Light infrastructure makes progress.
Essentially, the tunnel is ready.

Left-to-right Tube tunnel, light rail tunnel, concrete mainline tunnel.
I have noticed one thing about tunnel portals in general.
Unlike the underground inage of tunnels, portal images don't seem to support seperating waytypes from the tunnel type visually.
It's all prepared in my gimp file to remove the tracks from tunnel portals image, but the game engine doesn't seem to support this, so I have just added the "cssr-light" track to the image.
Note, that in the following I will only use (maximum) width x height, instead of exact loading gauges for simplicity reasons and apart from "whatdotheyknow.com" question and answering it seems to be impossible to get such data.
e.g.
sub-surface class S7,
1972 stockA very interesting thing I have noticed about loading gauge is the loading gauge of Londons sub surface lines.
Most common loading gauge of modern mainline trains seems to be something between 2.70 x 3.80 to 2.80m x 3.95m
Most classes on Londons sub-surface lines have a loading gauge of 2.82x3.70 to 2.95x3.70
Note that's more in width but less in height compared to main line rolling stock.
That data given, I guess it's best to not let sub-surface stock use the "light loading gauge".
A width of 2.65m seems to be quite common to most (or all) of Britains light rail vehicles, including DLR, Tyne & Wear, Sheffield supertram and Croydon tramlink.
The height, differs from 3.45m of Tyne & Wear to 3.51 of DLR, further to ~3.60 of most modern trams.
However, it was quite difficult to get reliable data. Even data
created by Bombardier, officially provided by TfGM via whatdotheyknow.com seems to be quite contradictory. Compare the the technical drawing with the datasheet. They simply don't match at all. Height is different, width is different, Length is different, floor heighth is different, even the number of doors is different!
This one from Bombardier for Croydon tramlink seems more trustworthy.
I'd specify the virtual "light loading gauge" to roghly 2.65m x 3.60m, excluding pantograph.
That loading gauge seems to include all modern LRV, or at least most of them.
I am not yet sure if blackpools match that loading gauge. Their sepcified data seems to be wheel-to-roof, excluding the pantograph tower which, obviously, is not variable in heights, so should be included.