I recently attended a Northern Conductor Assessment Day
The sift - the candidates present were people with a proven track record of shift work often involving potentially hostile customers.
The day consisted of two group activities (both railway related, nothing too ridiculous), followed by a face-to-face interview for candidates who passed the first stage. Out of 10 candidates, 3 progressed to interview and as far as I am aware these 3 all passed the interview stage.
Advice:
Dress the part
Make a clear and decisive verbal contribution in the group activities, but while being supportive and listening to fellow candidates. Don't talk over anyone or be argumentative.
Remember that the whole day is an interview, so for example, if the HR lady 'accidentally' drops her papers on the floor in front of you, or someone is struggling with a door, you probably want to react to that positively and helpfully.
Make an effort with other candidates
Smile
Do your prep for the interview and demonstrate this if you can
Don't stress about the interview, if you get to that stage you will find they are pretty supportive and helpful
The interview was some standard competency questions where you provide examples, plus a few questions about how you would handle certain situations. They then make sure that you are okay with certain elements of the role and give you more information about the role.
Have a couple of sensible questions prepared for the interview
All the Northern people that were there came across as decent, professional, friendly etc, they aren't trying to catch you out and overall it was quite a nice experience.