Deviations in the Pichi Richi Pass

Part 1

The original construction of the railway through Pichi Richi Pass in 1878–79 saw a track consisting of light 40 lb/yd wrought iron rail laid with curves as tight as 5 chain (100 metre) radius. Almost immediately the poor quality 40 lb wrought iron rail caused problems resulting in an early program of re-railing with 41 lb/yd and 50 lb/yd steel rails.

Also, commencing in the mid-1880s, a number of deviations were constructed in the period up to 1891 to ease the 5 chain curves to a minimum of 7 chains. This occurred in all but three locations where the terrain and adjacent track geometry prevented this easier arrangement. The remaining locations where curves are less than 7 chains are curves 23 & 24 (at the 241 mile, behind French's farm) with composites of 6.9 and 7, and 6.94 and 7 chains respectively. Also curve 30 (near 242¼ miles), the tightest remaining at 6.5 chains, and curve 67 (247¾ miles) on the Saltia side of Saltia Bridge at 6.75 chains. It is interesting to note on the re-railing diagrams that the radii of curves were quoted as decimals, rather than fractions. This is because one chain is broken up in to 100 links, hence for example 6.75 chains instead of 6¾ chains.

In the somewhat limited and isolated research that I have managed to undertake over 30 plus years, I have never discovered any official plans or drawings of the deviation works, so the information provided is based on field observations of remaining earthworks, abandoned structures and a few very old photographs.

There would appear to be eight different locations where realignments occurred, and possibly a ninth. This ninth location is the most debatable as it is the smallest and involves no remaining structures to confirm the original route. It may have been the first undertaken as it is the closest to Port Augusta at curve 85 near the 249¾ mile post. The suspicions are aroused by two remaining features. Firstly, the current 9 chain curve puts the top of the shallow cutting right on the southeast fence line, and secondly the northwest side of the current track alignment shows an extended area within the cutting excavated to the full depth. If there is one characteristic in the original construction, where the only tools were hand tools, it was that there was never any over digging! Or was it just a minor construction error or survey error?

So we have a section where the track centreline deviates significantly from the general centreline of the railway reserve as defined by the fence lines and an area of unnecessary(?) excavation. It really would be good to unearth some original plans of deviation works to resolve this one.

One of the better known and more clearly defined locations is the dry stone wall between the two cuttings near the S Bend Bridge, as numerous early photographs have appeared showing the reconstruction work in progress or views of the area shortly afterwards.

Neither the stone wall nor the cuttings are original. In fact the deviation is quite long and starts right at S Bend Bridge (curve 36) and continues to the Woolshed Flat end of curve 41; a distance of half a mile between the 243¼ and 243¾ mile posts. The original alignment swung out around two spurs and has been effectively lost by the current sealed road alignment as can be seen in the photographs. At this location alone, this required tens of thousands of tons of extra earthworks only a few years after opening.

The other locations, three near Saltia, one between the 20 foot bridge and the Lattice Bridge and two near French's Bridge will be described in a future article.

Part 2

In this second part, I can now confirm that only eight deviations were proposed.

A chance conversation with member Richard Atkinson alerted me to a document registered in the collection of the National Archives in Adelaide which might provide some answers. A hasty visit to the reading room in Leigh Street revealed a very long parchment roll plan, with distances measured in miles and chains from mileage 00 at Port Augusta, not from Adelaide via Terowie and Quorn.

I was hoping to see the layout of the original route, i.e. curve radii, tangent points, lengths of straights and curves etc., i.e. a plan view of the original route, so I could compare it to the existing. This was not to be. The roll plan showed hundreds (probably! — I didn't count them) of faint pencilled cross sections, spaced at regular intervals, of the proposed earthworks for the eight deviations in Pichi Richi Pass. The earthwork cross sections show the estimated cut and fill profiles required to construct the new formation through the natural ground surfaces. The proposed works relative to the original formation could be clearly seen, and the new route being generally shorter in distance, resulted in slightly steeper grades in the deviated sections. As expected, the new formation levels were noticeably higher than the existing levels at the midway point of each deviation.

Notes on the sections detailed requirements for new culverts and pipes or extensions to existing ones where the proposed works were close enough to blend into the old. Further notes indicated that surplus material from Deviation No. 2 was to be used as fill material at Deviation No. 5, further along the route, suggesting that construction was planned to be consecutively from No. 1 through to No. 8. The Archives have listed the roll plan as “SA Railways Port Augusta to Government Gums line.....proposed deviations” and Deviation No. 4 between 13 mile 44 chains 18 links and 13 mile 60 chains 90 links is the first deviation recorded on the plan.

Interestingly, the position of proposed Deviation No. 2 from 9 mile 78 chains 13 links to 10 mile, 19 chains 53 links places it at Curve 79 between the 249 and 249¼ posts, but no evidence exists of the railway undergoing a deviation at this location. This curve is recorded as 7½ chain radius and would not have required alteration. The cross section details and the overall length of the deviation however correlate well to the actual deviation on the Port Augusta side of the Saltia level crossing which I will describe shortly. An explanation for the apparent incorrect location for this deviation cannot be given.

Matching the proposed beginning and end of each deviation to the actual locations along the railway today has not been easy. Pichi Richi Railway's only document that records curve radii, tangent points, lengths of straight etc. is a copy of a Commonwealth Railways' re-railing diagram which dates from the late 1920s and distances are recorded from Quorn and not Port Augusta. It notes the dead end at Port Augusta is at the 259 mile 8 chain. The roll plan records locations from mileage 00 at Port Augusta, but where was mileage 00 at Port Augusta? Was it at the centreline of the old station building? (which still exists on Commercial Road as the Curdnatta Art Centre) or was it at the dead end recorded above remembering that the tracks continued on along Gibson Street and around onto the wharf area, or was it somewhere in between? This is for some further research to resolve on another day.

Anyway, moving to describing the locations of the other seven deviations it is probably best to start from the Port Augusta end of the Pass and work towards Quorn. In this issue the three deviations in the Saltia hills area will be dealt with.

The first is located between the 249¼ and 249½ mile posts and involves curves 80 and 81 and the straights uphill and downhill. Presumably curves as tight as 5 chains were eased to one of 8 chains and one of 9 chains respectively. Works were cleverly designed to enable the original 10 foot timber transom culvert midway around Curve 80 not to be relocated or extended, as the new and old curves were essentially coincident at that point. The current rail decked culvert is just off square to the abutments suggesting that the original curve crossed over the current alignment at that location.

A deeper two sided cutting replaces the original route at Curve 81 and the earthenware pipe culvert at the Quorn end of this curve has been extended uphill. The length of the straight between Curve 81 and Curve 82 has been shortened to accommodate the new curve. At the other end the straight between Curve 79 and 80 appears to have been realigned for its entire length to accommodate the position of the new Curve 80.

The next location is between 248 and 248¼ mile posts and involved the redesign of three curves, at least two of which were originally as tight as 5 chains radius. Today these curves are numbers 69, 70 and 71.

The embankment under Curve 69 was widened and the 10 foot concrete arch culvert was extended some distance towards the creek. The tangent point of the curve moved further towards Quorn and across the main road level crossing at Saltia, resulting in a slightly shorter straight on the main line at Saltia station. Curve 71 was repositioned towards the creek also, with the new alignment supported on a little seen dry stone wall. The original 2'6" wide timber transom culvert was bypassed and the drainage extended in the form of an earthenware pipe that discharged through the new stone wall. These works on Curve 69 and Curve 71 enabled Curve 70 in between, to be eased out to 7 chains on the ledge above the creek with minimal hard rock excavation. At one point, the new and old Curve 70 would have been coincident.

The third deviation was not much further along at the 247¾ mile post between Saltia and the Saltia bridge. Here, another tight radius curve approaching the Saltia bridge was eased out to 6¾ chain radius before the excavations into the towering rocky cliffs would have become too expensive to shift for little additional benefit. This curve is known as Curve 67 today and the original 5'-0" timber transom culvert was replaced with a 5'-0" concrete arch culvert. The original concrete headwalls can be easily seen from the train just on the roadside, midway around the curve. The alignment of the short straight between Curve 67 and Curve 68 has been cut further into the rock face to allow the easing of the curve, and possibly lengthened slightly. Curve 68 may also have been eased slightly, but the variation in position is only a metre or so at most.

In the final part of this story of the deviations in Pichi Richi Pass the remaining four will be described. One is located between the Big Dipper level crossing and the Lattice Bridge whilst the other three are located between Woolshed Flat and Summit.

Part 3

One of the benefits of placing historical research into the public domain, however complete it might be, is that it often results in valuable responses from others. Either new information becomes available to complete the missing pieces or controversy is resolved.

The story of the deviations is no exception. Long-time member, and current editorial team member John Evans came forward: to my delight with two original roll plans. One details Deviation No. 5 and the other deviations, numbers 4, 6, 7 and 8. These plans show the layouts of the deviations and clearly show the new and old curves, the changes to the curve radii and the precise locations of the start and finish of each.

Alas, the original plans of deviation numbers 1, 2 and 3 still elude us. However, armed with this new information I can provide some further details of Deviation number 5, described in Part 1, which could not be gleaned from field observations alone. I had suggested that Deviation number 5 extended to the Woolshed Flat end of Curve 41, where in fact it continued to include Curve 42 and Curve 43.

These curves were originally 6.5 chain and 6 chain respectively, and both were flattened to 7 chain. Curve 43 was moved towards the hill by only about 650mm, and Curve 42 was moved away from the hill by around 2.0 metres, placing it quite close to the edge of the bank above the creek bed. These adjustments would appear to have helped the positioning of the more significant relocation and orientation of Curve 41, from 6 chain to 7 chain.

Now to describe deviations 4, 6, 7 and 8. Number 4 is the only deviation between the “Big Dipper” main road level crossing and Woolshed Flat. Located around the 245¾ mile post it involves what we call curves 55 and 56 today. Heading down hill, Curve 55 was originally two left hand curves separated by a short straight of about 20 metres. The Quorn end curve was, and still is, 9 chain radius but the next curve, call it Curve 55A, was only 5 chains and avoided considerable earthworks as the railway rounded a rocky spur high above the road and creek. To flatten Curve 55A to 7 chains involved blending it directly to the 9 chain segment and digging a cutting through the spur.

To blend it back into the existing alignment after coming out of the cutting involved not only reducing the length of straight between Curve 55A and Curve 56 from around 80 metres back to 30 metres but also making Curve 56 sharper! Curve 56 was required to be reduced from 8 chains to 7 chain radius for about 80 metres at the Quorn end. The deviation therefore finished about 60 metres on the Quorn side of the 20 foot bridge.

The remaining three deviations are between Woolshed Flat and Summit. Deviation 5 has been described earlier, so we arrive at Deviation number 6 located generally between the 242 and 242¼ mile posts. This is the section that involves Curve 28, Curve 29 and the straight towards Curve 30.

Curve 28 was originally 6 chains in radius and was eased out to 10 chains, but the commencement of the deviation involved pushing the new tangent point uphill about 80 metres towards Curve 27 and Pichi Richi Straight. This work was necessary to deal with the real problem, Curve 29, over the well-known high, curved dry stone wall. Most who have worked on or walked along the track will have noticed that the alignment of this stone wall is sharper than the current track, so again the designers have made the old and new track coincident over the wall to prevent re-building. Curve 29 was successfully eased from 5.5 chains to 7.5 chains, but to do this a 50 metre long straight cutting had to be dug between Curve 29 and Curve 28. Also a very short 20 chain radius curve, call it Curve 29A disappeared altogether at the Woolshed Flat end as the new downhill end of Curve 29 picked up the straight from Curve 30 which was lengthened by about 90 metres.

The plans actually show 29A remaining and increasing to 30 chains but clearly this hasn't happened as there is no curve there now! Three concrete arch culverts were replaced by three rail decked culverts in this deviation; two are 2'6" spans and one 5'-0" span. All of the original structures can be easily seen from the train on the main road side.

Deviation number 7 involves the two curves behind French's Farm (the Brown's residence) near the 241 mile post. Again, going downhill the sweeping left hand Curve 24 started life at 6 chain radius. To ease this to 7 chains required Curve 25 at the Woolshed Flat end to be reworked also, and it was tightened up from 20 chains to 18 chains. The 5'-0" concrete arch culverts under Curve 24 required lengthening towards the creek by about 3 metres.

A note on the drawing states that a retaining wall is required to negate the need to purchase land at the Woolshed Flat end of the realigned Curve 24 as its new position placed it very close to the railway reserve boundary in a shallow cutting. This poor excuse for a dry stone retaining wall remains today with stones continually dislodging and falling into the trackside drainage ditch. This is quite unlike all the other magnificent examples of dry stone walling along the railway.

The final part of our story is deviation number 8 between French's Bridge, near the 240¾ mile post and the 240¼ mile post (between the Quorn end of Curve 19 and the Woolshed Flat end of Curve 22, when travelling downhill).

Again, starting at the Quorn end the deviation commenced by shifting the tangent point of Curve 19 uphill by about 20 metres. The curve remained at 10 chain radius but was lengthened somewhat to provide a better angle of approach for works further downhill. The 5 chain straight between Curve 19 and 20 was reduced to about 1.5 chains (30 metres) in length allowing Curve 20 to be eased from 6 chains to 7.5 chain radius and Curve 21, by means of a curved cutting, to be eased from 5.5 chains to 7.5 chains.

A 120 metre long straight was created between Curve 21 and Curve 22 to completely remove another curve (21A!) which was 8 chain in radius. Curve 22 was then eased from 5 chains to 8 chains, again by means of a curved cutting, this time primarily in soil rather than rock.

The old route that involved Curve 21A can be identified by two concrete abutment remains of the original timber transom culverts near the base of the highway embankment.

In concluding this description, it is worthy to report on various notes found on the plans.

1. Estimated cost of Deviation. The following faint pencilled costs were recorded against each deviation. It is estimated that the total cost of works of this nature today would be around £5 million ($10 million)
   • number 4            £550
   • number 5            £4404
   • number 6            £675
   • number 7            £528
   • number 8            £1627
2. Tracings were forwarded to the Resident Engineer on 26/7/1886 and 8/7/1887 and works were listed as completed by 1/5/1888
3. These drawings were cancelled and replaced by drawing numbers W40/15a, W40/16a, W40/16b and W40/16c (these were probably the actual "as-built" drawings, rather than the proposal) but have never been located.
4. For mileages on the plan, (ex-Port Augusta) add 6.08 chains to obtain actual mileages from centreline of the goods shed. Also note the passenger station is 31.03 chains forward of the goods shed at Port Augusta.

No wonder I had the troubles I mentioned in the earlier articles when trying to relate the locations to mileages on the re-railing diagrams which were recorded in miles from Adelaide via Quorn.

This article by Hayden Hart was published in Pichi Richi Patter Volume 40 No. 2 (Part 1), Vol. 40 No. 4 (Part 2), Vol. 41 No. 1 (Deviation No. 8 plan drawing) and Vol. 41 No. 2 (Part 3)