I think unfortunately this is normal for the game, seems like it has a memory leak which eventually exhausts the 32 bit address space. This kept happening to me with the original CD release back in the day, on several computers on different versions of Windows, then with the original CD running in Wine on Linux, and also with the GOG release.
On an old Katmai P3 (533MHz), the effect was rather dramatic as back then we hadn't got gigabytes of RAM. When this crash happened, the system would be about frozen for a couple of minutes busy rattling the hard-drive as it recuperated from having more than 2 gigabytes RAM already allocated (and swapped) when finally there was no more.
Save the city often. Wish there was an autosave feature at least.