Melling Branch - Operating Irregularity

Track circuiting was removed from most of the Melling Branch in 1996. The signalman could no longer rely on the Branch occupied lights for some moves. In addition there was a possible operating irregularity.

In certain situations the indicator lights at Melling could show Occupied when there wasn't a train on the branch. Conversely, the lights could show Not Occupied (and 17 signal cleared) when there was a train on the branch.

During this period Melling - Wellington trains may have operated without authority.

Note that in December 2013 new signalling using axle counters was commissioned at Petone so the situations described on this page no longer apply.

Is track occupied.

Is there a train at Melling? There may be!

A Potted History Of Melling Branch Signalling

Hutt Deviation Line.  When the Hutt Deviation Line opened in 1927 the junction was controlled from the old Petone signal box. Lower Hutt had its own interlocking.

Branch Created.  In 1954 the old line was truncated at Melling and electrified. Lower Hutt controlled the Lower Hutt - Melling section. Petone controlled the junction. The Junction - Lower Hutt section was double track.

Control Transferred To Petone.  In 1958 control of the Lower Hutt - Melling section was transferred from Lower Hutt to Petone. Junction - Lower Hutt was singled. The branch branch was fully signalled, with signals at Melling as well as at Lower Hutt.

Lower Hutt Yard Closed.   In 1983 the Lower Hutt yard was closed leaving just two signals on the branch - a Down Outer Home signal at Melling and and a Down Directing signal at the junction.

Signalling Removed.  In 1996 all signalling on the branch was removed, except for signal 78 Down Directing From Branch. A section of track circuiting in the rear of signal 78 was retained.

More Information. See See Lower Hutt signalling and Melling signalling for details of branch signalling. The relay circuits used to control Branch operation can be studied on my Melling Branch Circuits page.

Petone Signals

Operation 1996 - 2013  If a train entered the branch with 48 points normal the toggle lights turned on. If a train departed the branch with 48 points reversed the toggle lights turned off (even if part of the train was left at Melling). If a train was verballed off the branch with 48 points normal the toggle lights did not turn off.

New Signalling. On Sunday 29th December 2013 a new interlocking, operated from Train Control, was commissioned. The new interlocking included a down directing signal at Melling.

When The Branch Occupied Lights Must Not Be Relied On

EM80 & Video Test Train.

The Track evaluation car EM80 and the overhead video train (an EMU with a camera attached) sometimes run up the Hutt Valley. The usual procedure was for the train to be signalled onto the Branch. It was then verballed past 78 signal at stop onto the Up Main. Signal 17 was then cleared and the test train continued to Upper Hutt.

The toggle lights remained on so the next up Melling was verballed past 17 signal at stop and on to the branch. When this train returned to signal 78 the signalling operated as usual.

A complicating factor with EM80 was that it may not operate track circuits and so must be blocked.

Train Disabled On Branch.

If a train becomes disabled on the branch the rescue train must be verballed past 17 signal at stop and on to the branch. Once the two trains are coupled the signalling operated normally.

If it was decided to leave the disabled train on the branch signal 17 can be cleared for a third up train, even though the branch is occupied. This is because the toggle lights will have turned off when the second train exited the branch. In this situation the local instructons required that 47 points be isolated and hand operated.
The signalman must pay careful attention to the Train Register.

No authority

Did Melling - Wellington trains operate without authority?

Double Line Automatic Signalling.  Petone was operated under the Double Line Automatic Signalling Regulations. The Melling Branch was within Petone Station Limits.

DLAS Regulation 1 states:

(a) Trains must not set back after leaving a station, or run on the right-hand line in the direction of travel except:
   (i) When authorised by a Mis 60.
   (ii) When at a station and wholly within the Home or Outer Home signals movements may reverse direction on the authority of the Signalman who must first satisfy himself that it is safe for the intended movement.

Operating Procedure.  From 1996 until 2013 the operating procedure was:

  • Train signalled onto the single line branch and travelled to Melling.
  • At schedule time the train returned to the junction, without first obtaining authority from the signalman.

Unauthorised Procedure?   The operating procedure appears to be in conflict with DLAS Regulation 1.  I am not aware of any instruction that authorised trains to depart Melling without first obtaining the signalman's authority.

Missing From Local Instructions?  Maybe the following instruction was missing from the Local Instructions:

Trains may depart Melling on schedule time. DLAS Regulation 1 (a) (ii) is amended accordingly.

Not A Safety Issue. The local instructions specified that only one train at a time could operate on the Branch so the irregularity described above did not create a safety issue.

New Interlocking. The new interlocking which was commissioned on the 29th of December 2013 included a down directing signal at Melling so trains now depart Melling on a light.

Last Updated: Thursday 17th November 2016

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