Re: Insulated Rail Joints.

[signal_spotter@my-deja.com]

It sounds like traction tie-in bonds. On dead end sidings, Block Joints
are put into the rails for the track circuit extremity and the end bits
are then tied together for the return traction negative to the
substation. You may notice, around points, steel boxes (about 1m sq)
mounted on posts. These are Impedance Bonds and their purpose is to
allow the 1500v traction return current to flow around the Block Joint
but still provide electrical isolation for the track circuit.

regards Ian
Signal Design Engineer

In article <39B9CCB9.A65CE111@ozemail.com.au>,
  trainman@ozemail.com.au wrote:
> Tony Gatt wrote:
>
> > After an early morning trip to Campbelltown, and a little
inspection of
> > Platform 4, I noticed that Platform 4 now has track circuiting.
> >
> > I understand the reasoning for that, however...
> > What I don't understand, is that 5ft before the buffers, both rails
have
> > Insulated plates connecting the full length of track with the last
5 ft that
> > stop at the big concrete block at the Up end of platform 4.
> >
> > Why would the signal engineers go to the trouble of insulated
joints 5 ft
> > before the buffers, when the track is insulated by the sleepers and
a 4ft
> > 8.5 inch "air gap" at the end of the line.. weird..
>
> The only explanation I can think of, which probably doesn't apply in
this case,
> is that the buffers could be made of steel.
>
> --
> David Johnson
> trainman@ozemail.com.au
> http://www.ozemail.com.au/~trainman/
> ------------------------------------
> These comments are made in a private
> capacity and do not represent the
> official view of State Rail.
> C.O.W.S. Page 11.
>
>


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