They are quicker because they are above the first couple of floors. The basement and the first few floors are not standard floors in terms of design. Hence the construction is more complex and takes longer as the forms have to accommodate the different design elements. Now that they are on higher floors, ones that are standard in design, the forms don't have to be changed. This allows them to rise faster. Same thing will take place at Bay Adelaide once it gets up a few floors.
Small Update from last Tuesday;
[A previous post mentioned that the forms were quicker on this building compared to at Bay Adelaide, They look the same.
I seriously don't understand why buildings take so long to be built nowadays. The Empire State Building was built in a year. How can a building of this size take two years or more?
Buildings in general were built much quicker in those days. Plus they didn't have the equipment we have today. I just think workers are lazy today and take way too much time to complete buildings. A glass tower should not take so long, there's no intricacy in the detailing.
We have the Ministry of Labour, strong unions and high safety standards here. Combine that with fewer people on a site means structures get built slower. Hundreds of cheaply paid immigrant laborers have died building Burj Dubai (for example). Thankfully that rarely happens here.
The time frames still don't make sense. Sometimes a 1000 footer can be completed in the same time as a building half it's size. How is it that cheaply paid, immigrants/labourers (that probably had no real training) built much more intricate buildings and at a faster pace than skilled workers of today with all our cranes and machinery?