Before Ben Carroll MP got a Keilor East station added to the plans, Airport Rail, like what got built in Brisbane but unlike Sydney or Perth versions, threatened to be a stub with no wider network benefits.
To bolster its sorry case, the Airport Rail project must put on a marauder's hat and poach benefits that other projects (ill-advisedly for them) have not exploited.
Such benefits remain on the table due to us not electrifying Melton as early as we could have (although who knows, maybe it will still beat airport rail), not increasing all day suburban frequencies on lines such as Craigieburn to aid connectivity and not exercising the option to run Metro Tunnel every 5 minutes off-peak and thus enable CBD tram reform.
If we were to do the last with those extra paths going to Airport Rail then most of the benefits stop right there. Whereas if they go to something like an electrified Melton line then the wins ripple much further from their origin. For example the prospect of new suburban stations, relief from the Ballarat line and more balanced loads for trains entering Sunshine.
Because almost everyone sees themselves as using Airport Rail occasionally (while having some vague faith that it brings business to the state) this, like level crossing removals, has topped public polls on the popularity of transport projects (though to be fair major bus network reform has also rated well).
Melton electrification has historically suffered by its benefits being geographically concentrated. Few from Mornington or Montrose are likely to use Melton rail much. Whereas they might occasionally use Airport Rail. So despite Melton rail upgrades helping thousands of people every day it has made front pages far less than the showy but ultimately less beneficial airport rail.
However the story is not over. It's a thrilling race. Who gets the spoils of all that unlocked capacity in the Metro Tunnel first? Most would have predicted Airport Rail. But interest has ebbed and flowed.
Also the political environment has changed. There are no safe seats anymore. The Werribee by-election shocked Labor. And more recently the rise of One Nation in the polls threatens to split the non-Labor (and some of the Labor) vote in regional areas and some outer suburbs. Areas like Melton are in the box seat for some of these forces as a long-term government faces an election in barely four months.
I am often asked my opinion on various transport topics. The two hottest in the last six months have been 'free' public transport and airport rail. My answer to both are the same - both carry massive opportunity costs and there are far better uses for the money (which could fund an amazing network all across Melbourne).
I can't help thinking that some of the gloss has gone off airport rail. People realise it won't actually save very many much time relative to its cost and greater needs elsewhere. Add population growth and changing politics, I think Melton should get first dibs on funding and train paths.
Suburban Rail Loop - cheaper per interchange point?
Don't think of the Suburban Rail Loop East as an underground orbital railway for a moment. Instead think of it as six new interchange points. As far as interchange points go they are pretty good; all six are key destinations in their own right, four intersect with Metro lines, two with trams and one with V/Line.
A crude way of comparing SRL with airport rail is the cost per interchange point created. And by interchange I'm assuming one where there's access to 7 day frequent service for a standard fare.
Melbourne Airport Rail is like $12b per interchange added whereas SRL is $34.5/6 ie $6b per interchange added. SRL ends up being half the cost per interchange created.
$6b per interchange is still a huge amount of money and it is reasonable to debate the SRL's value, timing and opportunity costs. This is especially when Melbourne must create dozens if not hundreds of interchange points in the suburbs to make PT useful, a feat that is unaffordable at $6b a pop.
Especially given that Melbourne's rail network is so steadfastly radial, an SRL at $6b per interchange point that fundamentally transforms the network is better value than Airport Rail (at $12b per interchange point) which (at best) does not change the network structure and (at worst) takes core area train paths from potentially busier lines such as an electrified Melton.
One can fairly be concerned about SRL in its current form but the also expensive but even lower benefit airport rail (not to mention various large road projects) should also not escape scrutiny.
In my view there is more substance in the view that both Airport Rail and SRL are low priority than the stance, expressed by some SRL opponents, that Airport Rail should be our biggest public transport priority, when in reality it contributes very little benefit to peoples' everyday travel relative to its cost.
Whereas potential exists for a well-designed SRL to have substantial benefits but these would be even greater if a substantial package of other measures (involving a tiny percentage of SRL's cost) were done in the decade leading up to its opening.
A 5am formula - can it work for SRL?
As I mentioned before SRL could be conceived of as six linked interchange points costing $6b each to build. The connections between them will be faster than existing driving or public transport options. This speed has value in extending the range of destinations available within a given time.
Also of value is the number of interchange points. More interchange points means more origin and destinations possible. And, like how the number of handshakes in a room increases disproportionately with the number of people, the number of potential connections rises in a triangular fashion. But only to a point; have too many interchange points and they eat into each other's catchment and slow travel speed.
Merit is just a number, not a unit. The higher the better.
As an example a new line with three stations (p = 3) has an option of travelling: a. first to middle station, b. first to last station, c. middle to last station. Thus, like handshakes, there are three combinations. But unlike handshakes you can do reverse trips, which I've counted, giving a total of 6. That makes the formula simpler as there is no longer any dividing by 2 as with handshakes.
Below is a simpler version of the same formula with the speed ratio changed to a time ratio to put it in the denominator.
The merit number is 30/0.4 or 75.
While we're at it let's also replace Glen Waverley with Mt Waverley to improve directness but keep the length the same by terminating it at Doncaster rather than Box Hill.
This changes the SRL to a 10 station project, undoubtedly adding costs (unless offsetting savings can be found elsewhere). Travel time is slower due to the extra intermediate stations - let's call it 0.5. But it's still very fast.
That gives a merit number of 90/0.5 or 180, or more than double what we had before. SRL costs would undoubtedly rise with this approach but not double, meaning that an SRL option with more stations could have higher benefits relative to cost.
Anyone can dream up random formulas at 5am so I'm not going to claim this is particularly rigorous. But I think something like this vaguely makes sense when initially comparing options.
It should be acknowledged that some of the extra stations (eg Warrigal Rd) are never going to be the busy hubs in terms of land use that say Box Hill or Clayton will be. However they do provide connections with more routes, thus multiplying (not adding) travel opportunities. If one was to do a journey plan a huge number of trips would include the SRL, especially one with well planned multimodal interchanges, as one leg of it, even in cases that might not be immediately obvious. This is because its large time savings over existing buses (and for that matter driving) draw a lot of trips (including some induced demand) into it, even if an extra interchange is required.
Application for improved services
The formula isn't just useful for infrastructure-oriented megaprojects.
If you take the view that a location only qualifies as an interchange point if routes intersect at high frequency, have easy physical interchange and the geometry is sound, you will find that the vast majority of potential interchange points are hampered by low frequency and/or poor physical access.
As an example just four out of nearly 400 bus routes in Melbourne run every 15 minutes or better seven days per week during the day. That figure at night? Zero.
Compared to the SRL the number of interchange points created when you upgrade a bus (especially one that intersects with a large number of already frequent routes such as routes like 241 or 508 in Melbourne's north or 246 in the inner-east) is very high. A snowballing effect starts if you upgrade existing trains and trams as well as parallel lines become a frequent grid.
It does not require upgrades to that many trains and bus frequencies to create 60 or even 100 new interchange points, ie ten times more than the Suburban Rail Loop. And instead of the cost per each interchange point being $6 billion it is a tiny fraction of that, albeit mostly operational expenditure from running that more frequent service.
Travel speeds uplifts aren't as high but because you are upgrading so many interchange points (with so many new connection possibilities) for such little cost the scale of benefits is high (ie SRL magnitude) making it a big deal. So much so that 10 min frequencies on multiple lines and routes should be done as soon as bus and train drivers can be recruited.
Buses are not necessarily directly substitutable for the SRL but their great scalability and very low cost per improvement makes them an important part of any network development strategy. That is because we don't have the capacity to add 100 connection points through SRL like means in the next decade but we certainly can (and much more) with bus and train service upgrades. Also such network reform can complement the SRL and is arguably even necessary for the SRL to work with reasonable usage as it makes getting to its stations easier from a large catchment.
Conclusion
To summarise, something like the SRL East might be triple the capital cost of Airport Rail but it might benefit many more that in terms of the number of trips. Along with land use influences, which Airport Rail on a premium fare will not at all.
Although this is contingent on really good interchange design across all modes (people have expressed concerns about 'Cheltenham'/Southland in particular) along with bus reform and consistently frequent service on intersecting train and tram lines.
While they're very different projects to SRL East and Airport Rail, rail and bus frequency increases, and for bus network reform, a method based on interchange points and travel speed savings may still be useful to compare the merit of various network proposals.
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