Tunnel Drainage

[The Snap]

Hi all,

One of my University assignments while at work is about drainage systems in tunnels; specifically, the design, construction and/or maintenance of surface water drainage for railway tunnels.

Can anyone offer any information with regards to the design, construction and maintenance of tunnel drainage systems in terms of photographs, technical drawings, technical data (such as discharge capabilities, crossfalls) etc?

Any information would be greatly appreciated!

[FYI, I will be writing the report on brick-lined tunnels and NOT London Underground or concrete-lined/segment tunnels.]

 

[Domeyhead]

You will find this one of the most challenging and interesting case studies :-

The Severn Tunnel: Its Construction and Difficulties (1872–1887) by Thomas A. Walker ISBN 1-85026-014-1 (1st edition 1888) reprinted edition 2004, Nonsuch Publishing Ltd, Stroud, England ISBN 1-84588-000-5. (Walker was the contractor entrusted by the chief GWR engineer Sir John Hawkshaw with rescuing and completing the tunnel after the 1879 flooding).

 

[Ploughman]

Tunnel drainage normally found to be in the 6ft and always in the way of diggers and dozers when relaying.
Roof drains are sometimes found which intercept water ingress through the roof and often to be found around the base of vent and blind shafts. These collect the water and channel it down the sides sometimes feeding into a pot collector drain in the cess. One of the benefits of this system is a slight reduction in icing but only slight.
Normal crossfalls of 1 / 30 to 6ft with regular spacing of catchpits as usual about 30m.
Due to the often slightly tighter 6ft mini catchpits are common but especially on heavier loaded routes they and the standard CPs both suffer from collapse due to sideloading from the trains. Circular tend to work well but many of the original brick built CPs outlast them all, until clobbered by a dozer.
Drain size will depend on local conditions with regard to rock type and overlying ground. As you may know some tunnels are bone dry and others, sometimes the next one down the line 1/4 mile away can be soaking.
Drain depth may be substandard due to original builders not digging deep enough and do you want to risk digging it deeper? Possibility of undermining or collapse.

Bramhope tunnel on the Leeds Harrogate line is a mix of conditions being both wet and dry depending where you are. However the main drain is actually a large culvert running the full length of the tunnel this runs full bore 365 days of the year with little or no variation in flow rate due to the amount of water stored in the overlying rock.

Some tunnels have a problem with fines and silt in the system. Brotherton Tunnel near Ferrybridge is one such. In the cutting outside are a number of large 6ft diam concrete drain shafts. We emptied these using a local sewer contractor and a jetvac. 10 ft of silt from each one and more in the pipe work between. 3 years later they were full again.

 

[The Snap]

Tunnel drainage normally found to be in the 6ft and always in the way of diggers and dozers when relaying.
Roof drains are sometimes found which intercept water ingress through the roof and often to be found around the base of vent and blind shafts. These collect the water and channel it down the sides sometimes feeding into a pot collector drain in the cess. One of the benefits of this system is a slight reduction in icing but only slight.
Normal crossfalls of 1 / 30 to 6ft with regular spacing of catchpits as usual about 30m.
Due to the often slightly tighter 6ft mini catchpits are common but especially on heavier loaded routes they and the standard CPs both suffer from collapse due to sideloading from the trains. Circular tend to work well but many of the original brick built CPs outlast them all, until clobbered by a dozer.
Drain size will depend on local conditions with regard to rock type and overlying ground. As you may know some tunnels are bone dry and others, sometimes the next one down the line 1/4 mile away can be soaking.
Drain depth may be substandard due to original builders not digging deep enough and do you want to risk digging it deeper? Possibility of undermining or collapse.

Bramhope tunnel on the Leeds Harrogate line is a mix of conditions being both wet and dry depending where you are. However the main drain is actually a large culvert running the full length of the tunnel this runs full bore 365 days of the year with little or no variation in flow rate due to the amount of water stored in the overlying rock.

Some tunnels have a problem with fines and silt in the system. Brotherton Tunnel near Ferrybridge is one such. In the cutting outside are a number of large 6ft diam concrete drain shafts. We emptied these using a local sewer contractor and a jetvac. 10 ft of silt from each one and more in the pipe work between. 3 years later they were full again.

That is superb, thanks! I was in the tunnels between Oldham Werneth and Oldham Mumps yesterday and the collapsing of the catchpits in the 6ft was very evident - like you say, side load from trains doesn’t give them much chance, particularly with the small distance between the two tracks and the pit itself.

 

[dalmahoyhill]

Haymarket north tunnel (Edinburgh) has just been electrified. part of the work my geotech colleagues undertook was an inspection of the tunnel lining. all i can pass on is what they mentioned to me anecdotally. I don't have any technical details.

The tunnel is a mix of cut and cover and excavated. The cut and cover sections understandably leak more. that has been bulging and some voids from long term ingress behind the lining which has been grouted up.

anecdotally much of ingress historically was contaminated by sewarage leaking from pipes coming crossing over the tunnel. This has been addressed.
The north tunnel is slab track but the south tunnel is ballasted (will need to confirm that statement)

I understand the biggest problem with drainage is in princess street gardens between the tunnel and waverley station. The line is below the natural lowest point of the gardens and excavated from what was the noor loch. All the surface water run off gravitates towards it and it has flooded numerous times.
Network rail has put sub ballast drainage with sumps to pump out the water. I don't know where it gets pumped too, probably the surface water drainage system.

 

[Xenophon PCDGS]

Tunnel drainage normally found to be in the 6ft and always in the way of diggers and dozers when relaying.

Drain depth may be substandard due to original builders not digging deep enough and do you want to risk digging it deeper? Possibility of undermining or collapse. Bramhope tunnel on the Leeds Harrogate line is a mix of conditions being both wet and dry depending where you are. However the main drain is actually a large culvert running the full length of the tunnel this runs full bore 365 days of the year with little or no variation in flow rate due to the amount of water stored in the overlying rock.

Was the matter of the Bramhope tunnel, being over two miles in length, with the conditions stated by you here, gone into in much depth when the Leeds-Harrogate-York route was being considered for tram-train operation as part of the original Leeds tramway proposals.

 

[Ploughman]

I couldn't say.
All I know is last time I was in there before the last renewal about 10 year back I got soaked fro water raining in.
It was an absolute sod trying to find good sections of rail to weld closures into for rerailing.