Interesting that Siemens seem to still be willing to support a Win 3.11-based system for at least one operator. That said, this looks like it's a third-party doing that work but Siemens must be tacitly allowing the third party to try to do so, as they'd have a complete stranglehold on the design, software and hardware underneath it.

I worked for a rail operator and the driver interface systems of our locos (from other suppliers) were running on WinXP. We wanted some changes and feature upgrades, but the supplier said it was obsolete and they would not do any code changes to the WinXP software. Instead, they were telling us to move to a QNX-based version of it (which came with all of the fun joys of ensuring feature and interface equivalence for both the system and the human-computer interfaces). This was even for old locos, where moving to the QNX-based system wasn't just about running the same front-end software on a different OS, but in some cases was a fundamental hardware design upgrade (i.e. moving from a dumb terminal with a rack of hardware in a cupboard to fully integrated computers in the dash), which then meant making it interface with other hardware systems that may not be designed to talk to it. In some cases, those additional systems had to be upgraded. It was well in to 8 figures of work to do.

I am surprised that Siemens have, in some degree, allowed ongoing support for this. Whichever operator uses it must be fairly big in order to bend them to still actively manage it.