Petone Re-Signalled

During a Christmas 2013 Block of Line a new computer based interlocking was commissioned at Petone. On this page I document the re-signalling project.

(Right)   The dummy signal used by the signal sighting committee.

dummy signal

Scheme Plan 2012

Copies of the scheme plan were circulated to staff in late 2012.
As construction proceeded it became apparent that there were some significant changes from the scheme plan. I will document the actual configuration when I have the final S&I.

Control of Interlocking

The interlocking will be controlled from the NTCC using Realflex.

Down Trains

Down trains passing 201 or 205 signal at Petone will be automatically described as ex "Hutt" or "Melling" and the description indicated to A Box to confirm train order ex Petone.

Up Trains

Up Trains on the Wairarapa Line from A Box will be described as "Hutt" or "Melling" by the A Box train describer. The description will be indicated at Petone. Realflex automatic commands will be provided to set the route for Hutt and Melling trains at 214 signal.

Train Ready buttons will be provided on Petone Up Platform for stopping train crews to indicate their route if necessary.

The Beginning Of The End

The beginning

At the end of January 2013 contractors interested in bidding for the Petone re-signalling contract walk through station limits. They were protected by Rule 918 Foul time. For details of how the signalman applied protection see my blocking page.

Note that this was under the 25/11/08 version of the Track Safety Rules. In the Alternative Track Safety Rules, introduced in Wellington at the end of 2013, this procedure became Rule 908 Blocking.

The Signal Sighting Committee

Sighting committee

On Thursday 25th July 2013 the signal sighting committee checks the position of pole mounted 213 Down Directing from Up Main signal. This signal will replace 68 ground light.

19th Century Protection

19th century technology


Pre-cast manholes

In August 2013 pre-cast manholes appeared through-out Petone station limits. This is the Normandale overbridge between Western Hutt and Melling.

Signal Location

Signal location

15th August 2013 - a peg marks the location of pole mounted 213 Down Directing from Up Main signal. This signal will replace 68 Shunt and Down Starting from Up Main ground light.



On Friday 16th August contractors were busy installing ducts and pre-cast manholes south of Petone Box. Note the signal bases.

Pulling In cables

Pulling In cables

On Thursday 3rd October 2013 contractors pulled in cables at the 11.5Km peg.

Wiring Signals

Wiring Signals

On Sunday 27th October contractors wired these two Up Directing signals. Note the axle counter transducer.

Standby Power

Standby power building

The building housing the standby power plant has been placed on its foundations. Next to it are the foundations of the main location. The Melling Branch is in the foreground. Photo taken on Saturday 2nd November. Photo taken from SH2.

Safety Siding

Safety siding

Saturday 2nd November - the new safety siding on the up main at Melling Junction. This siding was not shown in the scheme plan. Photo taken from SH2.

Old and New

Old and new

Wednesday 6th November - Old and new side by side.

  • Searchlight and LED signals.
  • Fxed mast (with ladder) and folding mast
  • Insulated joint and axle counter.

Recording the New Asset


Wednesday 6th November - The new asset is recorded by the ubiquitous GPS receiver. The contractors are working under Rule 917 Individual Train Detection (ITD) with an observer. The observer is the person with the yellow box.



Thursday 7th November - One of a number of large cabinets that have been installed at Petone. Labels on the small white boxes suggest that they contain the switches for lock-out controls. The vehicle and cable were on site for much of the day without much apparent activity. I suspect that a fibre optic cable was being jointed.

This photo shows two examples of new technology eliminating jobs - digital technology is about to make the Petone signalman redundant and the NZ Post Te Puni Mail Centre (mail truck parking area across the road) is to close because of falling snail mail volumes.

Signal Returns To Melling

Melling Signal

After an absence of 17 years a signal and train detection (in the form of an axle counter) return to Melling. The Melling platform is just out of sight on the left (vegetation prevented me from including it in the frame). SH2 is in the foreground. This signal was not shown on the scheme plan. Photo taken on Friday 8th November 2013.

Main Location

Main location

The main location has been placed on its foundations. I believe that the building was delivered with the equipment pre-installed. Photo taken on 17/11/13 from the adjacent State Highway 2.

Ballast for the Safety Siding


A truck reverses in the commuter car park before backing to Melling Junction with a load of ballast for the safety siding. The car park occupies part of the former Petone rail yard. Several years ago State Highway 2 was moved closer to the railway - it now also occupies part of the former rail yard. Photo taken on 18/11/13.



Hands clear! We have checked the continuity of the wire and now the tester at the Loc is checking insulation resistance with a meggar. Every wire must be tested - and by more than one person. Maybe power will be turned on at the Loc in a few days and the signal illuminated? (Unfortunately I may be working at Taita Box for the next few weeks so I may miss seeing the signal illuminated for the first time). Photo taken on 19th November 2013.

Draft S & I

In late November 2013 a draft S & I diagram was released, with significant changes from the scheme plan.

Patone Draft

Safety Points. 277 safety points on the up main will allow a train to be signalled up to the junction while a second train has been signalled from the Branch.

Melling Signal. The signal at Melling was removed in about 1996 and the practice (until Petone Box closed) was for an up train at Melling to change direction and return to the junction without the permission of the signalman. I am not aware of any instruction authorising this procedure. 203 signal will ensure that a train departs Melling only when it has the permission of the signalman.

Starter & Director. 214 signal is classed as starting to the main and directing to the Branch.

Gantry Mounted Signals. 206 (was 10) and 209 (was 74) signals are gantry mounted. The S&I suggests that the existing searchlight signals (or an LED equivalent) will be retained - presumably until new gantries are installed.

Restricted Speed lights are installed on 212, 214 and 215 signals. Is this a prelude to the introduction of the Automatic Signalling Rules?

Lower Hutt. Lower Hutt is still a network location, with a footnote that the Regional Council's designation is Western Hutt

Signal Lit

Signal Lit

Signal 213 Down Directing from Up Main was lit for the first time on 3rd December 2013. This signal will replace 68 Shunt and Down starting from Up Main.

Rule 43 states that colour light signals not in use must

  • have the light units covered, or
  • have the light units turned away at right angles to the track to which they apply so that no confusion can arise.

Signal Test Train Number 1

Signals Test Train number 1

On Saturday 7th December 2013 Signals Test Train Number 1 ran to allow the new Petone signals to be videod for training purposes. After the 0805 unit ex-Wellington had passed the new signals were temporarily raised and illuminated for the test train.

The maintainer has raised signals 210 Up Directing from Up Main (left) and 212 Up Directing to Melling Branch; Up Starting to Up Main (right). In the foregound is existing signal 14 Up Starting from Up Main, which is showing a proceed indication. The Compulsory Stop Boards protect work on the new safety siding at Melling Junction. Note that 212 signal has a fixed-red top unit (not illuminated) and a route indicator (B - Branch; U - Up Main). The video train also ran on Friday the 13th of December.

Final Measure Up

Final measure up

A wheel is used for the final measure up. A tape was also used. Will these be the dimensions that appear in the hand-sketch and Signalling and Interlocking circular? The Alternative Track Safety Rules recently came into use so protection is provided by Rule 908 Blocking rather than Rule 918 Foul Time. In practice the procedures followed by the signalman are identical. Photo taken 12th December 2013.

Eliminating Insulated Joints

Bypass IJs

In the 1950s era signalling the left rail on the down main was used for AC track circuits with insulated joints (centre); the right rail was used for DC traction return. The new signalling uses axle counters (right) so the left rail has been converted to traction return. In the weeks leading up to cutover the bonders drilled holes and installed studs for the bonds that will by-pass insulated joints. On Thursday 26th December, after Petone Box was decommissioned, the bonds were installed. Photo taken on Sunday the 29th December 2013.

Check Signal Aspects

Check signals

The aspects displayed by 212 signal and its associated route indicator are checked. Note the rusty rails. Photo taken on Sunday 29th December 2013.

Signals Test Train

Signals test train

Signals Test Train 66 sets back on the up main past the closed Petone box. It will make a fast run through station limits on the up main. The test train was testing signal sighting, clearances and axle counters. Photo taken on Sunday 29th December 2013.

First Down Melling Service

First Melling Service

Scheduled services were first signalled by the new interlocking on Monday 6th January 2014 after a Christmas/New year block of line. Train 5613, the 0635 Melling - Wellington service, has just become the first scheduled train in seventeen years to depart Melling on a light.

Train Control

Train Control Screen

The Petone panel has been replaced by this screen, a keyboard and a mouse.

Last Updated: Friday 23rd May 2014

Validated by HTML Validator (based on Tidy)