Project Updates

River Slaney Bridge – N80 Structure 1

The new river Slaney Bridge is the longest bridge of our project (~154m) and one of the most challenging parts for our Joint Venture. Extensive design, construction methodology and procurement of all the structural components was required, as well as a big effort from our teams here on site in order to bring to reality  all these ideas.

The new Bridge is crossing over both River Slaney and the existing railway on the east side of the river and is a three span bridge. The two abutments are built as reinforced earth walls, and the two intermediate piers consist of 8 columns with a height of approximately 6m.

 

 

 

 

 

 

 

 

 

 

 

In the cross section above you can also see that foundation piles were required with depths up to 15m at the intermediate piers and abutments in order to increase the stability of the structure, which is being built on the banks  of the river that are also prone to flooding.

 

 

 

 

 

For the same reason, the area behind the West Abutment required the installation of 10 arch culverts which allows for flood water to flow through the plain and not affect the structural integrity of the bridge and the road above.

Back to our main structure; 12 steel beams in total were erected in place, 4 beams for each of the 3 spans of the structure. Each beam consists of a pair of steel girders which are connected together laterally with cross  bracings, and with bolts longitudinally in order to increase the stiffness of the deck (as shown below).

 

 

 

 

 

 

 

 

 

 

For the installation of the beams a crawler crane with a capacity of 360tn was required. During each lift and while the beams are still suspended by the crane, workers with harnesses had to do all the bolted connections. After this operation was completed the crane would release carefully the beams which now form a single truss structure resting on specially designed bearings at the two abutments and the two intermediate piers.

On the top of these beams permanent prefabricated formwork will be placed and reinforced concrete will be poured which will form a composite structure (of steel and concrete). A final surface for the pavement will be placed after that in order to allow for the traffic to travel over the river and railway line.

 

 

Below is a summary of expected works over the coming months:

Q2 2018
  • Well Monitoring/ Noise and Vibration Monitoring
  • Minor Remaining Earthworks
  • Drainage
  • Minor Structures Works – Repairs and Snagging
  • Side Road Works
  • Pavement Works
  • Junction Works

 

Q3 2018
  • Well Monitoring/Noise and Vibration Monitoring
  • Minor Remaining Earthworks
  • Drainage
  • Minor Structures Works – Repairs and Snagging
  • Side Road Works
  • Pavement Works
  • Junction Works

 

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