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  • SheffieldPark 28 May 2012 at 17:03
    Third Rail between Broad Gauge and Standard Gauge would be more practible if

    * electric operation of points and signals

    * four rail mixed gauge avoiding too close gap of 6.5inches between BG and SG rails.

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19 corrections, most recently by Corio - Show corrections



Engineer's Evidence.

Objections to any adoption of the third rail system, which he condemned as rela- tively dangerous on mixed gauges of 4ft. 8½in. and 5ft. 3in., were expressed by Mr. J.A. Smith, consulting engineer, who gave     evidence yesterday before the Federal     Public Works Committee at Federal Parl- iament House. The committee is in-

vestigating the proposal to extend the Great Western Railway from Port Augusta to Red Hill and to lay a third rail to   provide a track of 4ft. 8½in. or the South Australian 5ft. 3in., between Red Hill and Adelaide, is being made by the commit


In explaining the disadvantages of the   third rail system, Mr. Smith said that the   adjacent rails in a three-rail combination     of these gauges would be so near that the closeness of the flanges would militate against effective spiking of the sleepers, and the rails would constitute a channel that would unavoidably become choked     with sand, mud, ballast, and other debris, thus preventing, throughout its whole length, that continuous and close inspec-

tion that is the price of safety. Limited space would also decrease the effective- ness of the work of platelayers. Standard fishplates were designed to give added breadth to the flange of the rail, thus giv-

ing compensating lateral strength at a  

point otherwise weak, and because of such breadth to resist better the tendency of

the rail to turn under the outward thrust       if the wheel flanges. This limited space   between the rails required some reduction   of the lateral strength of standard fish-   plates

Reduced Strength.

Points and crossings were recognised

the places of danger, because a loose mem-       ber could never have the strength of a continuous, rigidly secured rail. The  

function of points was to deflect a train from one part into another, and, there- fore they must be capable of sustaining an impact, laterally, of up to 100 tons moving at a high rate of speed. Again, the limited space between the rails would unduly reduce the strength of the elements   compared with the practically unlimited space now available.

Mr. Mackay.—Have you any information   as to the use of the third rail in Aus- tralia at Wodonga, Tocumwal, Snowtown   (S.A.) and Port Augusta wharf ?

Witness.—Such cases are localised and

limited uses, under special supervision, of third rail methods for a traffic relatively   slow or slowed down to meet the disa- bility. These conditions do not apply in the case of high-speed, heavy express         working over 100 miles or more. This system was installed at Wodonga to over-  

come the difficulty of break of gauge over a short section. Its installation was due to a lack of foresight in the past in not unifying all Australian railway line gauges at the time of then construction.

In answer to the chairman, Mr. Smith said that be was not aware of any instance   outside Australia in which a third rail was     used to permit of rolling stock of 5ft. 3in. and 4ft. 8½in. traversing the same route.