HISTORY OF CIVIL ENGINEERING IN NEW SOUTH WALES. G05 



twenty inches apart from centre to centre. There are two 

 longitudinal beams which act as guard rails fixed on the top of 

 the cross beams ; these serve to distribute the concentrated weight 

 of the driving wheels of the engine over two or more cross-sleeper 

 beams. The testing of this bridge showed that the lateral bracing 

 of the main girders in a vertical plain caused the outer girders to 

 deflect more tlian the inner girders, which would not have occured 

 if the two main girders under each line of way had been braced 

 independently. The deflections of the main girders when tested 

 with engines which produced a load equivalent to 1 -4 ton per foot, 

 run on each line of way, was from three-eighths to five-eighths of 

 an inch. The links which form the bottom flange have an eye 

 at each end and one in the centre, which may cause the tensile 

 stresses in the links to be unequally distributed when the bridge 

 is traversed by engines having unequal loads on the wheels. 



From Parramatta Junction to Albury the first important work 

 met with is the bridge over the River Nepean ,at Menangle, about 

 forty miles from Sydney, which is designed to carry a double line 

 of railway. It consists of two main box-girders, continuous over 

 three openings, having each a clear span of one hundred and 

 fifty feet. The main girders are twenty-five feet six inches apart 

 in the clear, each forming a continuous girder four hundred and 

 eighty-six feet long, extending over two intermediate piers. 

 Between these girders transverse or roadway girders are placed 

 at a distance of three feet from centre to centre. The piers are 

 built of masonry spaced one hundred and sixty-two feet from 

 centre to centre, over three of which expansion rollers are placed. 

 The height of the bridge from the level of the water in the river 

 to underside of the girders is sixty-five feet. The approach on 

 the Sydney or northern side is nine hundred and seventy-eiglit 

 feet long in spans of twenty-six feet each of timber, constructed 

 for a single line. The approach on the southern side is of timber 

 four hundred and thirty-two feet in length in spans of twenty-six 

 feet. This bridge was completed in 1863. With a load of 1-4 

 ton per foot run on each line of way the maximum stress developed 

 in the top boom of the box girders is 4-32 tons per square inch, 

 and in the bottom boom 5*3 tons per square inch. The maximum 

 live load only slightly exceeds the deadweight of the structure. 

 With one ton per foot run on one of the main girders the greatest 

 deflection observed was half an inch. The Menantde Bridge was 

 the first large railway bridge erected in New South Wales. Since 

 its erection in 1863 the design has only been reproduced in the 

 Penrith Bridge. 



The viaduct at Picton over the Stonequarry Creek, fifty-three 

 miles from Sydney, is built of masonry, and consists of five 

 openings, of forty feet each. The arches are semi-circular, and 

 on an incline of one in forty, and in consequence of the proximity 

 to the Picton Station, it has been built for a double line of way. 



