While reading through historical annual reports for the Kowloon Canton Railway, I came across an interesting piece on the troubles they encountered sourcing suitable timber railway sleepers that could withstand Hong Kong’s tropical conditions.
The 1948-49 Kowloon Canton Railway annual report, page 16 is where I first read of their timber sourcing issues:
New Sleepers
During the year, the following quantities of hardwood sleepers were purchased:-
2,369 Siamese Hardwood Sleepers
301 Siamese Hardwood Crossing Timbers
4,000 Borneo Hardwood SleepersA local trading company failed to carry out the contract for the supply of 1,000 bridge and crossing timbers owing to the sudden imposition of a 10% export tax by the Siamese Government.
As well as the various types of timber previously used.
Kempas Sleepers. The majority of the timber sleepers removed from the track after the war (i.e. 1946 to 1948) were Singapore Kempas sleepers obtained as an experiment in 1938. These sleepers were creosote-treated. They started to rot from the core, and this was not easily detected from the outside until they were in an advanced state of decay.
Australian Sleepers. With the exception of the 2,000 pieces put in the track during Autumn 1946, all Australian hard- wood sleepers found in this Railway are over 15 years old and are still serviceable. No hardwood sleepers in these latitudes so far handled can compare with Australian Eucalypts.
Siamese Sleepers. Some Siamese sleepers were purchased six months ago, but it is yet too early to comment as to the probability of their useful life.
Borneo sleepers were received in the Colony in January 1949, and were first put in the track in April. Here again, it is too early to comment.
We are indebted to the Forestry Officer for the advice and assistance afforded to the Department on sample timbers, and the inspection of sleepers imported for Railway use.
As well as the experimental concrete railway sleepers that were developed in the 1920s.
Up to 31 March 1949 there were:
19,935 concrete sleepers on the Main Line
8,565 concrete sleepers on sidings
3 ,785 concrete sleepers lying in yard (not on track)32,285 concrete sleepers against an approximate total of 35,000 manufactured between 1920 and 1934.
It is worthy of note that after an average period of 22 years, 90% of Baker’s concrete sleepers are still in existence. Unfortunately it was necessary, however, when replacing 85-lb. rails with 95-lb., to remove the concrete sleepers from the curves in the Main Line due to the wider bottom of the new rail and the insufficient spread allowed by the concrete sleepers. The concrete sleepers thus removed were re-used in other places.
Issues sourcing timber sleepers continued through 1949-50.
A local contractor failed to fulfil the contract for the supply of 12,100 hardwood sleepers. Only 1,479 were delivered.
The successive non-fulfilment of contract for the supply of hardwood sleepers by local contractors in 1948/49 and 1949/50 has resulted in a shortage of 11,621 sleepers which means a delay in the renewal of 4 miles of tracks and 35 sets of points and crossings.
By 1950-51 the supply issues now related to the cresote used to protect timber sleepers from rotting.
In all, 22,727 Mai Yang sleepers and 3,322 bridge and crossing timbers were purchased from the Forest Industry Organization, Bangkok, through the Siam Rice Agency Ltd., acting as shipping agents.
The Forestry Officer, Hong Kong, recommended that the Mai Yang sleepers should be treated with 50% creosote and 50% diesel oil mixture by the open tank process, and therefore a pre-war plant for treating Kempas sleepers was reconditioned and used for this purpose. Work was started on 3.10.1950.
Owing to the intermittent short-supply of creosote from the United Kingdom due to shortage of drums, only 2,874 sleepers were treated in the first six months. An arrangement with a local firm of repute would have resulted in a regular supply admittedly at higher cost, but the Chairman of the Tender Board advised purchase through the Crown Agents. The final cost of the cheaper creosote will, in due course, be reflected in the earlier replacement of non-creosoted sleepers which are very difficult to obtain.
Some 1,121 very rotten timber sleepers lying alongside the track in the New Territories were sold as they lay: 5,500 were given to the Social Welfare Office for the use of a refugee camp, and 1,521 were brought back to Kowloon and sold to railway staff as firewood.
A shortage of hardwood sleepers delayed the main line re-railing program in 1951-52, with the work not completed until February 1953.
From that point it is believed that spot replacement of timber sleepers continued until the modernisation of the Kowloon Canton Railway through the 1970s, when the line was relaid in even heavier rail – UIC54 profile at 54 kg/m, or 109-lb. in the old measures – laid on modern precast concrete sleepers.
Footnote: the modern era
Timber railway sleepers are still used on the MTR system today, but predominately beneath points and crossings, thanks to the flexibility they provide for these pieces of complicated trackwork.
But timber sleepers can also be occasionally be found on tracks elsewhere – presumably due to clearance issues.
But since 2008 the MTR have made moves to replace them with “synthetic sleepers”.
There were originally about 10 000 “timber sleepers” on the East Rail Line (EAL). They are also used on relatively longer sections of Tung Chung Line and Airport Express Line.
Due to the ageing of and difficulties in procuring “timber sleepers”, the MTRCL has gradually replaced “timber sleepers” with sleepers made of synthetic materials since 2008 and will replace sleepers in the light of their actual conditions and ages. In terms of railway applications, there is no difference between the mechanical properties of synthetic sleepers and timber sleepers. The mechanical properties of both sleepers are in compliance with the Japanese Industrial Standard (Standard JIS E 1203:2007).
Generally speaking, “synthetic sleepers” have a longer lifecycle than “timber sleepers” and are able to improve the overall track reliability. Thus, “synthetic sleepers” are widely used in railway systems around the world.
The MTRCL started to implement the plan for replacing worn out “timber sleepers” on EAL in 2010. As at August 2019, 4,000 timber sleepers have been replaced by synthetic sleepers.
Since then the MTRCL has replaced over 2,600 “timber sleepers” to give extra track reliability. The remaining “timber sleepers” with better conditions will also be replaced by the end of 2021. By then, the replacement of all “timber sleepers” on EAL will be completed.
The “synthetic” sleepers in question are FFU synthetic wood sleepers manufactured by the Japanese company Sekisui Railway Technology.
Sekisui Railway Technology photo
The technology having been proven in Japan for decades.
FFU is produced by compressing single strands of glass fibre with polyurethane foam using a high-pressure extraction press. The manufacturing process is initiated by mixing the base materials polyole and isocyanide with several additives, and after compounding and extrusion, the raw mixture is reinforced with long glass fibres. Foaming and curing then takes place before the finished product is cut to a standard length of 12m for further processing and sizing to any length determined by customers.
One of the major benefits of the sleepers is their longevity. This was recently demonstrated in a study conducted by Japan’s Railway Technical Research Institute (RTRI) on behalf of Sekisui of FFU synthetic short sleepers and FFU synthetic bridge sleepers which have been in service in Japan for the last 30 years.
The survey results show that after 15, 20, 25, and 30 years in service the short sleepers exhibited no cracks and warping, no changes in the colour of the surface layer, and no loose screw spikes, and overall were in good fixed condition. Furthermore, the sleeper plates were in good fastened condition, while no peeling or cracks, or loose sleepers were found during observations of the bonded portions from the ditch side.
But were to blame in a September 2019 derailment on the MTR East Rail line at Hung Hom.
Thanks to the synthetic sleepers behaving differently under load than timber sleepers.
The Panel concluded that the derailment was caused by the dynamic track gauge widening beyond a critical level at turnout P5116. The investigation found that, in the early hours of 4 August 2019, the EAL Track Maintenance Team replaced two worn out timber sleepers with new synthetic sleepers to correct the track gauge.
Due to the special combination of rail alignment at a sharp curve, high traffic intensity and the difference in stiffness between the new synthetic sleepers and neighbouring sleepers in this particular location, this arrangement had an unintended consequence in that the two synthetic sleepers created a localised hard spot in the rail support system. This hard spot resulted in most of the sideways loading from the trains passing through this curved section being exerted onto the rail fastening of the two newly replaced synthetic sleepers, which accelerated the fastening’s deterioration.
Three of the fixing screws failed as a result, which allowed one of the rails to move sideways, leading to an increase in the gap between the two rails or “dynamic track gauge widening beyond a critical level” and train wheels hitting the check rail. This in turn led to the derailment.
So it seems nothing is ever that simple.
