An additional 1,760 passengers an hour will be able to use the Luas in each direction on the Green Line.
The Government has given the go-ahead for a €100m plan to boost capacity on the tram network.
Eight extra trams and lengthening the existing 26 Luas vehicles will see expansion of the line that currently runs from Dublin's south county to St Stephen's Green.
Recent surveys by the National Transport Authority (NTA) indicate that the route is currently operating at capacity during peak periods with crowding between the stops at Balally and Ranelagh.
The planned investment follows on from the Cross City extension of the Luas due to open next month.
Transport Minister Shane Ross said the project to enhance services on the Green Line would begin next year and, combined with the Cross City Project, would "add greatly to the choice and experience of the travelling public and ease congestion in the city".