Recently new Towers have been erected along the Main Western Line with the first or last, depending on your direction of travel, about 100 metres on the down side at the Bathurst end of the 'New Station' at Lithgow.
The next I saw was at Clarence and another near Bell.
I am guessing these Towers are to finally provide effective radio Communications between Lithgow and either Penrith at least or Sydney after the Coronial Inquest into the collision between a Double Deck Interurban and the Indian Pacific in the Glenbrook area found there were huge 'blackspots' in the coverage by the radios in use at that time.
Having worked Valley Heights as a Signalman back in the 80's, the coverage barely reached Blaxland to the East and Falconbridge to the West.
Even with a base attached to an external antenna, most signal boxs range rarely exceeded a maximum of 5 kms with dead spots within that distance.

Gordon,

Those towers are being extended throughout the Sydney Trains / NSW Trainlink electrified area. The towers form part of the DTRS (Digital Train Radio System) being rolled out as we speak. DTRS is built around the GSMR radio protocol using 1800MHz frequencies. It is a replacement service for the 400 MHz Metronet Train Radio System. The DTRS system's coverage of the rail corridor is quoted as 99 percent.

GSMR uses cellphone technology to provide that coverage. Towers are located closer to each other than with the Metronet system, this is to avoid any black or grey spots that may have been identified. In deep cuttings or tunnels leaky feeder is / will be employed.

When Valley Heights Signal Box was in operation the primary radio was WB, with a little bit of Metronet starting to appear. WB was a UHF single frequency simplex channel running at 5 watts for portables and 15 to 25 watts for signal box radios depending on their location. Both DTRS and Metronet employ multi site repeaters in order to reach the corridor.

R

Thanks for the reply railscan,
The H/Helds were Motorola single channel and the S/box radio was a Phillips 880 from memory running on 450.050 MHZ, at least for the west.
In the beginning North,South and West had different frequencies as we found out when they commenced an additional air conditioned car set called 'The Summit' running in conjuction with 'The Fish' and 'The Chips' to ease passenger loading.
The set came from Sydney as an empty car set and carried the radios from the previous run on the South which didnt help when I had a Signal Failure one morning and couldnt communicate with the Guard and Driver.
To the best of my knowledge there was never any 'repeater' or talk through facilities anywhere between Lithgow and Sydney and I worked at all the box's except Mt Victoria between Valley Heights and Bathurst West.

There was nothing wrong with the radios, it was purely the topography on the mountains that caused poor range and many 'Black spots'.