The distance from the centre line of track to the contact wire.

Is the contact wire offset from the centre line of the track.

The TW is supported by a cross span between poles and/or wall brackets.

The traditional suspension system used to provide supports for TW. The disadvantages are; Producing hard spots on the wire. (Not able to support higher radial load.)

Hanger & Ear, Frog, Crossing pan, D-Tensioner (Snow-shoe)

To provide service to pantograph only.

To provide services to both tram-pole and pantograph.

There are two types of operation used in Melbourne;

Like Tram-Pole, it also collects electric current from the contact or trolley wires. (YT: 3.67-5.97) _ (HR: 4.42-6.1_6.6)

It collects electric current from the contact or trolley wires via trolley shoe.

Trolley wire is used as an overhead power source for electric vehicle. TW or catenary wire comes in different sizes: 181, 161, 129, 107 and 81 mm2 .

The overhead system has suspended wires (OHW) above the length of the track. The power will be collected by the pantograph on top of the vehicle, which make contact with the Trolley Wire.

The first electric tram route constructed from Doncaster to Box Hill on Tram Road in 1889. Due to lack of knowledge and management and few problems with land owners the line died in 1896. Later on in 1906 the first electric tram line built servicing Essendon area and followed by St Kilda – Brighton line. The early trams were collecting the power by the tram-pole and later on the pantograph system introduced to avoid de-wiring caused by tram-poles. Today, Melbourne is the only city in the world which still serve two types of operations Dual and Panto. Nowadays, the tram-pole are only used in historical events.