TRACK CONSTRUCTION

Posted on Jul 2, 2009 in Media Releases

Track Laying Sequence

Bottom ballast
Bottom Ballast is delivered to site from the stockpile location by road using a tipper truck. The tipper truck reverses onto a ballast box, which is adjusted to give a constant depth of ballast, the ballast is then tipped into the ballast box and the tipper truck drags the ballast box along the formation to deposit the ballast.

Installing concrete sleepers
The concrete sleepers are laid onto the bottom ballast by means of a road/rail excavator, with a sleeper grab attachment, the sleepers are either delivered to site by rail wagons or transferred from alongside the track onto the bottom ballast. The concrete sleepers are laid to the specified spacings.

Installing the long welded rail strings
The 216m long welded rail strings are loaded onto the bogie rail train at the Flash Butt welding plant, the long welded rail strings are then delivered to site. The rails are either winched off the bogie rail train directly onto the concrete sleepers or if the concrete sleepers re not installed winched off the boggier rail train directly onto the formation using rollers.

Fastening the rails to the concrete sleepers
The fastclip rail fasteners are delivered to site with the long welded rails. Once the rails are on the concrete sleepers, the rails are fastened down using machines.

Delivery of top ballast
Ballast is loaded into rail mounted ballast hoppers at the designated ballast stockpile locations and is then delivered to the site, the ballast is then dropped onto the track both in the centre and at either side.

Tamping
The track is then set to line and level with the Plasser tamping machines which also compacts the ballast under and around the concrete sleepers.

Ballast Regulator
The Ballast is then set to the required profile with the Ballast regulator machine.

Tunnel Track Work

The first tracks are currently being installed in the tunnel section of Gautrain between Marlboro and Sandton.

The track construction within the tunnels utilises a ‘state of the art’ trackform system, consisting of pre-cast concrete blocks, surrounded with a rubber boot cast into concrete.  This is different to the non tunnel sections which uses a conventional ballasted track system instead of concrete.

Tunnel track construction is currently advancing from Marlboro to Sandton.  The rails and pre-cast concrete blocks are stockpiled at the Flash Butt Welding facility at the Marlboro Portal.

Track Components

Running Rail: UIC60 E2 Rail Profile Grade 260 – Depot
UIC60 E2 Rail Profile Grade 350 Heat Treated – Mainline
Switches & Crossings: 1 in 9, Fixed Crossings – Depot
1 in 12,  Moveable Frog – Mainline Ballast
1 in 12, Moveable Frog – Mainline Ballastless
1 in 18.5, Moveable Frog – Mainline Ballast
Rail Fastener System: Pandrol Fastclip, with Cast-in shoulders, Rail Pad and
Side Post Insulators.
Concrete Sleepers: B70 with 1 in 20 Rail Inclination
B70 with Zero Rail Inclination
Booted Block System: Sonneville Booted twin Blocks for the Ballastless track in the tunnels.

Track Materials

  • UIC60E2 Running Rail – 1,030Tonnes of Grade 260 and 10,072Tonnes of Grade 350
  • 21no. 1 in 9 Depot Turnouts (1no. Temporary for Construction)
  • 2no. 1 in 9 Derailers in the Depot.
  • 9no. 1 in 12 Turnouts for the Mainline
  • 50,715no. B70 Inclined Concrete Sleepers
  • 1,650no. B70 Flat top Concrete Sleepers
  • 60,000 Sleeper sets of Pandrol Fastclips, Pads & Insulators
  • 47,806 Tonnes of Track Ballast
  • 3,376 Sonneville Blocks
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