Wouldn't using existing space next to the current rail alignment make more sense. It was originally quad track so there's space, and I don't know when you last when down Abbeydale road but it's not exactly got lots of space...
I thought that as well. There do appear to be a few places where the alignment has been narrowed though so there might be a need to run single track or even switch on to the heavy rail lines unless the obstructions can be removed.
As an aside, there is mention of a plan to extend to Chesterfield but not which way. To me it seems to make sense to do this as another train tram route. There are plenty of places new stops could be added (or old stations reinstated) such as Unstone, Whittington Moor and, if it ever happens, the new Peak development at Sheepbridge. I've thought for a long time that a park and ride just off Bowshaw roundabout would make a lot of sense as well, capture the traffic before it gets in to the denser road network of Sheffield.
The main issue is likely to be capacity (and future plans) of this route, and the ability to work trams in and around the heavy rail services. I recall that one issue with electrifying this route was with limited clearances at Dronfield - I wonder if there is scope for either a new alignment or to re-route all mainline trains a different way to resolve that issue, and as a happy aside to make it easier to make it tram-only?
I wonder also if there are plans to extend the network beyond the centre of Chesterfield - there are some big new developments on the way to Clay Cross for example.
I am actually surprised extension to Chesterfield is on the cards. There were plans for us to joint the Sheffield Mayoral authority but that got kyboshed by the council, despite there being popular local support for it, not to to mention very strong economic and social links between the two. We've now been put in to an East Midlands authority with no real say in the matter despite being an outlier in the area, so to even have the opportunity to still be better linked with Sheffield is great.