Re: aside- Bunbury St Tunnel

[mauried@commslab.gov.au (Maurie Daly)]

In article <383CC713.6BEF269E@nmit.vic.edu.au> david <david@nmit.vic.edu.au> writes:
>From: david <david@nmit.vic.edu.au>
>Subject: Re: aside- Bunbury St Tunnel
>Date: Thu, 25 Nov 1999 16:20:19 +1100



>Maurie Daly wrote:

>> >> In the case of the Bunbury st tunnel in Melb it should be possible to close
>> >> one line and lower it whilst keeping the other line open,so a alternative
>> >> route via Roto would then only involve one tunnel.
>>
>> >I bet that would be expensive, almost as much as 'daylighting' Bunbury tunnel.
>> >Al those
>> >houses to  try to aquire, bridges to build.....
>>
>> >Regards,
>> >David HEad
>>
>> Sorry , you have lost me here, why is it necessary to acquire any houses or
>> build bridges to lower the floor of Bunbury St tunnel. ?
>>
>> MD

>Sorry, thought lowering the tunnel may not be feasible,and opening it up ( as a cutting
>with bridges)may be the other expensive choice - how much lower could they go in
>lowering the tunnel and still negotiage the bridge ?

Based on the distance from the start of the tunnel to the bridge ,(about 82 
metres) we could go down by as much as 2.5 metres and still have a 1:33 grade 
out of the tunnel.
As this is a very short grade , it wont impact on train loads.
Does anyone know how much the floor will have to be lowered?,ie what is the
current clearance between the max loading guage and the tunnel roof.
As a number of other readers have pointed out though , there are a number of 
additional bridges which will be too low ,and will either require raising or 
lowering the rail bed.
No matter how one looks at this problem ,it isnt easy.
I guess the real issue is do we really need double stacking into Melb at all
given that its extremely unlikely that we will ever see double stacking into 
Sydney or Brisbane.


MD