Through weeks eleven and twelve of the project, more of the visible progress on the reconstruction became evident.
As seen in the photograph to the right, more of the original structural blocks were set in place (note the orange paint that designates that particular blocks original position). These large granite blocks that run crossways to the bridge are laid in place to help keep the bridge and subsequent roadway from shifting.
The size and weight of these large granite blocks are also essential to keeping the overall structure of the arch intact. The premise of a stone arch structures strength hinges on the weight an pressure from what is constructed above the arch. The massive weight keeps the voussoir stones bound in place.
Check out the Week 11 & 12 Time-Lapse
and walk through YouTube videos below to see the work in progress!
During the rebuild process, the teams are working both ends of the stone arch at concurrently. This is critical to maintaining a constant, balanced pressure on the arch. Too much added weight or pressure on one end or the other can cause a collapse of the arch structure.
As seen in the photographs to the left and below there is a constant shifting of construction between the larger stones, that require hydraulic assistance to place, and the smaller stones to ensure that the completed sections are solidly in place and are load-bearing for the next tier of stones.
You will see various and sundry hand tools laying around the team as they work. At times the stones will need to be "dressed", or shaped to fit in a specific spot.
In the photographs below, you will see some of what would have been the original curbing stones being set into their original positions. To increase the strength of the finished bridge and to help increase the longevity of the overall structure, the team will be adding newer (yet historically accurate) granite blocks above the original curbing.