Intercity, Regional and peak hour T9 semi-express services use the outer express track pair of the quad between West Ryde and Epping in tandem with freight. That is unlikely to change when the full quad from Strathfield to Epping is completed. I doubt if they would ever be used exclusively for freight like the SSFL.Linto63 wrote: ↑Thu Jan 25, 2024 7:42 am Northern Sydney Freight Corridor program was completed in 2016 with third down line opened between Epping and Thornleigh. There is a Stage 2 proposal to quad Rhodes to West Ryde and triple Thornleigh to Hornsby, but this is more to accommodate extra freight services than allowing for passenger services to operate at higher speed. Once again an increase in line speed on a 6-10 kilometre section would only bring small, if any, reductions in journey times.
It's debatable whether the maximum speed limit for passenger trains would ever be increased to 160km/h on this stretch of line, although it would be capable of that. There's no reason why the maximum speed couldn't be increased to 130km/h with the upgraded signalling provided there are sufficient headways between freight trains and following passenger trains. From Epping to Hornsby would be a different matter because of the winding alignment. I suggest that there would be a significant difference in journey times compared the current lumbering speed limits. It would at least contribute towards lowering the average speeds between Strathfield and Hornsby.