But that would involve a reverse for services to Newmarket, Ipswich and Norwich and it wouldn't serve any new Cambridge South station. I just don't see where the land is for new curves.
A southerly approach is just a lot simpler for through services.
Hi camflyer, I take your point, but to dive south from Cambourne into Cambs Central just does not look right and will miss my target of connecting the science parks. The Newmarket/Ipswich and Norwich through trains would not touch Cambs Central they call at Cambs North.
There would be no reversing EWR trains at Cambs Central, they could start and stop there. But I would start EWR trains at Cambs North, run a shuttle between Central and North. No new heavy rail station Cambs South, light rail/metro service to Cambs Central into a mini interchange. Coming onto the Norwich - Stanstead line at Coldhams Junction you could in future have 2 tph locals from Mildenhall (proposed large development) and 2 tph from Ipswich one GA and one EWR and perhaps one freight tph. One local to North the other to Central, EWR to North and GA to Central. The hourly EWR train from Norwich calls at Camb North on its way to Oxford.
You have direct hourly Ipswich to Oxford and Norwich to Oxford EWR as per the spec, as well as 1tph local from Mildenhall running into Camb North all current stopping services there will feed passengers onto EWR.