I have been to a few events and seen the gridlock first hand (Ed Sheeran, Anthony Joshua) It really can not be exaggerated how bad it can get. there was a taxi line of hundreds of people at 2am after the boxing.

They keep saying they increase train capacity at major events, but they never do, always the same services running at the same times.

Giving the proximity of the train station, this is a massive own goal, A significantly increased service in all directions would basically solve the issues.

At the same time I do not have much sympathy for the drivers who expect to be able to drive right into the city centre 30 mins before and drive right out 30 mins after, if you do not have to take your car then do not.