The N9/M9 route used to start in the centre of Naas ("Nace"), a pleasant town about 25 km from Dublin. In 1993, the first attempt to upgrade the route occurred with the opening of the M7/M9 Newbridge Bypass, a motorway scheme that extended the M7 Naas Bypass west and south. The 9 route now started at the junction with the M7 and rejoined the regular road network to the south of the village of Kilcullen. It constituted 6 km of motorway and around 110 kilometres of variable quality single carriageway road.
By December 2009, the motorway section between here and north of Carlow was completed. Castledermot was finally bypassed, a town that has struggled to keeps its roads from falling apart due to trucks rumbling by. Roadworks that dragged on for years were finally finished a few months before and the new road couldn't come quickly enough to prevent the new pavement from crumbling again.
The 9 route then passes through the town of Carlow
, a community that has seen huge growth in the commuter market due to its proximity to Dublin and cheaper housing. Carlow is the crossing point of the N9 and N80 routes, the latter being a strategic cross-country route running northwest to southeast from near Athlone in the midlands to Enniscorthy near the coast.
The Carlow M9 motorway bypass opened in May 2008 and finally relieved the large town of its congestion problem. It winds its way to the east of the town with one intermediate junction. With this road opening, the M9 was no longer simply a tiny spur and was on its way to becoming a major strategic route, though the two extant sections were as yet unconnected.
South of here, the route splits into the N9 and the N10. The N9 continues to Waterford via the shortest route, while the N10 is a deviation via the historic walled city of Kilkenny. The route deteriorates to its lowest standard as it goes through Thomastown, winding through narrow streets.
In September 2010, the motorway finally bypassed this whole section, running quite close to Kilkenny, making the N10 deviation less necessary, though the numbering was be kept anyway.
The final leg of the route, from the N10/N9 junction to Waterford, was a narrow winding route taking you past cows and sheep. It was one of the lowest standard single-digit National Primaries in the country. In March 2010 this section was also replaced. The new route connects directly with the Waterford City Bypass.
With average daily traffic levels of less than 10,000 vehicles along much of the route mileage, many would wonder if a motorway is even needed along this corridor. Indeed, until 1999, only single carriageway bypasses of its string of towns were planned. An early scheme, the Moone-Timolin realignment, dates from this period. It was only later that the decision was taken to make the whole lot a new dual carriageway - and later motorway was specified - in the name of future proofing.
Kilcullen Motorway Services Area is due to open in October 2019.