end to the good one. So take a metro to southern trainstation which is at the end of blue line and the name is Constitucion.
Anyway - how the trains works in Argentina,as I was told when I arrived from one argentinian friend,that actually u dont really have to pay,as u can get to platform without checking in and there is mostly no controllers in the trains.
These city inside of the city or better said megalopolis city trains are very cheap anyway - the cost its aproximately the same or even cheper than a inner transport of the city,so u pay really a from few cets to maximaly 2 something pesos (like 10CZ or 40euro cents)to get somewhere on the place where u can hitchhike. I actually created a video from a train saying more or less the same as I wrote here :)
Then when u get to Hudson trainstation,(be carefull to dont pass it - as ometimes there are not seenable the names of the stations,but for sure the people will tell u.),cross the railway to oposite direction to Mar del Plata. Do not get out to highway or u end up like me ... Well this video was made before 2 police ladies came and sent me away without telling where is the next exit where the cars exits to highway... The people in Buenos Aires in general dont like to give u the whole information,just a partial one...
<center> This is correct direction,but wrong spot - in the middl eof the highway. Cars goes too fast and they will come police soon for sure </center>
So get trough the railway to the other side and then u would see the road which looks like road going to country and another one going under the bridge. Take the country one. There is no marking,but at the end after walking about 2 km u will find out that its an exit to highway and there can hitchhike and people go slow,so u will be lucky for sure in some point :)