The woman was attacked by a man at St Denys station in Southampton just after 00:00 BST.
Hampshire Constabulary said her attacker fled the scene in a vehicle and have appealed for witnesses.
The arrested 18-year-old is being held on suspicion of rape and attempted murder and remains in custody.
A man has been arrested over the "violent assault" and rape of a woman in a railway station car park, police have said.