Never knowing when - or if - you'll get where you're going is becoming S.O.P. for commuter and intercity rail. I've taken to carrying a pack with me on the daily commute to work. It's like a '72-hour' pack, except I call it my '30-mile' pack, because that's how far it is to get home. Its contents depend upon the season, but suffice to say there's enough basic stuff in there so I can handle a day or two walk.

If this doesn't fit your image, you could do about as well with a soft-side attache case.