As passenger train service and some airlines teeter on bankruptcy, there is growing concern that consumers may be left holding the bag with worthless tickets and rewards. The best defense is to use credit cards for travel expenses and not cash. When it comes to air miles and other rewards, it is best to redeem them, or transfer them to another program, and not to sit on them. Credit cards generally provide consumers some leverage to get refunds from merchants. But most importantly, if the trains or planes stop, credit cards offer a much more convenient way to make alternate arrangements. When the doo-doo really hits the fan, you can bet the reward programs will be the first to go. As with any credit card reward program, think short-term. Use ’em or lose ’em may become routine advice in the next few years. Other programs such as hotel loyalty programs, and cards like Diners Club, enable you to transfer mileage from most airlines. Finally, think ahead. What would be your “Plan B” if Amtrak stops running or if US Airways is grounded? Monitor reservations and be prepared to make changes. Get your plastic ready.