Yep - what dannygee said. I remember a Durham 64 broke down, about a year ago, so our 22 stopped and picked up most of the passengers as most of the Durham part of the East bound 64 route is just a short walk from the 22 route, anyhow. In situations when a road has temporarily closed, a longer distance bus will detour to miss the blockage, though the success of this does really depend on the driver's local knowledge! It's usually better to miss 2 or 3 stops and finish the journey 15 minutes late than not finish the journey or end up an hour late though.

In longer term situations, it has been known for operators to agree to honour each other's tickets, but that takes some prior agreement! What seems to happen more often with major infrastructure problems, such as the bridge problems at deerness, earlier this year and various incidences of roads being blocked by planned roadworks is that the local authority steps in and commissions a shuttle to bridge the gap in the service in some way.