Difficult to tell from a car stopped at traffic lights...but I'm guessing they'll have laid one track and left space for the other so as not to cause any further disruption to the railway...I'll be taking a trip from Kirkby to Rainford and back later today so will add an update. The bridge deck is metal. It was green, but I think they've since painted it black.
Does the bridge now actually carry a double track formation or has the previous single track been reinstated over the new bridge purely in anticipation of further redoubling works associated with the station construction? Also is the new span a concrete or a metal bridge deck?
The new bridge only carries a single track at the moment...but it is in its final position on the left hand side of the bridge if you were looking towards Kirkby station. There is a gap where the 2nd track will fit...so I doubt they'll need to close the railway again. (Trains don't run on this line on Sundays, so it'll more than likely be laid then.) The embankment has been widened fully now, so I doubt it'll be long before the 2nd track is laid.
The brick walls for the platforms are taking shape. The 2nd Liverpool bound platform (opposite where the station building will be) looks pretty much done, the longer Liverpool & Wigan bound platform (the side the station building will be on) needs a bit more work.