Irish Rail is planning to introduce a high-speed service from Cork to Dublin which will slash journey times to just 2.15 hours - 15 minutes less than the fastest service currently offered and half an hour quicker than travelling by road.
A morning non-stop service will be introduced after Easter, and average journey times across all services between Dublin and Cork, Kerry and Limerick will fall by up to eight minutes from 2016, the Irish Independent has learned.
The quicker times will be possible following the completion of a €10m upgrade of an 80km stretch of line from Hazelhatch in Kildare to Portlaoise.
The works include removing and replacing up to 80,000 tonnes of stone ballast which will allow trains travel at higher speeds. This ballast supports the track, but deteriorates over time which impacts on speeds.
The works will be carried out at weekends and will be completed in November.
"We are investing €10m on track enhancements between Dublin and Cork," Irish Rail chief executive David Franks told the Irish Independent.
"The ballast disintegrates over time and that dictates the line speeds. The works will enable us in 2016 to have speeds of up to 160kmh.
"Over the next couple of years, we'll continue that across the (Dublin-Cork) route to get journey times down to under two hours. There are a couple of things we also need to do, including replacing five level crossings and a couple of bridges need to be renewed. A curve in the line also needs to be addressed.
"The intention is to knock a few minutes off in 2016 and 2017, subject to getting more funding. At the rate we're going, we think we can get between eight and 10 minutes out of timetable by doing the ballast. We can probably get 17 minutes from the timetable (over time) and that's our plan."
Currently, services travel between 110kmh and 140kmh, but when the improvement works are finished they will be capable of speeds of up to 160kmh.
The improvements will also impact on other services to Kerry and Limerick which will have lower journey times.
Prices will remain the same. It is hoped the changes will increase passenger numbers, particularly among business customers, as free wi-fi is on board and the journey will become quicker by rail than by road.
The works begin in March and will be organised to reduce the impact on services.
They will take place from 11pm on Friday night, and all day Saturday.
This will result in reduced frequency on the Cork-Dublin route on weekends and may impact on other routes.
However, there will be no works during busy weekends involving major sporting events of stadium concerts. Changes will be advertised.
The company said that a team of up to 40 workers will complete the works over 34 hours each weekend.