What is the train train proposal - just extending the Met from Altrincham?
Hale makes sense. Beyond that isn’t really dense enough to be so viable. Knutsford is underserved but I don’t think this is the solve. Plus the level crossing etc...
Does any freight pass through Navvy Road?
TfGM has not yet published any detail on the Hale tram-train "pathfinder" project. My guess is that the main objective is to validate track sharing on a busier line than that through Rotherham, particularly the feasibility of fitting a frequent tram-train service around long, slow freight trains as well as the hourly Northern service.
I imagine that one of the two Metrolink Altrincham services would be extended to Hale - most likely the Altrincham - Piccadilly, to minimise the number of vehicles needed for the pathfinder. That would give Hale a 5tph frequency. The Deansgate Junction track and signalling would probably be reconfigured so that the tram-trains could share the heavy rail single track section through Navigation Road, at least in the southbound direction. That would ease pressure on the parallel Metrolink single track section and improve resilience to disruption.
The Metrolink 750V DC OLE might be extended to Hale, or maybe the vehicles would be equipped with batteries for power on this short section.
There are up to two freight paths per hour per direction through Navigation Road, although many of them are not used. The most frequent flows are Greater Manchester binliners to and from the Runcorn energy from waste plant and, northbound only, biomass trains from Liverpool docks to Drax power station, plus Merseyside binliners from Knowsley to the Wilton energy from waste plant.
The freights take a long time to clear the Navigation Road single track section because of the 15/20mph restrictions around the sharp curve between Deansgate Junction and Skelton Junction. That could make it challenging to timetable the tram-trains around them without causing delays to other Metrolink services.