Metro

RE Crossrail Phase 1
That diagram recently shared is only one of several early design options investigated. The final design still not nailed down, But to be aware junction with bay line will be at-grade, mixing with traffic will be avoided (so no in-road sections, just road crossings), alignment/platforms at Central will accommodate connection west to the throat at the end of platform 8, likely no station in Callaghan Sq (given proximity of stations at Butetown and Central). Local highways have to be re-designed to wrap around...

Ah, this makes a lot more sense. So no need for the underpass then - both tram lines will rise to the bay line embankment and one will cross the other at grade?

looking at the diagram, the underpass didn't seem straightforward due to the high skew needed and that it sat between two existing bridges and there isn't much clearance so jacking a box section through the embankment might not have been feasible.

I think 'at-grade' means grade of Callaghan Square - not grade of bay line track.

But I dont think jacking an underpass through the embankment is feasible as there is not enough clearance and too much risk of settlement. So I predict that Bay line will have to close for a very fast and intensive operation - excavate section - install precast box sections - reinstate - could be done within two weeks with proper planning and preparation.

(Speaking as a Construction Manager who has executed similar fast track shutdowns before). Just keep Network Rail as far away as possible.

It will almost certainly all be at-grade...no need for underpass. Junction operating to tramway stds can clear LRVs much more quickly that HR....so at grade junction capacity more than enough to handle potential future services inc those from west when full connection to Cardiff west throat delivered.

Ok - I get the 'at grade' junction now. But I think it is a missed opportunity not to have a stop at Callaghan Square. Central Sation to Callaghan Square to Butetown is 400m between stations which is supposedley the optimum for tram stops (as opposed to rail).