I honestly think it's ridiculous our public transportation is so unsafe to warrant this, but if it's necessary, then so be it. But if we're going to make women only carriages we should make an equal number of men only carriages, because not all women will use the women only carriages and i don't want my available commute space compromised because authorities can't keep public spaces safe for women.
I know it sounds a "but what about men" comment, but let me explain why. At my gymn, we used to have an open space for everyone. Then they decided to segregate about 1/3 of the space and make it ladies only while the remaining space was to be for everyone. The result is that, despite having machines available in the women's area, women want to be in the everyone's area all the time while the women's area is usually empty. The result is that there's no space for everyone to train in and men just have to queue to be able to train at peak times, usually in the late afternoon. We all pay the same, we all need our exercise, why are men having less ? Because we share the same gender with rapists ? How is that my fault ?
I can see the exact same thing happening with transportation. You limit men's available commute space on account of having an unsafe space for women, then the women's carriage goes empty while the everyone carriage forces everyone to be up against everyone. This is unacceptable. I have been sexually harassed as a man in public transportation too and while i recognize it's not as bad for me as it is for women, because it only happened a few times, it always happened by forcing me to be smushed against a ton of people.
I would prefer if everyone respected everyone and we could live like civilized people together in an equal and safe society, where nobody was threatened, harassed or raped, but if we're going to start sex segregation at least do it in such a manner so that everyone has equal amounts of space and opportunity to carry out their lives without being inconvenienced. If we segregate spaces, make x space for women, x space for men and x for everyone together. None of this special places just for women while everyone pays the same crap. That way if the common area is too full, i can just move to the men only area and that's it. If we can't be decent, at least let's try to be fair.