From the state that gave a temporary terminus design at Richlands that was better designed for reversing steam trains than high frequency electrical multiple units (EMU), comes another bizarre terminus design at Kippa-Ring on the Moreton Bay Rail Link (MBRL).
|Source: somewhere on QR's website|
So what is wrong with the terminus design at Kippa-Ring (above)? Two track termini generally alternate trains between platforms. Whilst a train in platform 1 waits, a train departs and another arrives in platform 2. Then whilst a train waits in platform 2, a train departs and another arrives in platform 1. There are two critical parts of this operation. First is the time it takes crew to change ends of the waiting/dwelling train, and the other is the platform re-occupation time. The platform re-occupation time is the time taken for a train to depart a platform and for another train to arrive in the platform. This is usually most efficient when the crossovers are as close as possible to the platform. Unfortunately, in this design one of the two crossovers is 430m away from the other crossover, and around 600m away from the platform. This could add an extra minute to the platform re-occupation time. In the peak period, with a train travelling through the crossover junction every 3 minutes, this poor design significantly decreases the operating margin which is critical for on-time running.
BrizCommuter is unsure of why such an odd design is in place. Could it have something to do with broken down trains pushing other trains? Could it to be allow locomotives to run around freight/maintenance trains? Is it due to a curve in the track? Or did the track planners just have a bad day? Certainly it is not designed for high capacity running of EMUs!
So how should this terminus have been designed? As previously mentioned, for maximum capacity the crossovers should be placed as close as possible to the platforms. Scissors crossovers (such as on the approach to Ferny Grove) allow for the highest throughput as they are located in the same space as just one crossover. On the downside, the diamond crossing can suffer from track wear and tear, and also adds wear and tear to train wheels (unless switch diamonds are installed, but these can be unreliable). The next best design is a double crossover where a trailing and facing crossover are located as close as possible. Due to the location of the entrance to the sidings, and a curve in the track beyond the sidings points, a scissors crossover would be best suited for this location. The diagram below shows how Kippa-Ring should have had its track layout designed in BrizCommuter's opinion - red shows a removed crossover, and the light green shows where a scissors crossover should be located.
Oh well, this is Queensland. Beautiful one day, poor terminus track layouts the next.
Note: Varsity Lakes also has a bizarre terminus crossover layout, with the trailing crossover closer to Robina. Though at least it seems that trains can turnback in a siding to the South of Varsity Lakes as well.