Saturday, October 26, 2019

Cross River Rail's Achilles Heel - Part 1 - Beenleigh Line Constraints

Back in July, BrizCommuter wrote about the multiple existing system constraints that may affect Brisbane's Cross River Rail (CRR) achieving the proposed service pattern, and preventing future capacity increases. These were:

  • Lack of 4th track between Dutton Park (CRR portal) and Salisbury 
  • Lack of 4th track between Salisbury and Kuraby
  • Northside capacity constraints
  • Lack of tunnel stubs to allow for Trouts Road Line/North Western Transportation Corridor
  • Lack of enhanced train turnback facilities at Salisbury, Kippa-Ring, Kuraby, Manly, and Beenleigh 
  • Lack of duplication of the Cleveland Line 
  • Multiple "dangerous" Level Crossings 
  • Lack of Trains and Drivers
In this article BrizCommuter looks at one of the more concerning constraints, the lack of tracks on the Beenleigh/Gold Coast Line corridor. 

The proposed am peak service pattern shows the following expectations around the Dutton Park (Southern) Portal for CRR:
  • 18tph Inbound into CRR (12tph from Gold Coast, 6tph from Beenleigh)
  • 7tph Inbound via South Bank (7tph from Salisbury, eventually Beaudesert Line) 
  • 12tph Outbound via CRR (12tph presumably from Caboolture/Sunshine Coast)
  • 7tph (presumed) Outbound via South Bank 
There are proposed to be just three tracks (and platform faces at all stations) between Salisbury and Dutton Park. This is one less running track than the original plans for CRR where the tunnel surfaced at Yeerongpilly. In the am peak direction (Inbound) the via CRR and via South Bank services will be expected to use seperate tracks between Salisbury and Dutton Park to allow the ex-Beenleigh and ex-Gold Coast services to run express, and the ex-Salisbury/Beaudesert services to service all stations. Unfortunately, as there are only three tracks then 19tph Outbound services - formed from 12tph services via CRR, and 7tph via South Bank will have to share a single track. This will cause issues as the express services will get stuck behind the all stations trains. Only 4tph of these might be expresses heading to Beenleigh and the Gold Coast (see a later section as to why just 4tph), and the rest are likely to be slower all station services to Salisbury/Beaudesert, or empty trains heading to stabling at Clapham near Moorooka. A mixed bag of 18tph express and all stations services running along this section is likely to be a scheduling and reliability nightmare. The lack of 4th track along this section is a major Achilles Heel that will severely limit adding additional train services to the Gold Coast, Beenleigh, and Beaudesert Lines in the future. It is also concerning that some of the station designs between Dutton Park and Salisbury appear to make it difficult to add a 4th track when required. Turnback facilities at Salisbury and provision for a grade separated junction at Salisbury for when the Beaudesert Line opens also need consideration. 
Not much room for a 4th track at Dutton Park
Unfortunately, this isn't the only major capacity constraint on the Beenleigh Line corridor. You may have noticed the lack of proposed off-peak services patterns on CRR's website. Well, that is because it could be quite embarrassing for the authorities involved with CRR. There are only three tracks between Salisbury and Kuraby. This means that the express Gold Coast services can only overtake the all stations Beenleigh Line services in one direction, not both. This was the reason for the Beenleigh Line services being axed during the 2018 Commonwealth Games. Without a 4th track along this section (which based on the current timetables would ideally be in the vicinity of Altandi) then the Gold Coast and Beenleigh Lines may be limited to just 2tph each, the same as at present. This somewhat defeats the purpose of building a $5b+ tunnel! It may be possible to run a combined 6tph service by adjusting stopping patterns, or more by slowing down Gold Coast Line services, but that is far from ideal. 
The problem with 3 tracks
There are further capacity or reliability constraints between Kuraby and Beenleigh and at Beenleigh station. There are only two tracks on this section, with a passing place in the Inbound direction only at Bethania which is currently used in the am peak. Without track enhancements, this section may struggle to reliably handle any more than 8tph Gold Coast and 4tph Beenleigh Line services, compared to the proposed 12tph Gold Coast and 6tph Beenleigh Line services. Additionally the current track layout at Beenleigh has limitations, in particular with trains entering service from the sidings in the am peak. To retain the current 2 platform layout, then ideally the track layout would need to be re-arranged to place multiple sidings in-between the Gold Coast Line tracks. The multiple level crossings on the Beenleigh Line also need to be grade-separated to improve system reliability. 

So to conclude - changes required for the Beenleigh Line corridor to optimise CRR train services are as follows:
  • 4 tracks between Dutton park and Salisbury (with the enhanced station designs altered to allow this to occur)
  • 4 track sections between Salisbury and Kuraby
  • Grade separated junction at Salisbury when the Beaudesert Line opens
  • Turnback facilities at Salisbury until the Beaudesert Line opens
  • 3 track sections between Kuraby and Beenleigh
  • Track layout / stabling reconfiguration at Beenleigh
  • Grade-Separation of level crossings on the Beenleigh Line
A further article will look at the other major "Achilles Heel" for CRR - Northside constraints. 

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