Currently from South to North a third of the tunnel is double track , a third is single track with the second bore in place but not equipped .
A third is only a single track tunnel with the parallel exploration adit providing the emergency egress .
Currently from South to North a third of the tunnel is double track , a third is single track with the second bore in place but not equipped , and a third is only a single track tunnel with the parallel exploration adit providing the emergency egress .