Re: Why Wooden Sleepers are better. Was [NSW] CityRail Delays Friday

[davep <davep@quik.com>]

> > And concrete can be recycled.
 
> I think that is a bit short sighted. Concrete can be recycled but not
> very efficiently same with wood. I'm not really sure what recycling
> entails, I'm guessing that it's merely crushing up the concrete and
> using it as aggregate (like recycling high grade refractories into lower
> grade refractory bricks) rather than reforming.

	Wellll.
	One has to crush something to make concrete.  One can crush
	old ties (saving a bunch of digging of materials), and cutting
	trees, and disposing of old ties, or one can crush fresh materials.

	(and experiments are being done with recycling plastics into
	ties.  Drinks bottles, that sort of thing...)
 
> But as you did mention, trees take 100 years to grow whereas some of the
> ingredients in concrete may be virtually considered as unsustainable
> resources.

	If theya re made from crushed old concreet ties, sounds fairly
	sustaianable...

> Future planning can be done to ensure a sustainable supply of
> wood for railways, however I don't think you can do the same for sand
> and lime movements. Once it's taken, it's taken you can't replant sand
> or limestone for future collection.

	One can use old ties, instead of fresh sand...

	best
	dwp