Due to an Operational Incident between Anytown and Beeford, train services between these stations may be Cancelled, Revised or Delayed by up to 90 minutes. Replacement Road Transport is in operation between these stations. Disruption is expected until 16:00 today.
Why is that, or variations upon insufficient? Per ATOC (RDG) guidelines that is a perfect disruption message for Passenger Information During Disruption. It says what the problem is (operational incident), the impact of that problem (cancelled/revised/delayed) and Advice to passengers for alternatives etc. For any kind of serious disruption that would have to be reviewed and updated every 20 minutes, or when significant changes to impact or advice occur; whichever is sooner.
The problem with PIDD is it's actually quite old now and doesn't use Plain English best practices.
Firstly, and a bit pedantically, you can't start a sentence with "due to" as it creates an adjectival phrase.
Secondly, the form of words tells people what the excuse is first, and follows with the advice. As has been pointed out upthread, it's more important that passengers know what they ought to do rather than the reason. It's good practice in any form of communications (particularly when dealing with comms in an information-saturated environment) to front-load the most important information.
That isn't to say the reason isn't important. People have paid fares and deserve to know why their service isn't going to be delivered as advertised. The aviation industry is at least as safety-conscious and image-conscious as the railway - and with a significant portion of users having a fear of using it - but there's no harm in saying that something has gone wrong. "Operational incident" isn't acceptable; it isn't transparent, or descriptive. Just say what the problem is in plain English. A train went past a red signal so it was automatically stopped and investigated. A train mistakenly took the wrong turn and now needs to reverse. A train driver got given the wrong stopping list. A guard was left behind at a station by accident.