Johnsonville Branch Crossings

This page documents crossings on the Johnsonville Branch during a morning peak in 2014.

The line was converted to CTC in 1998 but a remnant of the orignal Single Line Automatic Signalling remains. It is the use of yellow on the intermediate to indicate an opposing train in the next section. Crossings are scheduled and if a departure signal clears when a driver is expecting a crossing he (or she - I refuse to use the plural "they") will contact Train Control for permission to act on the light.

Safety sidings are provided on both mains at each of the crossing places so simultaneous berthing is permitted. Note that at each crossing place there is an up main and a down main; not a main and loop.

An unusual aspect of signalling at each of the three crossing places is that low speed lights on the home signals clear to the main unoccupied but not to it occupied. It would require a good deal of luck on my part to document this situation!


Up inremediate at Crofton Downs

Up intermediate signal 486 at Crofton Downs (approaching Ngaio) is displaying Clear Normal Speed, telling the driver of this morning peak up train that the Ngaio - Khandallah section is clear. In the off-peak trains are scheduled to cross at Ngaio and this signal would display Caution Prepare to Stop.




Yellow on Intermediate

Box Hill Intermediate

Approaching Box Hill on an Up service to Johnsonville 726 Intermediate signal is is indicating Caution Prepare To Stop.  On the Johnsonville Branch this can have one of two meanings:

  • The Khandallah 4R Up Home signal is at stop, or
  • The Khandallah 4R Up Home signal is at caution; the 8R Up Departure is at stop and there is an opposing train in the Khandallah - Johnsonville section.

The latter is a remnant of the Single Line Automatic signalling that was in use until 1998.




Khandallah Banner Indicator

Banner Indicator

On this sharply curved section of line 4RBI banner indicator repeats the indication of Khandallah 4R Up Home which is out of sight around the curve. The banner indicator is not a signal.

The intermediate in rear was displaying yellow and the banner indicator tells the driver that the Up Home is displaying red/yellow so there is an opposing train in the Khandallah - Johnsonville section. This was expected as a crossing is scheduled at Khandallah.




Khandallah Up Home Signal

KNH Up Home

As Khandallah 4R Up Home comes into view it is displaying red/yellow Caution Medium Speed Prepare to Stop and both up departure signals are at stop.

An oddity of Branch signalling is that the low speed light on the home signal clears to the Down Main when Unoccupied but not when it is Occupied.




Simultaneous Berthing

Berthing

As we arrive at Khandallah on the Up Main the opposing train, which is entering the Down Main, is nearly clear of the Khandallah - Johnsonville section. Both trains are moving. The up train will stop opposite the shelter. Safety sidings on each main allow this simultaneous berthing.

In the off-peak trains are scheduled to cross at Ngaio and the down train arrives first. When off-peak trains are running to time there is no simultaneous berthing.




Rural Wadestown

Wadestown

Another nicely timed crossing. As the down train approaches the south portal of tunnel 4 Lizard the Wadestown 8L Down Home signal is at caution. We had a caution on the intermediate and now a caution on the home. The opposing train has just arrived on the Up Main. We will enter the Down Main and claim the Wadestown - Wellington section. There are safety sidings on both mains so simultaneous berthing is permitted.

This rural scene is just 3km from the Wellington CBD and the Beehive (Parliament).




Last Updated: Saturday 12th April 2014

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