Walk-outs on June 21, 23, and 25 have been organised by union RMT following a breakdown in negotiations over pay freezes and job cuts.
Tens of thousands of workers, including staff from South Western Railways and Network Rail, are expected to take part.
The news has been met with mixed reactions from commuters, with some speaking out in support of the striking workers, and others voicing concern about the impact on rail customers.
Passenger Alice Cox uses the railway for work, and believes the strike to be a 'necessary evil'.
She said: 'It has changed my plans and has meant that I do have to replan a work trip - but that is changed plans, not ruined plans.'
He said that while the fuel price rises have affected him more than the strikes will, he believes that the industrial action will have an impact on commuters.
Ian said: 'You can imagine it's going to be difficult for other people, being late for work. It isn't good.
'I don't think they always think about everyone else - other people don't need to suffer.
'You'd quite like to think that in this day and age, they could come to an agreement.’
Hamish Brown, who travels from Chichester to Portsmouth for work, said: 'It's going to be very inconvenient.
'For me, it'll be just another car on the road.
'The result of this is a whole range of effects - not only for going to work, but for those who go to rail stations for coffees.
'I think it's absolutely awful.'
Grace Campbell, a civil engineering apprentice from Fareham, said: 'I get why they are doing it. It's annoying but it's got to be done.
'The rail people have got to do what they've got to do.'
Portsmouth resident Jane Dole said: 'I think it's quite difficult to say what's right, and we've got to look at every point of view.
'Perhaps there could be another way around it.'
Another commuter said: 'I do think they have got real grievances, but I'm not sure this is the right way to do it.'