Sunday 11 June 2017

Otago Central Railway [28A]: Omakau

Omakau was at 178.56 km from Wingatui and its importance developed from becoming the railhead for two years during 1904-1906. It remains a service centre for the area and the station remained open until the line closed in 1990. Omakau's relative prominence in railway terms can be seen by the size of the station building provided, which was similar to the ones at Ranfurly, Alexandra and Clyde.

Geographically Omakau is near the top of a long climb from Alexandra that steepens at Chatto Creek and requires the zigzagging ascent of the Tiger Hill to surmount. This accounts in part for the provision of an engine depot at Omakau in steam days as engines would need to be changed and serviced. The other part is the location of Omakau at the foot of the climb to Wedderburn referred to in the posts about Lauder and Auripo. In earlier years engine crews were based at the depot but they were moved away in 1930 and after that time the facilities gradually disappeared. A lot of stock traffic originated from Omakau and even in the dieselisation era trains were originated from there until the traffic began to fall away in the 1960s.

After reading D&E again I found that the turning triangle at Omakau dates from 1935 and it replaced a turntable. So indeed, the turntable at Omakau was an NZR installation, not just something from the construction era as I had thought (not being aware of that information in the book before now). The same section records that the triangle was closed in 1968 which was the time that the line was fully dieselised with DJ locomotives that did not need to be turned (the older English Electric DH locomotives that ran from the mid 1950s if operated singly did need to be turned).

Overview of Omakau.

 Starting from the east end we have the engine depot area and there were two distinct forms. The turntable and two engine sheds appear on the chainage charts and the turntable was in use until 1935 when the triangle replaced it. Whilst the track layout as always is a guess, the tracks would have been altered when the triangle was put in and the turntable was ripped out, but the exact position of different tracks at different times in relation to each other isn't exactly known. It may be that on the final map I just get it to display two different layouts as I can do this with the Qgis query system.

There was only one engine shed in later years and eventually it was removed, probably when the DH locomotives started running in the mid 1950s as they were allowed to operate through to Clyde. The triangle was still used with the English Electric locomotives as they needed to be turned when operating singly. When the DJs came into operation in 1968 they did not need turning so the triangle was closed after that time.

Omakau had home signals and "gainstroke" levers were used. These were different from the familiar frame levers that we are all used to and are shown in one of the photos below. The signalling was taken out of use in 1984.

Coming up the east end of the yard we can see the stockyards at far left, a row of houses across the bottom of which one still exists today, another house for the stationmaster at the top and the station, goods shed, loading bank and various other facilities. The diagonal siding behind the goods shed was used to load stock and ballast trains. Of interest is that the loading bank follows the alignment of this siding and so is somewhat unusual in general layouts of stations.

The main station platform, goods shed and loading bank are the key remnants of the station to be found at the site today.

 Here is the gainstroke signal lever frame at Omakau on 16 September 1989. As can be seen a key difference is that the chain attached to the signal wire passes through the top of the lever instead of being attached to the bottom and this is done to get maximum pull distance. This was a necessity in locations like Central Otago where wide ranging temperature extremes were experienced and thus the expansion and contraction of the mechanical linkages affected the operation of the mechanical semaphore signals. (Ophir, which is 3 km from Omakau, recorded a temperature of -21 degrees C in the winter of 1995) Behind the platform is the cemetery.

 Omakau yard still had all its tracks in place when this photo was taken, but the goods shed is hidden from view behind the train. Dr George Emerson talks to the train crew as we wait for a section clearance returning from Clyde to Wingatui on the "Photographers Special" excursion of 16 September 1989.
A view looking down the platform from the western end. At extreme left is a gangers shed (still there today) and at left behind the platform is the toilet. One of the OETT's then-new "scenic" cars can be seen in the right foreground on the train.
At the eastern end of Omakau.

 The former engine depot area.

 Coming in to the main area of the station from the east.

The passenger platform and goods shed.

 Where the signal frame was that we saw in one of the live photos above.

 Goods shed and loading bank.To the far right we can see the one remaining railway house.

 Gangers hut at the west end of the platform.

 Western end of the yard looking east. At extreme right is a buffer stop for the stockyards siding.

 Bridge No. 74 over Thomsons Creek opens out at the far end into a cutting through an isolated rocky outcrop.
 As the line climbs to the Tiger Hill summit another set of rock cuttings are passed at 113 miles.

 Approaching the summit cutting, the road went over the top of the cutting originally but was diverted to a level crossing somewhere in the foreground until the 1960s. Then the bridge 74a was built to carry the highway over the top of the cutting .

 As the grade descends towards Chatto Creek it enters the Tiger Hill via this series of rock cuttings.

 A gangers hut at the entrance to the first horseshoe curve. The line turns through 180 degrees to descend the hill in the background and comes out in the middle of the picture before turning away to head into the distance.
Entering the second big curve which takes the line through 130 degrees to curve left across the background in this picture as it heads down to Chatto Creek.