Renew the rail network and save the planet

On or around Wed, 22 Jun 2005 08:07:59 +0100, Ian Rawlings enlightened us thusly:

In the old days, they spread tar on the road, applied a layer of small (about 10-12mm) chippings, and rolled them into the tar with a big roller. Now they spread tar emulsion, apply larger chippings and still roll it, the overall effect is utter crap. I reckon it's a combination of effects:

1) tar emulsion may not be as sticky as plain tar 2) tar emulsion makes a thinner layer on the road 3) larger chippings don't adhere so well in the thinner layer of tar 4) larger chippings create more leverage on the bond at the base when subjected to sideloads, such as created when cornering.

By contrast, the hot-rolled macadam system where small chippings are mixed with tar and then spread by the big spready-machine, and then rolled, while presumably more expensive, produces a superior road surface which lasts for ages.

I question how much more expensive it is, at that - consider:

1) the raw materials are much the same - chippings and tar 2) the raw materials have to be transported to the site 3) the roller is the same 4) the spreading machine is extra, but the tar spreading tanker is absent

I suppose somewhere there's a huge machine that makes the mixture in the first place, to put in the tippers that bring it to be spread. But overall, I doubt it costs as much as double, (or I doubt that it *should*) and it produces a road that lasts much longer.

Given the way the highway authorities treat green lanes -- use the cheapest resurfacing method possible that lasts less than a year despite the 15-year alternatives not costing 15 times as much -- I expect it's the intense short-termism to blame. What's the point in them spending our money wisely when they're not likely to be around to get the votes, err I mean thanks..

Ah but the first is really just a thin surface treatment on top of a worn surface layer and can be applied several times before the road needs to be planed and relaid. The second requires the old surface layer to be removed by surface planing for a couple of inches and then the new macadam laid. If you don't drains and man hole covers become hollows and kerb stones are half height.

On or around Wed, 22 Jun 2005 17:07:34 +0100 (BST), "Dave Liquorice" enlightened us thusly:

Point is though that the surface of the hot-rolled takes MUCH longer to wear.

good point, but then they use the resultant debris for filling hollows in verges and the like. It does add to the cost of doing it, I guess. But I bet it's still cheaper long-term and produces better results.

Peter schreef in berichtnieuws

42b1bc5a$1 snipped-for-privacy@mk-nntp-2.news.uk.tiscali.com...

Seen on the back of a truck:

Without trucks the roads would be empty - so would be your refridgerator.

nuff said.

I'm a railway signaller (signalman) so I agree!

Ron