Capacity is limited on many of Dublin's radial routes and upgrades are well overdue in many cases. The N7 Naas Dual Carriageway was widened to 6 lanes in 2006, and had many new interchanges added. The N4 Lucan to M50 widening scheme opened in 2009. The N2 Ashbourne-M50 scheme opened with a few kilometres of 6-lane standard from day one in 2006, the only road in the country to ever do so.

The M50 was thoroughly overhauled from 2006-2010 and widened from 4 to 8 lanes, though the southern segment between junctions 12 and 14 received 6 lanes and the long part down to Bray was not upgraded at all. In fact, the latter's late addition to the network in 2005 was marred by the short-sighted decision to have only 4 lanes when it should have been clear at that stage that at least 6 were on the way for the rest of the facility.

The M1 passed Swords to the east in 2003, but somewhat surprisingly, only 4 lanes were provided - though room was left for two more. In 2010, the part between the M50 and the Airport was widened to 8, in 2011 the part from the airport to Drinan was widened to six, and in 2012 the six-laning was extended north to Lissenhall.

However, no work has yet been done on providing more capacity on the busy N3 at Blanchardstown, and the M7 urgently needs to be six-laned from east Naas as far as the M7/M9 split east of Newbridge. As of late 2015, work on this latter part is scheduled to start in April 2017. Congestion is also severe on the M4 from Leixlip to Maynooth, and on some parts of the M11/N11. To link with this latter part, the southernmost segment of the M50 needs to be widened also.

In the long run, more M1 widening will be needed, as far as Balbriggan. Proposed road widening projects are marked in purple on the below map.

Update Nov 2015: A draft Transport Strategy for the Greater Dublin Area 2016-2035 has been released. On p.74, most of the proposals listed on this page are listed. So far, only plans for the upgrade of the N7 Naas Dual Carriageway (from the M50 to Naas) have been publicised.