Public transport

Jul 4, 2016

Will new rail lines save the planet?

The justification for a big investment like the $11 Billion Melbourne Metro isn't to save the planet (it will do very little to reduce GHGs); it's to improve transport

Alan Davies — Editor of The Urbanist

Alan Davies

Editor of The Urbanist

Traction energy associated with operation of the HCMTs represents by far the largest source of GHG emissions (56 per cent) associated with the infrastructure lifecycle of the project due to the higher energy requirements of these trains compared with existing rolling stock.
Traction energy associated with operation of high capacity trains represents by far the largest source of GHG emissions associated with the 100 year infrastructure lifecycle of Melbourne Metro due to the higher energy requirements of these trains compared with existing rolling stock

I’ve remarked before that building costly new rail infrastructure in Australia’s big cities in most cases won’t generate much mode shift from cars to public transport (e.g. see Will simply building more public transport seriously suppress car use?). The warrant for new heavy and light rail lines isn’t about climate change; rather, it’s primarily to support large agglomerations of activity like the CBD and to provide non-motorists with mobility.

The newly released Environmental Effects Statement for the $11 Billion (nominal) Melbourne Metro rail tunnel illustrates this point. The project involves connecting the Cranbourne/Pakenham Line to the Sunbury Line by constructing twin nine-kilometre rail tunnels under the CBD and five new underground stations.

Melbourne Metro will generate an estimated 543,400 tonnes of greenhouse gas during construction, assuming best practice methods are adopted. Most emissions though will come when it commences operations in 2026.

High capacity seven-car trainsets will operate on the tunnel initially (expandable to ten cars) so it will use a lot of electricity. Compared to the “no Metro scenario”, the project is estimated to generate an additional 70,900 tonnes of greenhouse gas per year in 2026. The EES expects emissions to fall to 58,000 tonnes by 2046 due to a progressively higher proportion of the State’s electricity coming from clean sources. (1)

It would be possible to reduce operational emissions – to 47,600 tonnes at 2026 and 37,600 tonnes at 2046 – by adoption of best practice methods. These would incur a cost though e.g. purchasing more expensive green power.

These are big numbers but in the context of the State’s total net emissions – 123,900,000 tonnes in 2013 – they’re very small.  The EES says the operational emissions of the project would make “a negligible contribution to regional GHG emissions” i.e. in the order of 0.1%.

On the positive side, Melbourne Metro will generate mode shift i.e. some travellers will shift from private vehicles to trains to take advantage of the increased capacity provided by the project. The EES says it will remove an additional 286 million kilometres of car and truck travel from Melbourne’s roads in 2046. This translates to an estimated saving of 74,000 tonnes of GHGs in that year.

Thus after allowing for the increased operating emissions attributable to the tunnel on the one hand, and the reduction in private vehicle emissions on the other, the project will yield a net saving in operational emissions of 16,000 tonnes in 2046, or 36,400 tonnes if best practice operating methods were adopted.

That’s a clear benefit but there’s no getting away from the fact that they’re extremely small numbers. The justification for spending $11 Billion to build Melbourne Metro – and generating 543,000 tonnes of GHGs during construction – has almost nothing to do with reducing car travel.

Much bigger gains in lowering emissions could be made by vastly more cost-effective approaches e.g. increasing taxes on motor fuel, regulating vehicle size, replacing coal-fired power stations with clean energy sources to support electric vehicles.

The key rationale for Melbourne Metro – obviously enough – is transport. It’s to provide additional capacity in the rail system to support the continued growth of the CBD and to increase network reliability by enabling all passenger lines to operate independently from end to end. Seriously reducing emissions will require much more politically difficult actions than building the occasional popular new rail line.


  1. For the purposes of this discussion I’ve ignored Scope 3 emissions (the EES says they increase 2026 operating emissions to 98,000 tonnes p.a., or 74,700 tonnes p.a. with best practice methods).
(Visited 5 times, 1 visits today)


Leave a comment

Your email address will not be published. Required fields are marked *

3 thoughts on “Will new rail lines save the planet?

  1. Teddy

    Now here’s a project that actually will reduce emissions, and allow thousands of commuters to switch from cars and buses to a low carbon form of urban transport. I expect all Urbanists to be watching Channel 7 this Thursday night!

    I don’t know if its screening in Melbourne (probably not)… Love the line that “the whole world is watching” this project. Nothing could be further from the truth actually. Even here in Sydney our Metro gets surprisingly little media attention, and hasn’t been the subject of massive whingeing campaigns or Fairfax’s trade-mark hand-wringing on behalf of property owners. And like Melbourne’s Sky Rail, quite a large section of it is on an overhead bridge.

    The only whingers are the Greens, who yet again today issued a press release attacking Sydney’s Metro. You have to wonder what “saving the environment” means to these people. And what form of public transport they actually support.

  2. Dylan Nicholson

    CO2 emissions aren’t really the main concern though, eventually all our power generation will have to be largely CO2 neutral, including the electricity used by the train network. As you say, the primary benefits are in allowing more conglomeration – i.e. Melbourne being able to support a higher density population, and there’s no question that a few million people living and working at reasonably high density is going to have less overall environmental impact than a few million people spread over a much larger area at low/medium density levels. They’re almost certainly going to be wealthier and better educated too, which makes imposing Pigovian taxes to steer us away from environmentally-damaging forms of consumption much more politically feasible (even if it still seems hopelessly far off today).

  3. Tony Morton

    It’s true Alan – the claimed reduction in per-capita greenhouse emissions per the Metro tunnel EES might as well be a rounding error. But that shouldn’t surprise anyone, given the assumptions that went into the modelling.

    I’ve looked at Technical Appendix V to the EES that details the greenhouse results. The key to the all-but-null result is Table 6-12 on page 57. PTV is assuming there will be almost _no_ increase in the number of train services provided after the tunnel opens (with the exception of the newly electrified Melton line). In other words, even in 2046 it’s supposed that trains will only run every 20 minutes beyond Dandenong and Sunshine outside peak times. As far as operations go, the entire capacity benefit is assumed to come from running the same service as now with longer trains that have fewer seats and more standing room – a change that makes little difference from a passenger’s point of view.

    Indeed it apparently gets worse. If we look at the fine print in the model data in Appendix C – specifically the second table with the modelled number of train services – it appears there’s an assumption that across all affected lines there will be _fewer_ off-peak services running when the Metro tunnel is built, compared with either the present day or with the future ‘no tunnel’ scenarios.

    Feed all this into a model like VITM – which we already know is conservative in its predictions of mode shift to public transport – and it duly repeats the assumptions back as conclusions and predicts only a modest reduction in car travel. I’d wager the modelled reduction is almost entirely confined to peak times. Certainly the reported train PKT projections in the same Appendix (which are broken down into peak and off-peak) are relatively unchanged off-peak between the ‘tunnel’ and ‘no tunnel’ scenarios.

    It’s practically certain that this is not how things are going to play out over the next three decades. But of course the purpose of this particular exercise was never to assess the mode shift potential of the Metro tunnel: as part of the overall EES, it’s to seek out potential adverse effects on climate change and any mitigation measures available. Hence the substantial sections devoted to the (very positive) new measures to be introduced to run the new high-capacity trains more efficiently, to ensure they actually reduce the net energy use per passenger. The exercise has fulfilled its criterion of success, which is to demonstrate no increase in emissions per PKT in Melbourne’s transport system – and it’s done so with some very low-ball assumptions to ensure it’s an ironclad conclusion.

    For what it’s worth, the PTUA switched from opposing to supporting the Metro tunnel on the basis that it would lead to a substantial boost in services in the west, both to provide a ‘West Gate Bridge alternative’ and to drive a big mode shift to public transport. That does require a better service plan than implied in this report – but it’s apparently not the purpose of this report to propose one.

Share this article with a friend

Just fill out the fields below and we'll send your friend a link to this article along with a message from you.

Your details

Your friend's details