You may not see it from space like the Great Wall of China, but the first of 350,000 limestone blocks were laid just north of the future Alkimos Station to build approximately 20km of retaining walls.
Made from limestone or recycled concrete, the retaining walls will provide a stable framework for the walls on either side of the rail line in the cutting below ground level.
Over in Butler construction of the road-over-rail bridges, which will enable safe crossing of the rail for people and fauna alike, has started.
Works including traffic diversions, service relocations, piling and excavation will start at bridge locations from Butler to Yanchep.
To minimise community impact, some of the bridges will be built using a 'top-down' method, including where existing roads will become road-over-rail bridges at Santorini Promenade (Butler), Pipidinny Road (Eglinton) and Yanchep Beach Road (Yanchep).
While the top-down method is not as commonly used as the traditional 'bottom-up' bridge building technique, it has advantages for road users and the community because it uses a smaller area.
As there is enough space to build temporary diversion roads alongside existing roads, traffic can be redirected during bridge construction to maintain connections. An example is at Santorini Promenade in Butler, where the diversion road is already carrying traffic while the new bridge is being built alongside it.
Check out the below graphic for a quick introduction on the 'top down' method.
