Thanks for all the replies.

I was trying to establish which way it is considered for a RTW routing, 'presuming' that this would count for the required crossing the Pacific. I think I can safely assume it's Trans-pacific. What route it actually flies is irrelevant in comparison to what way CO consider it for a RTW.

FWIW the SQ flights to EWR are classed as Trans-pacific. When I flew this a few weeks ago it did indeed cross the top of the pacific. However, for return EWR-SIN, after initially going over the North Pole they now fly across the pond, over the UK and down to SIN due to more favorable winds.

SQ have actually just added a US$500 surcharge for people using the EWR flights on a RTW .