The number of vehicles travelling the route is up 6,300 on last year
The M50 in Dublin is now clocking up eight hours of rush hour traffic a day.
That is according to figures from Transport Infrastructure Ireland (TII).
The number of vehicles travelling the route every day is up 6,300 on last year's figure.
Morning peak levels are being recorded between 7.00am and 10.00am, while in the evening rush hour now runs from 3.00pm to 7.00pm.
An analysis of traffic data supplied by TII to the Irish Independent gives a snapshot on how the M50 is faring.
It based the analysis on volumes on the first Wednesday of October in 2013, 2014, 2015 and 2016.
It shows numbers are steadily growing year-on-year.
On the first Wednesday of October 2013, just over 133,345 vehicles used the road. The figure had increased by 19% for the same day of 2016.
The Irish Independent environment editor Paul Melia says the roads are getting busier earlier.
"People are leaving earlier to get to work, numbers then again in the evening peak are up as well...so basically what we're seeing is that there's more cars on the road, there's more vehicles on the road, they're on the road for longer than they would have been four years ago", he told the Pat Kenny Show here on Newstalk.
"The problem with this is that the M50...cannot be further expanded because there's no land to expand it on either side of the motorway".
"The options really are you allow it to continue as is and turn it into a car park - or get cars off the road".
"The solution isn't really just getting cars off the motorway - it's to offer an alternative, and it's to offer public transport".
He says a 'Public Transport Day' could be the answer to get proper feedback.
This comes as a draft report reveals parts of the rail network in Ireland could face closure without additional government funding.
The warning is contained in a draft report which focuses on possible solutions for the future of Iarnrod Éireann.
The document, seen by The Irish Times, says that although the number of people using trains is on the rise again, Irish Rail could still lose about €11m this year.
Irish Rail worked with the National Transport Authority (NTA) to compile the report, which also estimates that the company needs investment of more than €600m over the next five years.
However, the NTA adds that the report was prepared before the budget spending allocations were announced.