but are also either a junction or a terminal. So the question is, has there been a conscious process of examining the benefits of bifurcation and double-sided at the present mission-critical stations whose dwell times effectively dictate throughput and hence line capacity?"

Cheers

David
Perth, Western Australia

[Chris M]

Well Tower Gateway on the DLR has recently been rebuilt with a double-sided platform with one side for boarding pax and one for alighting pax.
A second westbound platform is under construction at Stratford, and although I don't know how they will be arranged, the geography of the station leads me to suspect that both will be used for boarding and alighting (the southern (new) platform for easy interchange with the Jubilee and DLR, and the northern (existing) one for cross-platform interchange with westbound NR services into Liverpool Street.)

Regarding point 2, Leytonstone has two westbound platforms, both of which can be accessed by trains from either branch. This isn't quite what you are talking about, but it is the closest I can think of on the current system.

[dw54]

Actually, inasmuch as Leytonstone allows a train from Epping to be loading, without holding up a train via Newbury Park, it is bifurcated. The bifurcation comes as much because it's a junction. I don't think it's one of thnose places whether the loading and platform crowds lead to long dwell times, however.

Cheers

David

[Deleted]

Either bifurcation or double-sided platforms would be extremely expensive to install from scratch. On the low-level tubes, the cost of enlarging station tunnels to take another line, or building another platform tunnel, would be prohibitive in view of the fairly minor benefit obtained. Even on the surface lines, the price of land in London is such that I can't see how any cost/benefit analysis could lead to approval for such a project.

[dw54]

At some locations, there is space available, an accident of history. But for most locations where such interventions can overcome capacity limitations, yes indeed. But given that line throughput delays are generally caused by extended dwell times at perhaps 3 -6 stations per Line (would love some stats, if they are not made secret by the PPP), a lot cheaper than a Crossrail, JLE or even resignalling to Seltrac.

In isolation, as a rough postage stamp calculation, we might see a lift from 28tph to 33 tph with double-siding. Certainly, safety and the public sense of safety would be enhanced. With bifurcation, my guess is that the theoretical line capacity with current electro-mechanical fixed block signalling and manual train control, 40 tph could be approached. Put the two together, add micro-block signalling to less busy stations, and we could see as much as 37-8 tph, 35% increase over 28tph. While no substitute for Crossrail 1 and 2, for capacity enhancement on as many critical routes as possible, etc, it sure can help. A 35% increase in capacity at 10% or less of the cost of a new line would probably have a better chance of standing up to Social CBA than new lines. So, would you prefer to wait for Crossrail 2 or have a closer look at investments that fine tune the existing infrastructural investment.

Cheers

David down under