According to the above link the walkway has to be removed from the old bridge before more lanes can be opened. Heaven knows why.
The guardrail for the new bridge occupies the same physical space as the old walkway, which was bolted on to the side of the old bridge. They couldn't remove the old walkway until the old bridge was closed and resurfaced for pedestrian/bike use. So, temporary barriers reducing the width of the new bridge until then.
As mentioned, all 6 lanes are open now, and now the old bridge has temporary barriers either side. This is because some sort of new barrier needs to be attached to the old bridge, because the old barrier is literally chicken wire tied to the trusses (which apparently was sufficient for the traffic only side)
Drove it yesterday in both directions and still 40 km/h signs up. We also have the roads surface completely stuffed in both directions as the bitumen is all in patches and not laid correctly very bumpy. I would argue it is far from finished but we have very low standards in Victoria.
They were preparing to lay a new quiet surface. It's really good!