THE SYDNEY TRAMWAYS.

Press, Volume LXI, Issue 11955, 6 August 1904, Page 2

THE SYDNEY TRAMWAYS.

INTERVIEW WTTH MR J. C. MADDISON.

A GREAT BRIDGE.

Mr J. C. Maddison, architect, of this city, returned yesterday from a trip to Melbourne and Sydney. Mr Maddison, when seen by a representative of tto 'The Tress," said that business matters in Australia were by no means brisk.

While in Sydney Mr Maddison made himself acquainted' with the tramway ayetem there, which ie probably >the most advanced system of electric trams in Australia. The electric overhead wire system was introduwd for the first time on September 30th, 1893, in the shape of/in extension of the Xorth -Sydney wrvice from Falcon street to Spit road, a. distance of 2| miles. The ival commencement of the j.rcwnt eleetric era, however, came in 1899, with the opening of the line from Circular Quay to Pyrmont, a distance of 3 miles 19 chains, that introduced electric traction into the very heart of the city. The general nature of the olectrio system decided on vras the direct current 500 and 600 volt system, with overhead trolley wiring, the energy being principally generated at a central power-house by dynamos directly couplet! to compound condensing engines, and distributed by a. system of overhead and underground feeder-cables, controlled at the power-house by switchboa.rd fittings, and attached to the trolley wires at various points along the route of the trams, the energy being conveyed to the cars by the trolley wiring, and the electric circuit being completed by the bonding of the rails. This original scheme has since been supplemented by the installation of an alternating plant. Owing to the heavy grades and curves, the consumption of energy per car is high, averaging on the so-called city and suburban 6ection from 12J to 15 kilowatt?, which is much greater than it would be in a district of easy grades and straight runs like those of Christchurch.

The power house stands in a part of the city known ns Ultimo, so near one of the arms of Tort Jackson that supplies of water for condensing purposes are easily obtainable. The length of the building is 318ft, the breadth 186ft, and the ground floor area 59,148 square feet. It is a brick structure of throe storeys, on stone foundations, and has three brick chimneys of a height of 227ft and an internal diameter of 11 feet. The engine room has a length of 275ft, a breadth of 99ft, and a height of 30ft.' The prefent output of the station is about 90,000 kilowatt hours per day. Tho greatest distance which power has to he transmitted in any direction is nine miles. There are at present four sub-etations in active work, and a fifth sub-section is being equipped, and the batteries there are used for two hours in tho evening to help deal with the heavy loading at the end of the working period of the day. The rolling stock is of a variety of patterns, but all the cars are of one deck only. Tho lighting of the cars is by incandescent lamps. The average speed is eight miles per hour in the citv and ten .in tho suburbs. There are fixed stopping places, and the tmma do not. stop between these. The linea are divided into penny sections of an average length of two miles (in the city). The longest through run is Hi miles, the faro for which is 6(1. Tho staff employed numbers 4000.

Mr Maddison speaka enthusiastically of the Pyrmont wing bridge, which connects Sydney with Pynnont and the furrounding districts. The most part of thia structure is tho steel ewing span, consisting of ihe swing span, pivot pifr, raised tiers, and protecting platforms. Here the most intricate work was required, tho sinking of the caisson being a feat of engineering skill. The huge chamber of 42ft diameter had to be gradually worked down to a depth of 46ft below low water mark, and after the necessary damming it was pumped out. Excavation was then carried on in the "dry" until a "blow" occurred, wlwm the tedious process of excavation with water in the chnmber had to be resorted to. Ultimately tho work was satisfactorily completed, and filling operations have made the caisson a solid block of concrete and stone. The total length of the bridge is 1200ft, and the steel swing span is 223ft, while tho entire length of the work from tho Sydney approach to the end of the Pyrmont approach is 1758 feet. The shipping intera<rts have boon studied by the providing of two 70ft fairways and a 26ft headway above high water mark under the fixed spans, while a roadway with quickly opening and closing spans is provided for tho benefit of vehicular and pedestrian traffic. The operating machinery for turning* the span, etc., consists of etectric motors. The span can be opened in thirty seconds, but the average time is fifty «;conds. The electrical equipment of this bridge is tho most up-to-date, and the swinging spun is the quickest of operation in the world. The average cost of opening the swing span is Id per opening.