Here's a bit more information (in French or German) on this particular project (part of the national "Bahn2000"modernisation program, involving billions of dollars of improvements.)
Translated (badly) from the Bahn2000 web site.
"Between Coppet and Genève an third track will be constructed adjacent to the existing two existing tracks. Regional trains in both directions will use the track closest to the lake. The two tracks on the Jura (mountain) side will be for exclusive use of inter-city trains. At Creux-de-Genthod a passing loop will be constructed to allow regional trains to run on 30 minute headways."
[Note that when these guys schedule a meet, they make it
_every_ time. The amount of traffic they regular _schedule_ over
single track sections shows what total horseshit of UP and friends
fabricate about "track capacity" being "exhausted" at 12
trains/day or whatever when they're attempting to extort public
money to to their own deferred maintenance and reinstate their own
unwisely ripped-out infrastructure for them. And of course the
entire existing Caltrain service could be run on a single track
with just a couple of passing loops along the way: no "single
tracking delays." But I digress...]
"Modernisation of Coppet-Genève will be accomplished in two
phases. Starting 30 May 2001 IC2000 double-deck trains will enter service
Genève-Lausanne-Fribourg-Bern-Zürich. This means that from that date
various road and pedestrian overcrossings must be reconstructed for
the larger loading guage. (0 in Karte rot/gelb eingezeichnet).
In 2005 the third track Genève-Coppet will enter service, marking
completion of stage 1 of the (national) "Rail 2000" program."
The 33.5km long third track will be constucted along the existing
line with highest concern for environmental protection and the comfort
of residents along the line. Noise control will receive particular
For example the stretch through the "Grand Mont-fleury"
district of Versoix illustrates various noise mitigation
measures which will be used (built or planted) along the entire
Third track, approach to Genève. Construction of the platform and
retaining wall adjacent to the botanical gardens.