Monday, July 6, 2020

Cross River Rail - Southside Bottleneck

BrizCommuter recently discussed Cross River Rail's (CRR) Northside bottleneck at Mayne junction. At this location, merging 6 tracks into 4.3 (the .3 is the Ferny Grove Line) may result on a net gain of zero train services that can be attributed to Cross River Rail. This won't be alleviated until Cross River Rail can be diverted onto the North West Transportation Corridor to connect with the North Coast Line at Strathpine, which doesn't seem to be on the radar of the Queensland Government.

Southside Bottlenecks 

Unfortunately, there are also multiple major bottlenecks on the Southside, the worst of which is the "not fit for purpose" limitation of 3 tracks between CRR's portal at Dutton Park and Salisbury. In the Bligh Government's Cross River Rail Mk1, the tunnel ran to Yeerongpilly, allowing for 4 tracks south of Park Road/Boggo Road. Unfortunately the destructive Newman Governments's BaT Tunnel shortened the tunnel to Dutton Park, with only 3 tracks south of the portal, the same as at present. Properties purchased for resumption under CRR Mk1 were sold, making it harder to re-purchase. When the Palaszczuk Government replaced the BaT with "cut price" Cross River Rail Mk2, the portal remained at Dutton Park, with the same 3 track constraint.

There are also bottlenecks along the Gold Coast/Beenleigh Line corridor due to the line having 3 tracks between Salisbury and Kuraby, and 2 tracks between Kuraby and  Beenleigh.These are visited later in this article.

The Problem with 3 Tracks
Rail Operations 

The problem with 3 tracks is that it only allows express trains to overtake all stations / stopping trains in one direction. In the opposite direction, express trains can get stuck behind slower all stations trains. Whilst the rail operations plan for CRR is a closely guarded secret, it is assumed that it will be a choice of two am peak period operating paradigms:
  1. Split - From the South approx. 12tph Gold Coast and 6tph Beenleigh peak services will run through CRR, and 6tph Salisbury/Beaudesert Line services will run via South Bank. From the North approx. 12tph from either Caboolture of Kippa-Ring will run via CRR, and 4 to 6tph will run from a Northside destination to Salisbury/Beaudesert via South Bank.
  2. All via CRR - From the South approx. 12tph Gold Coast, 6tph Beenleigh, and 6tph from Salisbury/Beaudesert will run via CRR. From the North a combined 24tph from Caboolture and Kippa-Ring will run via CRR. 
Contra-peak/off-peak services are expected to comprise of 4tph Gold Coast, 4tph Beenleigh, and 4tph Salisbury/Beaudesert services. The Gold Coast and Beenleigh services will run express from Dutton Park to Salisbury, and the Salisbury/Beaudesert services will stop at all stations taking 6 minutes longer to traverse this 3 track section.

The inner-Beenleigh Line Problem
The 3 tracks between Dutton Park and Salisbury will not cause a problem in the peak direction and off-peak in the near future. However, in the contra-peak direction, it is a major problem. All trains travelling South from CRR in the am peak have to run as far as Clapham Yard, just south of Yeerongpilly. Thus with the "Split Paradigm", this single contra-peak track will need to handle 16-18tph. With the "All via CRR Paradigm" the single contra-peak track will need to handle up to 24tph, the maximum capacity of this track! Unfortunately, a single express service eats up 3 of these track slots. The result of this is as follows:
  • Up to 16tph - trains will need to have extended dwell times at Boggo/Park Road for correct sequencing and/or reduction in express running.
  • 17-20tph - trains will need to have extended dwell times at Boggo/Park Road for correct sequencing and/or reduction in express running. A 4th platform at Salisbury is required. 
  • 21-24tph - a 4th track is required between Dutton Park and Salisbury, otherwise express running will not be possible. 
Unfortunately work has already started on this section, and urgent project changes will be required to add the 4th track to the design and build (note: 4 tracks, but only 2 platforms are required at most of these stations). The failure to build 4 tracks will result in contra-peak train services being slowed down by up to 6 minutes. It would mean that there would not be consistent clockface timetables between contra-peak and off-peak services. There may also be long term peak period capacity constraints when the demand on this rail corridor exceeds 24tph.

Poor project management and cost cutting has resulted in a 3 track layout between Dutton Park and Salisbury, that will slow down train services from Day 1 of Cross River Rail. 

The 3 track sections needs an urgent redesign
The Outer Beenleigh Line Problem
There are currently 3 tracks between Salisbury and Kuraby which allows peak direction overtaking, but only 2 tracks between Kuraby and Beenleigh (expect for Bethania inbound). It is expected to that in the am peak CRR will handle 12tph from Gold Coast, and 6tph from Beenleigh. For any peak increase over 8tph Gold Coast and 4tph Beenleigh services, there needs to be infrastructure improvements.

In the contra-peak and off-peak, then assuming 4tph Gold Coast and 4tph Beenleigh Line services, the trains will need to overtake on this section. This is most likely to occur at Loganlea, though the exact location depends on the sequencing of Gold Coast and Beenleigh Line services on the Dutton Park to Salisbury section (note: based on the existing timetable they would overtake at Altandi). Thus there are two upgrade options:
  • Triplication from Holmview to Kuraby, 4 tracks/platforms at Loganlea, and improved turnback/stabling facilities at Beenleigh. This would be more expensive, but not slow down Gold Coast express services,and would be more reliable.
  • Curtail the Beenleigh Line to turnback facilities at Loganlea (3rd track and platform for turnbacks, plus a siding to buffer 4tph counter-peak vs 6tph peak direction frequencies). All off-peak, and 50% peak Gold Coast Line services would stop at all stations between Beenleigh and Loganlea. This would be cheaper, but would slow down some Gold Coast express services, and will be less reliable than the previous option.
Beenleigh may need a redesign

Salisbury to Beaudesert Line
The Salisbury to Beaudesert Line (also known as the Flagstone Line) is a beneficiary of extra track capacity due to CRR. This will run along the interstate train line corridor at join the Beenleigh Line near Acacia Ridge, south of Salisbury station. A grade seperated junction would eliminate any conflicting train movements. As this line may not be open at CRR's inception, then turnback facilities will need to be provided at, or south of Salisbury station, and with a design to avoid conflicting train movements. Unfortunately CRR's plans stop at Salisbury, and it is unknown how this junction and turnback facility will be designed. 

Other alternatives
Fast regional rail would allow for faster train services between Brisbane and the Gold Coast, possibly by building an elevated train line along the M1 corridor, and plugging into the Gold Coast Line around Yatala where an interchange with the (extended by one stop) Beenleigh Line could be constructed. Unfortunately CRR has not been designed with any tunnel stubs to allow this to be connected, so it would be easier to plug this line into the via South Bank Line at Park Road. There is no funding for this plan, but if it was somehow expedited, it would reduce the requirement and cost of adding extra tracks on the Beenleigh Line. However, given that this is probably decades away, then it should not prevent the required capacity enhancements mentioned in this article.

There is also the possibility of extending the CRR tunnel to Yeerongpilly or Moorooka in the future to bypass most of the restrictive inner-City section, however this would be expensive and result in the closure of CRR for at least 6 months to allow for the extended tunnels to be plugged in.

So what is required?
Cross River Rail is currently a $5.4b tunnel being build between two bottlenecks. To avoid long term capacity issues that will be difficult/expensive to rectify, the following design changes are urgently required:
  • Provision for a 4th track between Dutton Park and Salisbury.
  • Tunnel stubs for North West Transportation Corridor (Trouts Road Line) at Roma Street. 
To maximise track capacity on the Gold Coast, Beenleigh, and Salisbury/Beaudesert Lines, so as to maximise use of CRR, the following is also required:
  • Grade seperated junction at Salisbury, with turnback facility at Acacia Ridge. 
  • Beenleigh Line upgrades between Beenleigh and Kuraby. 

1 comment:

  1. I do not think there is any hope of any of this occurring. Our current State Labor Government has said no to a new Cultural Centre underground station and so that really does give another repeated clue as to its priorities.

    Do the least possible at all times in regards to public transport, and if it can not be delivered during our term in office, then it is a no go.

    I can not help but use the example of the Kippa Ring line, which took about 100 years to build and they still stuffed it up.


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