Yesterday, I saw the ad that Jag had mentioned about try to get people to pass down the carriage. It's brill, as this is a particular bugbear of mine, although the mime artists from a distance reminded me of a carriage full of Ronald McDonalds - which would be another nightmare.
The ad tells people that there isn't an invisible barrier stopping them from moving down the carriage and that it's difficult for others to get on if you do this.
Very similar to the 1944 "Please pass down the platform" ad by Fougasse
Love the no nonsense yet slightly philosophical strap line with this forties ad, "The more we are together, the more uncomfortable we'll be".
For more comparisons between 2004 and 1944 check out my post from the 16th March.