|
|
| Re: Crossrail gets Treasury backing (was Re: London's five-year plan) (10834) | |||
 |
|||
| Home > SubChat | |||
|
[ Read Responses | Post a New Response | Return to the Index ] |
|
||
|
Re: Crossrail gets Treasury backing (was Re: London's five-year plan) |
|
|
Posted by David Fairthorne on Thu Oct 21 00:35:17 2004, in response to Re: Crossrail gets Treasury backing (was Re: London's five-year plan), posted by Rail Blue on Wed Oct 20 17:06:59 2004. Thanks, R.B., for that very clear and thorough explanation.Option I would have two major, if relatively short sections of new tunnel. I doubt if Gracechurch Street is wide enough, and who knows what lies beneath it, but if possible the tunnel from Monument to the Shenfield line portal should be built by the cut-and-cover method. Then it could emerge alongside Liverpool Street station in Bishopsgate, or even inside the station itself. Otherwise you would need extended ramps to reach the necessary depth for large diameter tubes. To descend 50 feet at a gradient of 1 in 30 you would need 1500 feet, so you would have to start at Mansion House, and much of that would be near the surface and would have to be cut-and-cover. I don't know if that would be feasible anywhere in the City because the streets are so narrow and property values are so high. Option II would be cheaper, but doesn't adress the fact that the District is underused. Nor does it provide that useful short cut from Liverpool Street to the District line. There is a third option, in which the tunnel connection to the Shenfield line would start from Aldgate East, and the Shenfield line would be served by both Metropolitan and District. Tunnelling in the east end should be easier and cheaper than in the City. Services under Option I: Services under Option II: Those look like off-peak tph, and you would probably want to increase them in the peak hours. Tube Prune says that the Metropolitan has 30 8 car tph and the District line has 30 6 car tph in the central area in peak hours. I forget how long the District line stations are, but the Shenfield line has 8 car platforms and needs 8 car trains. |
|
|
|