DOO only really works well on suburban services where the overall staff presence is relatively high.
It does depend on what other staff are present on the train, and what their level of safety training is.
There are certainly examples of incidents where something has happened and the second safety-trained member of staff has proved their worth. Likewise examples of DOO services were the lack of such a member of staff caused things to go badly wrong - Lewisham and Peckham Rye spring to mind for starters, and both of these were in suburbia.
I’m more relaxed about DOO than some, indeed my local rail service has been DOO for as long as I can remember and I can’t say that the lack of a guard has ever really caused a problem that I’ve personally been affected by. I do, however, take the view that if you’re going to have a second person on the train then we might as well get the best value out of them, which is as a fully safety-trained guard, rather than something like an OBS which is really just going through the motions.
To be fair, much of what goes on in the industry is “theatre”, however there are good reasons for this, namely that if staff are totally drilled in following a specific routine, then they’re less likely to get caught out when something unexpected or unusual happens.
