http://forums.steampowered.com/forum....php?t=1090651
There seems to be an issue where after playing the game for some time, it just locks up and then crashes. After some thorough research, it appears to be an issue where the game does not have the required setup to be allocated certain portions of your ram. In order to fix this, we must set it up so that it can get to this ram.
There are two fixes I know of, both involving modified .exe's, one worked for me while the other didn't.
Disclaimer: Modified .exe's are being used with Steam, which may be a hazard to your account. However, I asked around on the forum and many people have done it and said it's fine. In addition, I am using a modified .exe myself, so I sincerely believe it will be fine.
Fix #1: This .exe has the fix already applied to it
Link:
http://www.mediafire.com/?oqvgqywwemd
Replace your railroads.exe in "C:\Program Files\Steam\steamapps\common\sid meier's railroads" with the downloaded .exe
Fix #2 (Courtesy of Zorander and Warll): Manually apply the fix
Link:
http://www.mediafire.com/?lfgz2d0yytz
Copy your Railroads.exe from "C:\Program Files\Steam\steamapps\common\sid meier's railroads" to your editbin "3gb_enabler2 unzipped" directory
Go to your start menu and find command prompt, open it by right clicking it and pressing run as administrator.
Change to your unzipped 3gb directiory where you have editbin.exe by using the "cd" command. example: cd "users/coconut33/desktop/3GB enabler"
Type "editbin.exe /LARGEADDRESSAWARE Railroads.exe" (no quotes)
Extra Step for Vista 32: 4b. Type "BCDEDIT /set increaseuserva 2900" (no quotes). (Note: System boards vary; if 2900 does not work try 3072)
Copy the patched Railroads.exe back to your "C:\Program Files\Steam\steamapps\common\sid meier's railroads" to your editbin "3gb_enabler2 unzipped" directory
Note: If anything goes wrong for either fix, don't worry. Just delete the railroads.exe from the folder and then launch Railroads. It will automatically download the original steam copy again.
Best of luck.