By Richard W. Heine

From Summer 1978-79 Edition of N.Z. Railway Observer

The author returns to Paekakariki after many years where, as children, he and his brother spent their Christmas holidays. He recalls a week in early January 1950, and compares it to a similar week in 1977, documenting in detail the signalling and interlocking.

Part 1

It is 27 years later when I drive north from Wellington again, towards Paekakariki. Through Thorndon and under the bridge carrying the Johnsonville Line, the approaching city-bound traffic still dips into the hollow under the second span added at a later date - the hollow made necessary by steep 1 in 40 gradient on that line. Past Kaiwharawhara ( still Kaiwarra in 1950 ) and onwards to Ngauranga, the Hutt Line running signals have been changed for the second time; originally these were upper-quadrant semaphore signals ( in 1922 ), which were replaced around 1940 by the single-lens searchlight type colour-light signals, but these in turn have now been replaced by the three-lens type, which require less on-site maintenance. Along with this, the green signal glass colour has been changed from the apple green shown by the searchlight signals to a decidedly blue-green hue ( a change in the British standard for signal colours ). It’s a somewhat unattractive shade.

At Ngauranga the road leaves the shadow of the Wellington Fault scarp - which forms the western border of the harbour and presents a barrier to the Manawatu - and turns into a gorge. Looping back under the bridge connecting the two main trunk tunnels, separated by only 274m, the road is three times wider than previously, but just as steep as ever. At the crest traffic lights have sprouted, and from these a motorway now takes the through traffic around Johnsonville instead of through it. A backward glance shows that the northern motorway exit from Johnsonville is along the route of the old main line, closed in 1937. Thence the motorway follows more or less the former railway line down to Tawa ( Tawa Flat to me ) and the gorse-covered hills must surely remember the panting of an "Ab" climbing those 6.5km of 1 in 56 at an average speed of 24 km/hr with 150 tonnes strung out behind.

Beyond Tawa, glimpses of the present line show double track, right through in fact to the coastal section of Pukerua Bay. In 1950 it was single track from Tawa to Plimmerton.

More traffic lights at Porirua, and then off the motorway to rejoin what remains of the old main road north, at the eastern margin of Porirua Harbour. Along here both the railway and the road used to echo the crenulated shoreline with a diminished amplitude, the former in a succession of 10 chain ( 200 m ) radius curves that were regularly mauled by the "Ed" locomotives at their maximum allowed speed of 30 m.p.h. ( 48 km/hr ). The little swampy pockets with toi toi and bulrush between the road and the railway embankment have gone, and so has the blue heron we always looked for. The line now is as straight as a die and as uninteresting, paralleled by a half-built motorway - an ugly scar of yellow weathered clay - running through what used to be open countryside, but now being metamorphosed into urban sprawl.

Prior to the introduction of multiple-unit electric trains ( "MU"s or more popularly, "units" ), which took over almost all suburban runs on this line from 28 November 1949, Paremata station, like Porirua, was a single low platform with the usual crossing loop. However the "units" brought with them a problem in the form of their high doors, and climbing aboard from ground level when they were standing in the loop was well-nigh impossible for other than school boys. This meant that these trains could not be time-tabled to cross at either of the above stations, so within 14 months ( printed in the working timetable dated to take effect from 4 February 1951 ) a second short curved platform was added to the western or seaward side at Paremata. Although this west loop had a capacity of forty-seven 18ft 6in ( 5639 mm ) wagons, it was to my knowledge only used by the MUs.

Now the whole lot has gone, and the line runs over a new formation and bridge ( the old wooden railway bridge was a mere stone’s throw from the present narrow, two-lane concrete road bridge ). Dolly Varden became Mana when this deviation was opened in 1960, because the locals didn’t like the name. Although Dolly Varden was the name of a shop , it in turn was named after a lady of doubtful character and repute. Evidently the associations of the name proved too "quaint" for the good citizens of the locality !

From Plimmerton little is different by road or rail through to Paekakariki, except for the signalling controlling the coastal single-line section between South Junction and North Junction, both regarded technically as interlocked stations. South Junction is well known to rail travellers, in that it marks the point where the ocean is suddenly and dramatically seen 54 metres below the windows of northbound trains. The term "junction" is something of a misnomer as the only alternative route at either place is along the wrong line, but what is particularly interesting is the use of signals to enforce the permanent speed restriction on trains entering the single-line section. This is achieved in two distinct ways. ( Fig. 1 ) In November 1962 the Departure signals 8R at South Junction and 10L at North Junction were changed to double-unit signals able to give only a medium-speed indication ( red over green ), and the associated approach intermediate signals, 3132 and 3617 were appropriately modified. The second method shown in signalling and interlocking circular 1782 dated July 1976, applies only to up ( northbound ) trains which approach South Junction on a down gradient of 1 in 66. At a distance of 275 m before signal 3132, a permanent speed board ( 40 km/hr ) is erected. When a train passes this, an automatic timing device comes into operation and providing the speed restriction is observed, the trip arm of the automatic train stop device at signal 3132 is lowered, allowing that signal to show either "yellow over red" or "yellow over green" ( indicating "prepare to reduce to medium speed" ) before the train reaches it.

The approach intermediate signals 3261 and 3466 are also interesting, in that they are not block signals, i.e. their sole function is to provide an advanced indication of the aspect displayed by the home signals 8L and 10R respectively. Signal 8R will not clear ( to red over green ) for an up train until the preceding train has cleared signal 10R at North Junction. In the case of down trains, however, the single-line section is divided into two blocks by signal 3363, which is atypical in that it is an absolute and not a permissive automatic intermediate stop signal. The presence of signal 3363 reduces headway for the slower down trains, and it displays an absolute "stop" to safeguard any train that might stall in the tunnels on the section ahead from a following train moving under the "stop and proceed" rule associated with a permissive stop signal. It was installed about the time of the introduction of the "Silver Star" in 1971.

And so I arrive at Paekakariki , situated at the extreme southern end of the Manawatu Plains, where, narrowed to a few hundred metres, they run into the sea under steep cliffs. The place is know colloquially and universally as "Paekok", an abbreviation that has been immortalised in Will Lawson’s lines

A-firing on the "Paekok"

With just your trousers on.

The full name, however means the perch ( pae ) of the green native parakeet ( kakariki ). I get out of the car and stand beside the Beach Road crossing. The crossing bells clank as an "Ew" arrives, and in my mind the years roll back.