Here is another shot from yesterday that shows the rubber boot being applied to the near track and already in place on the far track with the orange clamp piece holding the boot and also determining the gauge. It appears from the photo that there seems to be a screw adjuster within the orange bar for fine adjustment of the gauge. The gauge bars also have threaded legs for adjustment of the rail height above the track bed.
The track laying in the present work differs in a number of respects from the Jetty Rd works in May and June this year. At Jetty Rd the gauge was set by tie rods which were insulated from the reo-mesh between the rails and the rail height was set by stacks of concrete paver blocks and plastic packing pieces. The present method seems less labour intensive and enabled the track to be set in concrete in a couple of days.
Alex C - in the A City
---InTramsDownUnder@..., <rubberman92@...> wrote :
Fear not. Those little orange squares bolt onto each side of the orange bar and the foot of the rail.
Mark, not wanting Adelaide to be confused with Sydney contemporary track construction methods.
Sent on the go with Vodafone
-------- Original message --------
From: "Mal Rowe mal.rowe@... [TramsDownUnder]" TramsDownUnder@...>
Date: 8/10/2017 3:46 PM (GMT+09:30)
To:TramsDownUnder@...
Subject: Re: [TramsDownUnder] Adelaide Track Laying
On 7/10/2017 7:15 PM, Robbie Smith zoqaeski@... mailto:zoqaeski@... [TramsDownUnder] wrote:
The contemporary Melbourne approach of sleepers in concrete covered by a layer of asphalt is better wearing and simpler to renew when maintenance is required. It's also quieter as the materials absorb noise better than solid concrete.
Hi Robbie,
One key difference between Melbourne and the new systems in Sydney and Gold Coast is the design decision in the new systems to try to electrically isolate the rails from ground, The rubber boot serves that purpose as well as providing the same sort of resilient rail that the current Melbourne crushed rock and bitumen finish does. Melbourne used this sort of boot for a few years to reduce 'curve screech' before adopting the current construction method.
The Sydney / Gold Coast / Adelaid(?) technique means that tie rods and anything else connected to the rails also has to be insulated - or eliminated.
It looks to me like both the Sydney and Adelaide systems have chosen to eliminate tie rods and rely on the concrete alone to hold the rails to gauge.
In Sydney, it looks to me like there is a rectangular channel cast in the concrete and the rail in a very substantial insulating / packing 'boot' is lowered into that channel. Presumably when rail replacement is needed the whole lot - rail plus boot is removed and replaced.
The Adelaide pics puzzle me - it looks like the thin boot is just having concrete poured around it, including filling the gal between the foot and the head of the rail.
See: http://tdu.to/a56492 http://tdu.to/a56492
When rail replacement is needed, the concrete around the rail will have to be broken up - and I'm not sure how the new rail will be set to gauge. Perhaps they will just dig up the lot and repeat the current process.
Mal Rowe - sceptical about the long term viability of mass concrete to hold rail to gauge.