Tuesday, January 12, 2010

Train Air Con

As always with me, a little knowledge is a dangerous thing, but let me express my views on train and tram air conditioning.

As the temperature rose to 43 degrees today and trains failed one after another, we are told by Metro Trains that the Comeng train air con system was not designed to operate above 35 degrees. We were told this by the previous company Connex. We have been told this by the state government. Temperatures of 35 degrees plus happen every summer in Melbourne, so I am not sure why they would not be 'designed' to cope.

While the controls of an air con unit can be quite a complex piece of electronics, the basics are not. You have a compressor and a fan. Compressed gas gets cold and a fan blows through the cold area and blows out cold air into your room or vehicle, car, train, bus or tram.

The size of the compressor and the ability of the fan to distribute the cool air should be matched to the the size of the area cooled and the conditions of the area. Clearly a moving vehicle with opening doors and full of people will need to get more cooling than a a single room in a house.

Melbourne's Combino trams, the newer ones that operate in St Kilda Road and Swanston Street very obviously have inadequate air con systems. If you listen carefully on a warm day, you can hear the system cut in and out. If you listen on a hot day, you will not hear the system cut out and yet the tram is uncomfortably warm. Inadequate air conditioning. Trams with air systems designed for Germany do not have appropriate air conditioning for Melbourne.

Adelaide also bought new trams four or so years ago. They too were Euro designed and had inadequate air conditioning. Passengers were blamed for not having eaten breakfast and fainting. Remedial work was done, haha, putting heavier tinting on the windows. Eventually the government bit the bullet and spent millions on upgrading the tram air conditioning. Adelaide has bought even more new trams and retired its very old fleet. I will bet that their newest trams do have adequate air conditioning.

I have not been on one of the French trams, the Citadis that also operate in Melbourne, on a really hot day, so I can't speak for them, except that on a warm day, they seem ok.

Melbourne's B class trams, the older articulated trams have excellent air conditioning. It is a bit noisy but also easy to hear when it cuts in and out. Even when the weather is quite warm, it still cuts out at times, and yet the tram remains deliciously cool inside.

Our trains, of the three different main types, are very comfortable with working air con. The older Comeng trains are the ones with air con that is 'only designed to operate' up to 35 deg.

Back to the tech. In a big area that has inadequate air conditioning, the compressor will just work non stop. That is, it is running at full capacity and can do so for a long time, until it is either switched off or the weather cools down. If it runs non stop, it will wear out more quickly than if it was cutting in and out at regular intervals, but that is a long time.

This is what they are designed to do. That is, run for long extended periods. I just cannot possibly imagine why these Comeng train air conditioners keep failing and after being in service for such a long time, a fix for the problem hasn't been found without an expensive upgrade.

I am afraid I just do not believe the phrase, 'designed to operate up to 35 degrees'. I would believe 'designed to cool efficiently up to 35 degrees'.


  1. Hmmm, the Comeng trains didn't start falling apart in the air-con dept until a few years ago long after Melbourne had regular heatwaves and days over 40 degrees.
    Somewhat like those possums who didn't start blacking out whole swathes of suburbs until the SEC disappeared down the plughole...

  2. Anonymous11:18 pm

    Bring back the old carriages when you could open the windows of the and get a breeze blowing through on those hot days. These days if the aircon is not working you ride in a bloody furnace - no wonder people faint everywhere.

  3. "They too were Euro designed and had inadequate air conditioning."

    Euro-trains aren't much better when it comes to dealing with the cold either, it seems, as the amount of 'em breaking down in the chunnel this last couple of weeks testifies.

  4. Anonymous9:21 am

    Hi Andrew,

    The 35 degrees design is a quite convenient half truth for everyone I gather. We probably had a bit of everything: Connex failing to do required (perhaps not paid for) overhaul/maintenance/improvements to the units, and the public authority not willing to admit they were not ready to pay for it.
    This side of the truth is that these units could be upgraded at a much lower price than what they are currently testing but then someone would ask why wasnt done before, so its easier and PR-friendly to get 'new' ones. Metro will not complain either as is getting new units rather than refurbished ones so there you are....
    Technically, there are plenty of ways to reduce the failure rate of these aircons without so much fuss about it, yes you will not be freezer cool in a 45+ degree day but would be enough.


  5. I wish I had some figures at hand to back up what you say Jayne. I certainly can't recall failures like that before in hot weather, which we have always had. That overload of the system knocked peoples power out for such an extended time is outrageous. Do the private power companies employ one fixer each?

    While I like aircon Anon, you are right. All added equipment makes vehicles less reliable.

    Yep Brian. I had a laugh to myself the other day when I learnt that England's steam trains kept right on plowing through snow. I had a mental picture of a steam train towing a stranded Eurostar train out of the tunnel.

    Thanks Katx, very much as I suspected. And what about these sagging lines where spare trains are stored? I would have thought such overhead would be high priority. No use having spare trains if you can't get them out of storage because the wires have sagged.