I'm trying to collapse all divided roads in one centreline and to integrate any other spurs or errors in the dataset to create one set of centrelines. I have used Merge Divided Roads but it leaves a lot to be desired (most of the roads I wanted collapsed did not merge).
Here is the dataset:

And here is what happens when it is collapsed:

I have also repaired geometry, reprojected and made it into a singlepart feature but nothing seems to work. I have tried it on multiple computers.