A public consultation has opened to extend the DART from Heuston to Hazelhatch, including the Phoenix Park tunnel.
The Dart + project would quadruple customer capacity, deliver an improved electrified network and enhanced train performance.
It would also see train frequency increased from 12 trains per hour to 23.
Meanwhile, a feasibility study is being considered to build a new DART station Heuston West.
The Emerging Preferred Option is also compatible with future stations at Kylemore and Cabra, although the construction of these stations is not part of the current project.
A series of webinars will run next week to discuss the proposal with communities along the route.
