I think segregation is the wrong approach. I'm going to quote:

"There has been a 20% increase from the previous year in reports of violence ( including of a sexual nature, harassment etc.)"

So we are talking about violence, including sexual violence. If this violence is aimed towards gay men would be right? No. If violence is aimed towards brown men would be right? No. Trans? Nope. White men? Of course not. Violence, includind sexual violence is wrong regardless of who do it and to whom. So the women only train would leave unprotected the women who has to take other train because maybe are late, gay men, brow men, trans, white men, etc. And if perpetrator is a woman, it won't work.

That is a bad solution that doesn't focus on the root of the problem: tolerance to certain forms of violence. The fact is, we don't take seriously some forms of violence until that violence escalates and sends someone to hospital. But if a group of young men harash another white young men because, let's say, they consider him a beta for not being sexist enough (or being poor) is it ok? If it is "only insults"? No, it is quite serious. But people tend to look the other way because they "don't want trouble". And they are partly right. The sensible thing to do is call the police, not get in the way of danger themselves and maybe escalate the situation to something worse. But here is when it comes the trouble, if they leave the train before the police arrive, nothing is done. If the police come but don't take this seriously because "they are just kids/drunks/whatever" and, of course, you are not going to "ruin their lives over something so minor". then people learn that calling the police is useless. Same happens with women. Many people are uncomfortable about doing something over "just graving an ass".

The solution is to start taking these things seriously and yes, being willing to ruin some young men's lives over that "minor" violence that would escalate over time. Some women too, to be fair. And maybe add cameras so even if they leave the train, they can still be caught. Start with fines for the first minor offenses, and add punishments that say "we don't tolerate violence in any form". Sure, an idiot teenager that grab an ass once shouldn't go to jail. But he should be punished with a fine and community work to learn that it is not ok. And a drunk man should be also punished accordingly, without reducing his sentence for being drunk. If you can't control while drunk, stay home in the same way that you don't drive drunk.

Let's face it, most men would also like to be free from violence and won't be affected by taking violence seriously because they have never been violent. Violence is not a masculine trait, is a bully trait. If you stop a bully when he attacks a girl or a woman, then he won't be able to attack boys and men either. If you stop a bully when he attacks boys or men, he won't be able to attack girls and women. Focus on the key issue: violence. Sexist, racist, homophobic, aporaphobic, whatever the reason, stop violence and stop making excuses for it.