Dublin - Metrolink (Swords to Charlemont only)

A Dub in Glasgo

https://www.boards.ie/discussion/comment/121935681#Comment_121935681

The official name is whatever is used in the design and those design documents will be finalised well before construction starts. Of course, there is nothing stopping people calling it something else

bk

https://www.boards.ie/discussion/comment/121938401#Comment_121938401

The official name of a station can change at any time. See Heuston Station, formerly Kingsbridge Station or Connolly Station was originally "Dublin Station", then renamed to Amiens Street Station before being renamed to Connolly.

Of course ideally best to get it right at the start. I'd call it Glasnevin or Cross and Guns, Brian Boru is a terrible idea IMO.

dambarude

https://www.boards.ie/discussion/comment/121938199#Comment_121938199

This is enormously helpful, thank you Coyote. Thanks to all the other posters too for their thoughtful replies.

According to those documents, the house I'm looking at will have a LASmaxdB(A) groundborne figure of 35 when operational. This is like double dutch to me, but from what I can gather it would be perceptible. Just how perceptible is very hard to imagine...

Sam Russell

I think 35dB is not loud and is a quiet room - perhaps a slow fan might be the level. You will not notice it - certainly after a few months.

You heating system will likely be louder.

bk

https://www.boards.ie/discussion/comment/121938954#Comment_121938954

If you have an Apple Watch, it has an app called "Noise" which can measure the current noise level. You can also get apps for iPhone and probably Android that do the same.

35dB would be perceived as almost complete silence by most people. In my living room, with very well insulated walls living in a quiet estate, far from a road, the watch measures 34dB while iphone app 38dB. Heating would be louder then either. I'd perceive all this as basically silence or normal background noise. A whisper is about 30dB, a normal conversation about 60dB.

If you were living close to a road, there would be more noise from it. Few people in Dublin would have a background noise floor less then 35dB. You should try the apps yourself to get a feel for it.

Coyote

https://www.boards.ie/discussion/comment/121938954#Comment_121938954

Hi Dambarude

just to double check the linked pdf has 3 listed LaSmax on each page the first is "Construction - TBM" then "Construction Excavation" and last "Operation"

the one for you to look for long term would be the Operation number (column 12 from the left)

Air borne and Ground Borne noise are not the same, 45 dBa would be very quite for air borne noise but very loud for Ground Borne noise. low frequency is more rumbling noise and can be picked up by people differently.

35 is at the "Lowest Observed Adverse Effect Level" but how much of an affect I can't say, HS2 reports it as low probability of adverse comment

below is from the Melbourne Metro Rail Project

https://bigbuild.vic.gov.au/__data/assets/pdf_file/0013/51106/MT-Technical-Appendix-I-Noise-and-Vibration-Appendix-B-Part-1.pdf

and this is from HS2 in the UK

https://assets.hs2.org.uk/wp-content/uploads/2018/10/19140016/Control-of-ground-borne-noise-and-vibration.pdf

HS2 reports a low probability of adverse comment but the Metrolink will be running at High frequency of trains, it will run every 90 seconds at peak time.

not sure any of that helps in deciding if it's a problem or not, but at least you have more info to think about

dambarude

https://www.boards.ie/discussion/comment/121939709#Comment_121939709

Thanks again for the helpful replies.

I've double checked and the column is indeed 35 LAsMaxDBa for operation. The VDV day is 0.009 and the VDV night is 0.005. The VDV scores seem well below perceptible levels, if I'm interpreting it correctly.

I'm not sure if 'low level of annoyance' or 'Lowest Observed Adverse Effect Level' is worth the risk!!

CatInABox

https://www.boards.ie/discussion/comment/121940197#Comment_121940197

I know that it's a personal thing, and different people have different levels of tolerance for these things, but honestly, 35db is nothing.

Are you annoyed by light rain? Or the sound of a quiet library? Because they're about 40db.

timmyntc

https://www.boards.ie/discussion/comment/121940301#Comment_121940301

Airborne and groundborne noise sources are perceived very different, much lower dB of groundnoise can be very difficult to ignore compared to airborne noise

Not all 35dB are created equal

dambarude

https://www.boards.ie/discussion/comment/121940301#Comment_121940301

I wouldn't be concerned with that level of noise in the context of rain/a library, where it is somewhat random and ebbs and flows.

Thinking out loud - my concern would be that the noise, albeit low, would have a very different 'vibe' when experienced at regular intermittent periods (e.g. every 90 seconds, every 180 seconds).

Again, very grateful for thoughts on this - thanks!

Sam Russell

Mod: The question of ground noise has been answered so can we move on, please.

Sam Russell

Just as a point of interest.

Can the Metro trains be configured to run on the 750VDC that Luas uses? If not, what advantage does the higher voltage give? Could the Metro trains be configured to be dual voltage?

L1011

https://www.boards.ie/discussion/comment/121940774#Comment_121940774

Probably not, allows more power draw for faster acceleration, probably not.

bk

https://www.boards.ie/discussion/comment/121940774#Comment_121940774

Yes, Metro trains can run on 750V DC, the Copenhagen Metro uses that, though third rail, rather then overhead.

I'm actually not sure what Metrolink will use, I haven't found it in any of the docs! I know some people have commented on 1,500V DC, but I think they maybe getting it mixed up with DART. I think Metrolink may end up using 750V DC as it is quiet common for similar Metro systems.

L1011

https://www.boards.ie/discussion/comment/121941010#Comment_121941010

Metro North was to use 1500V DC, the various Metrolink documents comparing to international systems are to 1500V DC systems; the off-the-shelf rolling stock will be 1500V DC - I'd be amazed if its not 1500V DC. Copenhagen Metro units are Luas-sized (39m).

bk

https://www.boards.ie/discussion/comment/121941031#Comment_121941031

Please point me to this in the Metrolink docs so? Because I haven't found conclusive evidence.

BTW Metro systems all over Europe use 750V DC, I can think of a dozen such systems off the top of my head.

You may well be right, but I want actual proof.

bk

https://www.tce.co.in/case_study/metro-rail-electrical-system/

The most widely used voltage level for Metro Rail traction system globally is 750V DC. This system has been used in the metros of UK, New York, Singapore, Paris, Beijing, Kolkata, Bangalore, Dubai etc. Mainly DC traction voltage was being used earlier, but with advancement in technologies, many metros have adopted 25kV AC system recently. 25kV AC is used in Delhi, Chennai, Jaipur, Hyderabad, Seoul, Paris and Hongkong.

L1011

https://www.boards.ie/discussion/comment/121941038#Comment_121941038

This has one direct comparison to Sao Paulo for instance:

https://www.metrolink.ie/media/vlip2lpw/metrolink_pr_design_development.pdf

750V DC overhead schemes are generally legacy; third rail is generally super-legacy (the safety concerns are immense), but there are odd exceptions of recent enough complete new builds using it, like Copenhagen.

A larger unit like we're going to have here on 750V DC would be significantly constrained.

bk

https://www.boards.ie/discussion/comment/121941058#Comment_121941058

So nothing conclusive.

The is Metrolink document looks at both 750V DC and 1,500V DC projects around the world.

https://www.pleanala.ie/publicaccess/EIAR-NIS/314724/5_EIAR/Volume%205%20Appendices/Chapter%2012%20Electromagnetic%20Compatibility%20and%20Stray%20Current/A12.4%20MetroLink%20DC%20Field%20Intensities%20at%20Dublin%20Airport.pdf?r=807639

A larger unit like we're going to have here on 750V DC would be significantly constrained.

65m isn't large. London Underground runs on 630V DC and has much longer vehicles.

Amsterdam Metro is also 750V DC and one of the lines has 120M long trains!

bk

BTW digging, further, Metro North was also specified to use 750v DC and the New Metro North analysis doc specificies either 600v or 750v DC. Both TII docs.

Metro North 750V DC:

https://www.railwaygazette.com/four-bids-to-build-dublin-metro-north/33848.article

The standard gauge line will be electrified with 750 V DC overhead, and will have 17 stations.

New Metro North study (basically the precursor to Metrolink):

https://data.tii.ie/metrolink/alignment-options-study/study-1/metrolink-concept-engineering-design-report.pdf

Electrical power to the vehicles is mostly supplied through overhead lines called catenaries, which are in contact with the trams’ pantographs. The traction power supply distributes a direct current (DC) at a voltage of 600V or 750V.

Now neither of these are conclusive for Metrolink. But in both cases they were going to use 750v DC for longer 90m long vehicles

L1011

https://www.boards.ie/discussion/comment/121941113#Comment_121941113

London Underground has significant performance issues due to the low voltage, and has increased to 750V DC where possible already. I believe when the NTFL is introduced they will be 750V DC entirely. 750V is inappropriate for the size of vehicle that will be in use here.

In particular, air conditioned vehicles are going to have a particularly limited performance envelope on 750V DC. I seem to recall the Amsterdam Metro doesn't have aircon, but it has been quite some time since I was on it.

Metro North included detailed proposals for replacing the transformer equipment on the Green Line to handle the higher Metro voltage. Your article there is not a TII document and has blatant inaccuracies - high floor metro vehicles being interoperable with Luas?

bk

https://www.boards.ie/discussion/comment/121941261#Comment_121941261

Again, Metro North was going to use 750v DC, please see the above documents.

That isn't to say that upgrades wouldn't be required to substations, but that doesn't change the fact that Metro North was going to use 750v DC.

L1011

https://www.boards.ie/discussion/comment/121941285#Comment_121941285

An otherwise visibly inaccurate article on a magazines website is not a RPA (no TII back then) document.

Everything I remember from the time period stated 1500V DC.

bk

https://www.boards.ie/discussion/comment/121941291#Comment_121941291

The New Metro North document above is a TII document.

L1011

https://www.boards.ie/discussion/comment/121941301#Comment_121941301

And doesn't refer to the original Metro North.

This is utterly pointless anyway. If it turns out they go for 750V DC on Metrolink - the only system that's actually potentially going to happen - they're idiots.

bk

https://www.boards.ie/discussion/comment/121941291#Comment_121941291

I'm afraid you are misremembering (or maybe mixing it up with DART). Here is the TII document for Metro North:

https://www.tii.ie/tii-library/railway-orders/eis-metro-north/EIS%20Metro%20North%20Volume%201%20Book%201%20of%201%20Part%201%20%28Chapters%201%20to%2010%29.pdf

On page 71:

A 750V DC overhead traction power supply;

L1011

https://www.boards.ie/discussion/comment/121941314#Comment_121941314

I misremembered then

Point that TII would be idiots to go for a constrained voltage still stands, the RPA were idiots back then too clearly.

EVBusFan

In the Metrolink Railway order, in Volume 2 of the EIAR Chapter 04 (Description of the MetroLink Project) Section 4.12.3 (Proposed MetroLink Grid Connections and Power Systems) has some information.

"""

4.12.3.2 Traction Substations

[...]

The substations will be supplied from the MV ring (20kV AC) and will include traction power 

transformers and rectifier units which provide the DC voltage and current to distribute to the traction 

power system. Each traction substation will have two 20kV / 2x1.25kV 3.3MVA transformers and two 

1500V DC 3MW rectifiers units.

All traction supply substations at the stations will have the same type of equipment. Some equipment 

will be at ground level and others underground depending on the type of station (surface, retained cut, 

and underground). 

4.12.3.3 Traction Power System

The traction power system is DC, which is converted from an AC power supply, which enables trains to 

move on the network through a catenary system which is rated at 500VDC.

[...]

"""

It seems to only reference 1500VDC and 500VDC which based on the single occurrence I suspect is a typo

bk

https://www.boards.ie/discussion/comment/121941316#Comment_121941316

BTW even S-Bahn in Berlin, their equivalent of DART, uses 750v DC

bk

https://www.boards.ie/discussion/comment/121941325#Comment_121941325

Thanks, the mystery deepens!

500V DC is also possible for a Metro, but as you say it could also be a typo.