At the tunnel entrance portals the OHLE will cease, and within the tunnels its an overhead rail, what are the arrangements for smooth transition of the panto from one to the other? Something amazing from the Swiss?
It is worth noting that the Rigid Overhead Conductor, isn't just an inverted juice rail type installation, it has got a contact wire set in it that the pantograph is in contact with, it simply prevents the need for catenary wires and most of the tensioning equipment. As for the physical transition, I expect that it'll be something like this (the imaginatively named transition bar), the contact wire simply runs into the ROC, the other rails helping to ensure that there is a smooth transition
"I don't make mistakes. I make prophecies which immediately turn out to be wrong." "And now, excuse me while I interrupt myself" - Murray Walker
Greg Tingey's explanation on LR - '[T]hey simply string a wire parallel & very close to the overhead “rail” for some distance, with the rail slowly rising & the wire descending, so that there is a seamless transition from the p.o.v. of the moving pantograph.'
Hi! Same system exists in Paris, RER line C, between Invalides and Austerlitz stations. Most of this tunnel section has a very narrow gauge and has been electrified in the first half of last century: due to the lack of space, the system of the "rigid catenary" has been chosen.