4700mm

My example of 66001 arrived yesterday and whilst it looks and runs fantastic I have had a couple of issues. The first is a high pitch whine when moving and wagons coupled to it will derail on 2nd and 3rd radius curves, this seems to be caused by the coupling having restricted movement so its pulling the wagon off to the outside of the curve and off the track.

The peco structures are based on Mk3 equipment although I can't say which version which gives a nominal contact wire height of 4.7m or 4.72m above the rail level. Designers are allowed to bring the contact wire down to 4.165m to clear tunnels, bridges, signals etc.

Structures are designed to the requirements of the site. Designers use a general arrangement drawing and select the parts needed for their requirements, the height of the portal and the length of the portal boom will vary from structure to structure.

I think that should be EN 50163 which gives the highest nominal DC voltage as 3kV with a note that says "Future d.c. traction systems for tramways and local railways should conform with system nominal voltage of 750V 1500V or 3000V.". I cannot see anything specific for street running.

I'm only an OLE person so not competant to comment on most of the dimensions but I noticed you're missing the dimension of the running edge to the platform offset which group standard GIRT7020 gives as 730-745mm for most locations. Scaling that down should be fine for P4 but would need to be increased for curves.