I’m not sure this will be the exact redundancy setup, but this is from a fairly recent Doppelmayr publication (8/2016) and has been implemented in a few European builds as of the date of the article. Looks like 3 possible drive mechanisms. Pretty impressive.
“With Doppelmayr’s Recovery Concept, dramatic and expensive rescues are no longer necessary. Cabins with passengers remain comfortably intact and would simply be returned to the station with one of the Concept’s alternative drive mechanisms,” says Tom Sanford, VP Sales of Doppelmayr USA.
Recovery Concept. Image by Doppelmayr.
Major features of this system include:
- Main drive mechanism has an auxiliary motor in case of primary motor failure
- Coupling can be detached from bullwheel to allow emergency drives to take over in case both primary and auxiliary motors fail
- Each bullwheel is equipped with an emergency bearing allowing rotational movement between emergency drives on either side
- Special tools installed which lifts the cable back to normal position in case of derailment
- Special tools, such as permanent crane facilities, to remove blocked cabins
“We’ll never completely eliminate the need for rope rescues but, with Doppelmayr’s Recovery Concept, nearly all of them are now prevented,” says Sanford