Sid Meier's Alpha Centauri is crashing in the late game. Is it a resources problem?

I have been playing Sid Meier's Alpha Centauri since it came out, 20 years ago. I finally got around to playing on the hardest level. I am in the late game, just about the Gravship; it looks like I have a chance to win.

However, the game is now crashing. I would suspect a resource problem, except I have been playing exclusively on huge map of planet since the start, when my PC probably had only a few MB of RAM. My current laptop has 32 GB of RAM, which ought to be enough.

The only time I previously saw this was 5 years ago, when I made a custom sized map which was larger than the huge map. I now stick to huge, and have never once had a problem with the huge map until now.

I booted into safe mode, but terranx.exe won't run. I have tried a fresh boot, then kill a few processes, but with 32GB of RAM for a 1999 game, there shouldn't be a resource problem - unless it is a 32 bit thing.

Any ideas on how I can finish this game?