Here, it becomes difficult.
Travel may be a human right, but there is also some liberty in contractual matters. Can one party A be obliged to enter a contract with another party B, in this case be obliged to sell B a ticket and honour it by transporting B in accordance with it? Bs right to travel is not taken away from her if she has to use other means of transportation like a bus, train or even her two legs. The right to travel does not mean the right to the most convenient means - or does it?