I'd noticed that Alan Moon's suggested "second edition" rules didn't seem to be posted here. The Additional Rule was supposed to be one that didn't make it into the original rulebook, and the Rule Changes and Variant Rule were new:
If all train spaces of a track type are full, the Track Cards of this track type are unplayable. A player may discard an unplayable Track Card at the start of his turn and draw a replacement (the unplayable card should be removed from the game).
1. At the start of the game put 6 Stock Cards on the bottom of the deck. This means that the last Score Card cannot be one of the last six cards in the deck.
2. Deal 5 Stock Cards to each player at the start of the game instead of 4.
Players may not draw a UP Stock Card. They must always draw one of the four face up Stock Cards or the top card from the deck. The only way to acquire a UP Stock Card is to trade one Stock Card in your hand for one UP Stock Card.