BrizCommuter has for many years been calling for capacity improvements to the Gold Coast / Beenleigh Line corridor. Somewhat surprisingly, some very decent plans for a quad tracking of the Kuraby to Beenleigh section have recently been announced.
Project page - https://www.tmr.qld.gov.au/projects/logan-and-gold-coast-faster-rail
This project known as the Logan and Gold Coast Faster Rail, or Gold Coast Rail Line Capacity Improvement Project involves the construction of 4 tracks between Kuraby and Beenleigh stations. This includes faster track sections, and multiple level crossing eliminations. This could allow for a doubling of Gold Coast peak direction services from the current 6 trains per hour per direction (tph) to 12tph, and doubling of contra-peak and off-peak Gold Coast and Beenleigh Line services from 2tph to 4tph each. Wonderful idea, but with one serious problem - the Cross River Rail (CRR) 3 track bottleneck between Dutton Park and Salisbury!
The original proposals for CRR originally included a tunnel portal at Yeerongpilly, resulting in 5 tracks between Park Road/Boggo Road and Yeerongpilly stations. With additional infrastructure, this could have allowed up to approximately 36tph (in both directions) along this section, allowing for huge capacity increases on the Gold Coast, Beenleigh, and proposed Salisbury to Beaudesert Lines. 12tph of these services could have run via South Bank, and 24tph via CRR. The proposed Kuraby to Beenleigh quadruplication would have been essential to maximise system capacity, as the combined Gold Coast and Beenleigh Line services could have been allocated 24tph.
Unfortunately, the iteration of Cross River Rail that is under construction, is limited to 3 surface tracks between the tunnel portal at Dutton Park and Salisbury. This means that only 24tph can be operated in this section, to be shared between the Gold Coast, Beenleigh, and proposed Salisbury to Beaudesert Lines. All 24tph are expected to run via CRR. With 6tph allocated to the Salisbury to Beaudesert Line, this leaves 18tph for the Gold Coast and Beenleigh Line. This peak direction service could actually be operated with the proposed (and now presumably abandoned) 3rd track and platform at Loganlea, signalling improvements, some additional stabling, and an additional turnback at a suitable location on the Gold Coast Line (Helensvale would have been the most optimal site). This would have allowed for 6tph Gold Coast express services, 6tph Gold Coast semi-express services (additionally serving Beenleigh to Loganlea), and 6tph Loganlea all stations services. 4tph Gold Coast semi-express and 4tph Loganlea all stations services could have been operated during the contra-peak and off-peak.
So what are the advantages of the Kuraby to Beenleigh quadruplication, compared to the considerably cheaper (Loganlea 3rd platform) option?
- More reliability and flexibility - fewer operating constraints in this section (Loganlea turnbacks/overtaking would require close to on-time running to work).
- Faster journey times - no need for some Gold Coast services to serve stations between Loganlea and Beenleigh, plus some track straightening.
- Removal of level crossings - this is always a major safety advantage.
The big question is as to whether the considerably more expensive quadruplication is worth the funding compared to the cheaper option (Loganlea 3rd platform)? The most critical capacity constraint on the Gold Coast and Beenleigh Line corridor will still be the 3 track section between Dutton Park and Salisbury. The failure of the CRR project to have adequate tracks on this section will an Achilles Heel for SE Queensland's rail network. Using the Tennyson Loop for some trains to bypass this section is unlikely to be able to increase capacity into Brisbane as it will add multiple conflicting train movements. Additionally, it is unknown how the slowing down of contra-peak Gold Coast Line services on this section (as they may be stuck behind all stations or empty services) will be resolved.