The two routes are Roseburn down to Granton, and down Newington Road to Cameron Toll and the Royal. For accounting purposes they are one route, for infrastructure purposes they are two completely separate routes. The southern route is much more costly simply because its down a very busy road, but that is where the confusion comes from.
With regards to the proposal...
Firstly, unless you propose to run the route as a disconnected entity, with captive rolling stock and a new depot, you're going to have to tie it into the existing route somewhere. That somewhere is going to have to be the western end of the city centre, otherwise you disconnect the sub from the depot whenever Princes Street is closed. Furthermore, you have to send trams from the sub into the city centre, which means somehow connecting them into the existing tram lines somewhere near Murrayfield, and sending them eastward, otherwise this line isn't ever going to break even. There isn't enough demand for an orbital tram route that doesn't go anywhere near the city centre, and if there isn't enough demand, then why would the council ever agree to fund it?
Indeed, they do propose to join the existing route westwards to Balgreen, crossing the E&G on a flyover. That's two junctions tying into the existing tram line and the sub. The southern end tying into the sub: you'd have to buy and demolish some of the Varamova Pharma factory, but ultimately not a deal breaker. The northern end, tying into the existing tram line: you'd have to buy some of the Murrayfield pitches, and then have a junction elevated above ground level to a significant degree, either above the Water of Leith or inside the back gardens on Baird Drive. Again, not a deal breaker, but this cost is going up and up and up.
They also propose running another new line from the sub (this is looking more and more like you're going to have to demolish the entire Varamova factory, which means more money) under the E&G (the bridge is already there so this is easy) somehow raise it up in an incredibly constrained site to join the existing line before it reaches Murrayfield Station. That's the main emergency vehicle access to Murrayfield Stadium that you're messing with, or you're buying part of Haymarket depot, which is too small already, and ScotRail would tell you where to get off.
At the eastern end, they propose a two level station for trams and trains, with a low part of the platform and high part of the platform. That makes sense. What doesn't make sense is the idea that you're going to use this project to remodel the entirety of the Niddrie Junctions, and Portobello Junction by extension. To get two platforms, presumably one in each direction, you'd need to rebuild the entire section between Portobello Junction and Newcraighall station, and any tram line heading north, and coming off after Brunstane station, which they propose, would mess around with signal overlaps to an extreme degree.
Then, after crossing on the Harry Lauder Rd bridge, you're building a mobility hub on the outskirts of Portobello that doesn't have direct trams to the city centre on an industrial estate bounded on one side by a main road and on the other by the ECML. its not an easy place to get to unless you're building a better access route than the very narrow Hope Ln footbridge, which will be necessary.
And finally, you're presumably going to have to redouble the Seafield branch, except the two bridges at Portobello Road and Fishwives Causeway, both of which were rebuilt at some point and only build wide enough for single track. Between Craigentinny and Salamander Pl, there's nothing worth serving unless you want to build a tram stop to serve a Halfords or a sewage farm?
All in all, this project can be summed up in two sentences.
If this project was in any way technically feasible, or economically lucrative, or socially beneficial, and the council knew about it, I'm sure that they would have jumped on the bandwagon; surely it would be in the council long term plan, or there would have been favourable words, or a feasibility study saying that it was a good idea. On the contrary, the opposite is true. There have been many proposals and petitions asking for this project, in every possible manifestation since the line closed, and never once has the council decided to go along with it.
www.bbc.co.uk
