Not this topic, but re Metro West (Sydney to Westmead), the final
independent review report:
https://www.sydneymetro.info/media/document/38211
Tony P
On Thursday 7 December 2023 at 11:08:11 UTC+11 Tony Galloway wrote:
> I reckon studying a metro tunnel for about 50 metres would tell you all
> you need to know.
>
> Tunnels in any form are not interesting scenery.
>
> Tony
>
> On 6 Dec 2023, at 18:50, TP histor...@...> wrote:
>
> I'm familiar with the old types of tunnels from walking tours and riding
> in the end cabs and the whole public can study the metro tunnels from the
> trains! However, if the Airport LIne tunnel is a two-track tube for double
> deckers, I can understand how the tunnel clearances would be tight.
>
> Tony P
>
> On Wednesday 6 December 2023 at 16:12:35 UTC+11 Tony Galloway wrote:
>
>> None of the original tunnels (inc North Sydney and ESR) had walkways, you
>> walked on the track against the direction of traffic, watching the train
>> approach warning lights that gave you 90 seconds to get to an alcove. It's
>> mostly single track tunnels, the only double track tunnel of any length is
>> between Wynyard and Circular Quay.
>>
>> AFAIK all metro tunnels are single track so comparing them to the Airport
>> Line isn’t applicable - the smaller diameter single track tunnels would
>> have a bigger gap between the side of a train and the tunnel wall than the
>> larger diameter double track Airport Line tunnel.
>>
>> And also, AFAIK the metro walkways are for evacuating stalled trains, I
>> can’t see anyone entering a metro tunnel while trains are running. If
>> passengers need to be cleared from a stuck train on the Airport Line they’d
>> walk the down them adjacent track to the next station after holding all
>> trains.
>>
>> Tony
>>
>> On 6 Dec 2023, at 14:15, TP histor...@...> wrote:
>>
>> It would be interesting to know the bore diameter of this tunnel,
>> compared with the metro tunnels, which have a walkway. It reminds of all
>> that palaver years ago about the metro tunnels being too small for double
>> deckers. So they're presumably smaller, yet they have a walkway?
>>
>> Tony P
>>
>> On Wednesday 6 December 2023 at 14:01:58 UTC+11 Tony Galloway wrote:
>>
>>> The same problem would exist with single deck stock, even narrow stock
>>> like U sets.
>>>
>>> The double deck cars occupy virtually the same dynamic envelope as SD
>>> stock, the underfloor equipment filling the space that the lower deck
>>> occupies on DD stock.
>>>
>>> With a circular tunnel the only way you’d get a walkway in would be to
>>> make the entire bore larger.
>>>
>>> Tony
>>>
>>> On 6 Dec 2023, at 12:01, TP histor...@...> wrote:
>>>
>>> I'm getting the picture that the Airport Line tunnels were not built "on
>>> the cheap", but because they decided that the technology had progressed
>>> sufficiently to build future rail tunnels using TBMs which have the
>>> advantage of lining the tunnels as they go and, judging by the metro lines,
>>> seem to be quicker than using roadheaders etc, then having to line the
>>> tunnels. The downside for double deckers of course is their vertical
>>> dimension as you say. That may have contributed to not being able to have a
>>> walkway inside the tunnel as the metro does, but as was mentioned above,
>>> they might have decided that, if work was required inside the tunnel, they
>>> could reroute trains onto the Illawarra surface tracks. I wasn't involved
>>> in the project post-approval so I have no insight into what happened
>>> subsequently.
>>>
>>> Tony P
>>>
>>> On Wednesday 6 December 2023 at 09:36:11 UTC+11 Tony Galloway wrote:
>>>
>>>> It still has to meet standard structure/loading gauge clearances, but
>>>> the round tunnel shape, of which about 15-20% is taken up by the track bed,
>>>> means the tunnel walls are closer to the trains where the roof meets the
>>>> sides of the cars, and lower where the fish bellies of the double deckers
>>>> are close to the track.
>>>>
>>>> With this tightness there are no safe spaces for anyone on track where
>>>> two trains are passing.
>>>>
>>>> Tony
>>>>
>>>> On 5 Dec 2023, at 22:44, TP histor...@...> wrote:
>>>>
>>>> If the line was tunneled with TBMs, resulting in lined tubular tunnels
>>>> like the Sydney metro tunnels, I imagine that this would create a tighter
>>>> clearance for double deck trains. All previous Sydney railway tunnels had
>>>> vertical walls. Am I correct?
>>>>
>>>> Tony P
>>>>
>>>> On Tuesday, 5 December 2023 at 19:49:57 UTC+11 Tony Galloway wrote:
>>>>
>>>>> The type of tunnel construction precluded having refuges, and with the
>>>>> alternative route through Sydenham available, diversions were the easier
>>>>> option if anything failed in the tunnel.
>>>>>
>>>>> Apparently.
>>>>>
>>>>> Tony
>>>>>
>>>>> > On 5 Dec 2023, at 17:14, Matthew Geier mat...@...>
>>>>> wrote:
>>>>> >
>>>>> > On 5/12/23 16:59, Robert Taaffe wrote:
>>>>> >> When the airport line was designed it was intended that it would
>>>>> never be maintained under traffic, only at night or during possessions.
>>>>>
>>>>> >
>>>>> > So the assumption was that things would only break on schedule ?
>>>>> >
>>>>> > Actually given the state of some of the Sydney Citadis already, I
>>>>> think that thinking is being applied to them to.
>>>>> >
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