have a chat with a railway worker and also a signalman or two in the area in which you are staying to find out what is behind the rail timings, you might be surprised.

Things in rail get EXTREMELY complicated as rail signals are absolutely unlike road signals. I still remember the conversation I had with a signalman on the Chiltern Line which ran over LU metals between Amersham and Harrow, which made timing services for interchange at both Amersham and Harrow between Met and Chiltern trains anything from challenging to impossible, simply down to things like communication between two competing companies and incompatible signaling systems with completely different theories behind them. To this day DB Regio are still operating the same trains introduced by BR, no doubt in part due to requirements for operating over Met metals!

Obviously I don’t know exactly the situation in Brittany but I don’t doubt that enabling trunk services to meet every branch station service will not be possible simply from a temporal perspective, and holding trains at the platform can have devastating knock on effects for the whole line, connecting branch lines and all other services for the rest of the day because paths will be lost along with the need to maintain block spacing, assuming the use of absolute block signaling. It was the maths behind this that did for Northern Rail in the UK a few years ago. In short, it was mathematically impossible to keep the timetable AND maintain paths and spacing.

And at this point my brain starts to melt when I think back to those conversations had with railwaymen and signalmen all those years ago 😮