On 14/05/17 20:17, Mal Rowemal.rowe@... [TramsDownUnder] wrote:
>

> It's my understanding that the rails sit in an insulating 'boot' which

> sits in a slot in the concrete.

> The system is described at:

> http://cdm.eu/data_sheets/track/SDS-CDM-QT-EN%20(120906).pdf

>

> So the insulation should be OK.


Here's a shot of rails at Kensington with the 'rubber' attached ready
for installation. I've also observed workers cleaning the rail before
fitting the 'boot'.

It doesn't go to the ends to prevent damage when they weld the sections
together. After welding the 'infill' is applied 'in the field'.

>

> My concern would be if the concrete is strong enough - over many years

> - to hold the rails to gauge.


The original SLR track in Haymarket and Hay Street doesn't appear to
have suffered from loss of gauge over the last 20 years. The welds have
'dished' leading to a 'clunk clunk' as the trams trundle down the
street, but it would appear the gauge has stayed correct.
The SLR track had the rails dropped into pre-cast slots and then was
'potted' into position.

>

> Secondary concern (which I won't live to see ... and neither will the

> consultants!!) is whether, when rail replacement eventually becomes

> necessary, the rail will simply be able to be slotted into the

> existing channels in the concrete.

The 'system' designers claim the rails can be removed by making two saw
cuts along side the rails and then pulling them out. Presumably the
replacement rails would have to be reinstalled like the SLR track was
originally build - with the rails held in jigs and the filler poured in
around them and then left to set.

There are short sections down George Street where the rail slots have
been pre-cast into the concrete roofs of chambers under the track. (I
assume these will be APS equipment rooms - about 2 of them per block). I
assume they will not use pre-installed insulator across these but hold
the rails in gauge with the CDM jigs and pour in the filler and wait for
it to harden - the way the Hay Street track was originally constructed.