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The final run into Central Station leaves no option but to use a twelve-plus kilometre tunnel to bypass the dense urban development of inner metropolitan Sydney. All the existing corridors are both too tightly curved and at or near capacity. The eastern portal of the tunnel will surface near Redfern Station on the western side of the rail corridor, giving access to Central’s historic intercity platforms (numbers 1-10).

The western portal of the tunnel will be in the vicinity of Chullora or Strathfield. The high-speed alignment will use the pipeline easement in the Chullora Yards to link up with the Inner West Line at Sefton. This will require some pretty significant civil infrastructure to cross various roads and railways, but it keeps us above ground for far longer than any of the previous high-speed rail proposals, resulting in a significantly lower cost to access central Sydney.

Alignment design

Cost Summary

The total cost of the sector is $1.148 billion for 23.5km ($48.86m/km) – by far the most expensive sector in the entire Hot Rails network. This is no surprise – a 10km dual-track tunnel was always on the cards and was never going to be cheap, but making maximum use of existing infrastructure has enabled us to access Central Station at high speed for a lower cost than any proposal to date.

The biggest cost is obviously tunnel – both the 9.4km Inner West tunnel and the 1.1km Regents Park tunnel. Other major costs include the substantial civil works and land acquisition at Strathfield South, and the upgrade costs of Redfern and Central Stations. The terminal costs are unavoidable – there will have to be some renovation of the stations and a new control centre, although a billion-dollar rebuild as contemplated in the AECOM report is patently unnecessary. The costs at Strathfield, though high, enable the avoidance of several additional kilometres of tunnel, which results in substantially lower total costs.

Chester Hill – 5.2km

The sector begins at Carramar Station, proceeding inbound along the northern side of the Inner West corridor. The corridor already contains the twin tracks of the Inner West line, as well as the single-track South Sydney Freight Line on the southern side. There is about 15m of empty corridor between the existing tracks and the corridor boundary, which is sufficient for the 12m dual trackbed required for the high-speed line.

Villawood station will need its pedestrian crossing widened, while Leightonfield Station will probably need a total rebuild (its main building is on the north side of the tracks). Carramar and Chester Hill stations can both be passed with no modification, while Sefton Station will need a major rebuild of its pedestrian crossing.

There are also four road overpasses and two underpasses. The Horsley Drive overpass is just barely wide enough for two extra tracks (perhaps allow $2.5m for modification to be on the safe side). Woodville Road overpass requires no modification, but both the Miller Road and Chester Hill Road overpasses will need to be widened by the full 12 metre width of the new tracks.

It’d probably be polite to put noise attenuation walls alongside the corridor, at least where the new tracks will be right alongside residential back fences. After all, trains make a lot more noise at 200km/h than they do at 80.

Regents Park – 2.1km

In this section the alignment must cross a mixed residential-industrial district in order to maintain favourable geometry. From a look at Google Earth, it appears that at least 17 houses and four warehouses would have to be demolished to make way for an at-grade alignment. Houses in this area are fetching a typical price of $800,000-$1,000,000, so the cost of land acquisition would be well over $25 million. Add in the need for at least four pretty serious grade separations (up to $20 million), perhaps 1200m of noise-attenuation walls (up to $10 million), demolition, security, civil works, interruption to existing services and all the rest of it (not to mention the politics of demolishing a large part of a neighborhood) and you’re pushing $60 million, best case. It should be possible to get away with a tunnel of about 1100m in length, which would cost about $68 million. For a similar cost, this is a much superior option.

At the eastern portal, the track will curve to join the pipeline easement through Chullora. The alignment is at-grade and requires little civil infrastructure apart from a couple of grade separations (a minor one at the driveway to the Potts Hill Reservoir, and a major six-lane overbridge for Rookwood Road. Some noise barriers will be required for an adjacent residential zone, and a single decrepit industrial warehouse may have to be acquired (guess $5 million?), although it is also possible that the building is used by Sydney Water. In any case, the building is in the way and will have to be replaced. The section ends at Rookwood Road.

Chullora – 2.2km

This section begins at Rookwood Road, where a major, double-carriageway grade separation will be needed. Subsequently it uses a wide pipeline easement to pass through the Chullora railyards and industrial precinct on a virtually unimpeded at-grade alignment. All that is required are three minor grade separations to allow the railyards to continue to operate. The biggest difficulty may be avoiding the existing pipeline where cuttings are required, however the corridor is wide (40m+) and it should be possible to place the tracks adjacent to, rather than on top of, the pipelines. The sector ends at the service road to the immediate west of the Hume Highway.

There is a moderately severe change of vertical gradient at the beginning of the section, going from +2.5° in the tunnel to -2.5° in the railyards. This 5° change of grade would ideally occur over about 2200m, however the topography makes a transition length of much over 1000m impractical. The minimal allowable transition length is about 900m, which would limit operation to 200km/h (this is planned for the entire sector anyway).

Strathfield South – 2.0km

The easiest way to deal with the complicated interaction of several different transport corridors in this section is to keep the high-speed railway at-grade, and modify the existing highway and railway alignments to accommodate it. This isn’t as hard as it looks; there are already three levels to the interchange, with the Hume Highway at grade, the freight railway entrenched below natural ground level, and Roberts Road elevated on a flyover. The ideal alignment would cross the Hume Highway twice, necessitating two elevated sections of highway. These would be difficult to construct while keeping highway traffic open, so it may be necessary to completely redesign the interchange, including the acquisition of several commercial properties.

Once we get past the Hume/Robertson interchange, the alignment proceeds at-grade along the pipeline reserve, before descending below grade and entering a tunnel at the eastern extremity of the reserve. The proximity to existing development will necessitate noise attenuation walls on both sides.

Inner-West Tunnel – 9.4km

Finally we get to the most expensive single piece of the whole system – a tunnel of almost 10km in length stretching from suburban Strathfield to the switchyards of Redfern and Central Stations. There are two options, the first being for the east portal of the tunnel to be located west of Redfern and to dedicate platforms 1 and 2 to the high-speed railway. This would impinge on the capacity of the important inner-city station, so it would require that the unfinished platforms 13 and 14 be completed.

The other option is for the tunnel portal to be located after Redfern, requiring another 1.5km of tunnel costing perhaps $100 million+. This would be desirable due to avoiding disruption of suburban services, but the much higher cost means that it would probably be cheaper to make the modifications to Redfern Station. The shorter option is therefore preferred.

We also note that there is potential to co-utilise this tunnel for a future “Western Fastrail”-style service to Parramatta, Blacktown and Penrith. The service frequency on this sector of the line would therefore be far higher than the rest of the system. Also, the long length of the tunnel leads to an increased likelihood that trains will have to be scheduled to pass one another in the tunnel. It is therefore it is desirable to have a dual-bore tunnel to avoid aerodynamic pressure spikes when trains pass one another with a relative speed of 400km/h+, which could lead to passenger discomfort. While this is slightly more expensive ($74m/km as opposed to $62m/km), it allows a high degree of future-proofing for additional services, and is therefore considered a sensible option.

Redfern to Central – 2.6km

From Redfern, the existing tracks will be used into Central Station, upgraded for use with the high-speed trains. This is not strictly necessary, as the trains will be travelling at lower speeds in this section, however we shall specify upgraded track anyway to ensure minimal maintenance of the expensive trainsets. Redfern Station is assigned a high renovation cost of $75 million due to the need to complete platforms 13 and 14

Comparison to previous proposals

I’ve claimed repeatedly that the strategy of re-using existing infrastructure has resulted in a far lower cost to access Central Sydney than any previous proposal, but at $1.5 billion from Glenfield (or $1.75 billion from Campbelltown), it’s still exceedingly expensive. Exactly how much cheaper than previous proposals is it?

There have been five significant proposals for high-speed rail to Sydney in the last 25 years – the VFT, Speedrail, Arup 2001 (Howard Government), AECOM 2013 (Rudd Government), and BZE 2014.

VFT and Speedrail didn’t even bother accessing Sydney at high speed. Recognising the engineering and political difficulties of constructing such a track, they opted to either use the existing rail network for low-speed access (VFT) or place the terminal station on the city outskirts (Speedrail). Neither of these proposals therefore amount to “high-speed CBD access”.

The Howard Government’s 2001 study did not make a detailed engineering assessment of the costs to access central Sydney,

The Rudd Government’s 2013 study (AECOM) does not state the cost of the railway from Glenfield to Central (the only data in the public report are for Central to Southern Highlands – $11.1 billion). However it is not hard to work out that most of that is in the Glenfield to Sydney sector. The access scheme proposed is almost absurdly expensive, with a design speed of 400km/h all the way to Central (thus requiring extremely large-diameter tunnels), and avoiding all political complications by using a 37km dual-bore tunnel beginning at Glenfield. Just this tunnel alone would cost an enormous $5.44 billion. Additionally, a billion-dollar renovation for Central Station was specified. Add to this track costs, a control centre, maintenance depots, etc, and all told, the cost to access Sydney from Glenfield must be well over $7 billion – more than the Hot-Rails estimate for the entire Sydney-Canberra railway!

Low-carbon advocacy group Beyond Zero Emissions made several sensible adjustments in their response to the Rudd Government report. By lowering the city-access speed to 200km/h, they make cost savings in three important ways: first, a smaller tunnel diameter can be used. Second, existing rail infrastructure can be utilised to a greater degree, requiring less length in tunnel. Third, less noise-abatement infrastructure is required above ground due to the lower speed. As we calculated in an earlier post, this would result in a time-penalty of about three and a half minutes from Sydney to Glenfield. BZE claim the final 29.7km into Sydney (from Glenfield) would cost $4.2 billion, including a $1 billion renovation of Central Station. So BZE manages to save about $3 billion for a three-and-a-half-minute slower run between Glenfield and Central. But it’s still $2.7 billion more than Hot Rails.

Hot Rails Sanity Check

It’s worth asking whether the Hot Rails estimate is credible, given the substantially lower estimate to even the BZE study. Why, when BZE has a similar maximum speed within the sector, was the predicted cost so different?

Firstly, BZE specifies a billion-dollar renovation to Central and Hot Rails does not, accounting for $1 billion right off the bat. While Hot Rails proposes to use 200km/h rollingstock substantially similar to existing medium-speed services, the 350km/h rollingstock proposed by BZE is completely different to anything presently existing on Australian railways. For this reason, Hot Rails can get away with using the existing station with only minor renovations, while BZE requires a much more substantial redevelopment. But that still leaves a $1.7 billion discrepancy to explain.

Possibly, it is due to an oversight on BZE’s behalf. Tunnels are costed at a rate of about $155m/km (visually estimated from chart on page 82 of their report). This accords well with the Rudd Government study’s estimate for the cost of a dual-bore, 400km/h design-speed tunnel ($150 million). However, we note that lower speeds allow smaller diameter tunnels to be used, at an obviously far lower cost. It is not clear that BZE have accounted for this in their study; they do not state that they have, therefore it is safe to assume they did not. The methodology used by Hot Rails (based on UK construction models and a study by Worcester Polytechnic) estimates a twin-bore tunnel would cost $123 million/km for 400km/h, but only $85m/km for 200km/h. Our estimate is therefore $70 million/km lower than BZE’s, due to matching the specifications of the tunnel for the performance of the rollingstock within it.

Hot rails specifies 14.1km of tunnel between Glenfield and Central; BZE specifies approximately 15.5km (judging by the map on page 73). The costs assigned to tunnel by both studies are therefore $968 million (Hot Rails) and $2.33 billion (BZE). That alone accounts for a $1.36 billion differential, leaving a mere $340m unaccounted for. Yes, it’s a lot of money, but only 8% of BZE’s total (or less than 5% of AECOM’s). I’m happy that my estimate is plausible.

Overspecification has consequences.

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Hat tip to Lensaloft for the Inner West panorama used for the header image 🙂