How does one evaluate a “locomotive” (rainbow card) in “Ticket to Ride?”

Question

A locomotive or "rainbow" card can be a train of any color you want. That's good, and that's the reason why you can draw only one rainbow card from the board, in lieu of two regular cards from the board, or from the deck. (You're allowed to draw two cards, one or both of them "rainbow," from the deck because it's random.)

As a newbie, my feeling is that rainbow cards are more valuable if your routes need five or six trains of one color, and less valuable if there routes are shorter, and/or or can be spanned with multiple color combinations.

So how do you decide when to take a single rainbow card for sure, take two (other) "known" cards from the board,or draw two "random" cards from the deck?

Answer 1

Here are three sources of pain you try to avoid:

• Drawing only one resource card instead of two
• Drawing resource cards that you will never be able to spend
• Losing a race to build a link you want (an opponent gets there first, or the game ends first)

The single rainbow option is the only way to get stuck drawing one card instead of two, but rainbows are always spendable and awesome for winning races. I like to keep one or two on hand in case I find myself in a surprise race with an opponent, so after the first few turns I'll take one whenever I don't have one. I usually try not to spend them on very long links unless I think I'm in a race for those links - instead I'll just take known cards of that color when possible, and unless an opponent tips their hand by also taking known cards of that color, it's unlikely they can collect the requisite number before I do. (In contrast, for a short link it is likely they've randomly picked up one or two cards of that color.) I'll also start taking single rainbows more often at the end of the game since they're guaranteed to be usable.

Early game, I usually draw random cards - the main thing I'm risking is losing a race with an opponent, but on a wide open board it's often both unlikely that an opponent takes exactly the link I want and not too terrible even if they do since I can reroute around them. Draw randoms enough and you'll even end up with a rainbow or two to fall back on in hard times, and there are enough links of every color (and gray links) that you'll probably eventually find a use for whatever you draw. However, random cards get less and less attractive as the game progresses - with fewer links left there's more of a chance that an opponent wants the same one as you, or that you'll draw cards that you never find a use for.

When the known cards include colors you need, taking them is always an attractive option. An obvious downside is that you lose the ~1/9 chance of landing a random rainbow; a less obvious but potentially larger downside is that you give your opponents a hint about what you're planning to build. If you don't think your opponents will effectively use that against you - they can't figure out what you're doing, they don't have the resources to stop you or it's not sufficiently in their advantage to use them, they're not that kind of competitive, etc. - then taking known useful cards is usually the best choice. But occasionally you take that red card and then an opponent jumps on the opportunity to build the red link you wanted; not only is your link now gone but the red card is now probably less useful than a random one.

Answer 2

A lot of my reasoning is very similar to Benjamin Cosman's, but I think I've got enough to say that it's worth making a separate answer.

Rainbow cards are valuable, but they're not normally twice as valuable as other cards. For this reason picking up a face-up rainbow card is not normally a good move.

The best way to pick up rainbow cards is to pick up blind cards, as then you're still getting two cards per turn. Ok, so you'll mostly get other cards, but this shouldn't be a problem. Almost any card you pick up in the first 80% of the game can be used; either you'll need that colour somewhere or you can use it on a grey route.

My order of preference is:

1. Pick up two blind cards, unless any of the below apply
2. If I need a route that is 5 or more (and I don't have that many yet) pick up face up cards that meet that colour (or those colours). If that's only one card, then my second pickup will be blind.
   • NB If the route is 5 long but has two different colour options, I will only pick up face up cards if I'm nearly there on one of the colours and nowhere on the other.
   • NB2 There's not too much risk of giving away to your opponents that you're after that route - if they want the route they'll be picking up those cards too, so you need to get them before they do!
3. If I need a route because I'm about to be trapped, pick up that colour.
   • NB This is to be avoided if possible as it lets the opponents know that you want that route. If you can make that route by using up rainbow cards, it's probably better to play that rainbow card
4. Late on I'll pick face up cards to make my four, three or even two long routes, to make sure I get them. These will be colour cards if available, rainbow if not.
5. Late on, after counting how many cards are in my hand and how many trains I have left to play, I'll start picking up cards to make sure that I don't have 5 odd cards left at the end when I want to play a 2-long route on grey. Ideally when I run out of trains I also run out of cards.