National Primary Route 50

Status : Incomplete

M1 Motorway Logo


Opened : 1990 - 2035

Motorway : 49 km (50.7 km by 2035)

The M50 - the most famous, most hated, most used, most congested, most upgraded, most essential road in Ireland. With 8 lanes for much of its length, it's by far the biggest road in Ireland. It's also unusual in that it doesn't replace an old route - there was never an N50. It's also an abused road - it was never even supposed to carry traffic from one part of Dublin to another - it's supposed to be the Dublin bypass!

This is hard to imagine when you're actually on the road. Vast numbers of cars are entering and exiting even at minor junctions such as Ballymun, Ballymount, Firhouse and Ballinteer. None of these junctions lead to a national route, so the traffic could not be long-distance. It's necessary to learn a bit about the origin of the road to understand what has occurred.

Back in 1970, the M50 Dublin Bypass was planned to form the urban boundary of Dublin. All major city development would occur within the boundary with areas outside it becoming satellite towns. The purpose of the bypass was primarily to connect the radial routes heading for other areas of Ireland to allow long distance travellers negotiate the city without having to use the street network.

Due to the slow pace of change in Ireland back then and the tiny trickle of money that was available for large-scale road building, it wasn't until the mid-eighties that any work took place on constructing sections of the road. It seems that a single-carriageway connection between the N7 and N81 Tallaght Bypass opened early but it wasn't followed by any more activity for a few years. Information on this is scant however.

Then a decision was taken which would have far-reaching consequences. The Irish government decided to allow a private company to build the expensive section of the M50 that would cross the Liffey Valley on a high bridge - and to toll it. This seemingly innocuous choice ending up shaping the lives of thousands of motorists for years afterwards.

After battling outrage from environmental groups opposed to the high-level crossing of the Liffey Valley, which is an area protected from development, the M50 section between N3 to N4 (junctions 6 and 7) finally opened to traffic in March 1990 (construction pictures). It opened under the name "Westlink", mirroring the Eastlink bridge in Dublin's docklands, though it is no longer referred to by this name. Just before its opening, pedestrians were permitted to walk the length of the bridge, the only time they would be allowed there before motorway restrictions came into force. Shortly afterwards, in May, the section from N4 to N7 (Junctions 7 and 9) opened. Junction 8 doesn't exist - it was reserved for a new M7 motorway which would run from here to Naas. This motorway has since been dropped and will never be built.

The 3-part road opening was completed in December of the same year when the extension to the N81 Tallaght Bypass (Junction 13) opened, presumably incorporating the old single carriageway section. The full N3-N81 section was referred to as the American-sounding Western Parkway. The toll at the booths was only 60p (76c), and traffic levels were only a few thousand cars a day. Nowadays, the area gets more traffic than this in an hour.

Soon after, work began on the extension up to the M1 so as to provide access to the airport. This finally opened in December 1996 and covered junctions 3-6 (M1, N2 and N3). This involved rebuilding Junction 6 to allow for the N3, the M50, a canal, and a railway line to all pass through the same point. The new junction was on three levels: the lowest level was the motorway mainline, the next level up was the canal and the railway, running on viaducts, and the final level was the roundabout and entry and exit ramps. The arrangement at the M1 was less than optimal: the M50 terminated at a roundabout, which quickly had traffic lights attached. Traffic making a left turn movement had slips, but a right-turn movement (i.e. M50 to M1 south, or M1 south to M50) necessitated coming to a stop at lights before threading one's way around a rotary (roundabout).

So far, all segments of the M50 had low capacity junctions. These were of the rotary type which provided for a straight-through movement only on the M50. Traffic on the intersecting road, such as the N3, N4, N7 and so on, had to stop at the roundabout and long queues developed. The British consultants working on the design of the road in the 1980s recommended freeflow junctions at these locations, but the Irish government decided to go with the cheaper option which apparently saved £50M (€63M). The roundabouts were signalised shortly afterwards and long tailbacks began to develop. Most infamous of all was Junction 9, the Red Cow roundabout, which was nicknamed the Mad Cow due to the frustration of the gridlocked motorists that threaded their way through it.

Most traffic on the M50 in its early stage had been the hoped-for long distance motorists and truckers, as well as industry making its way around the large industrial estates of southwest Dublin. Later, plans that had been on the books for years to develop "town centres" (code for shopping malls) in the areas outside the road began to come to fruition. First Tallaght, then Blanchardstown, then Lucan opened large malls between 1990 and 1999. The primary means of access to these centres was via the road network. These had a predictable effect: traffic volumes began to rise rapidly, by as much as 10% a year by the 2000s.

Congestion was starting to become intolerable especially near the main interchanges. Their poor design was causing huge tailbacks both on the approaches, and on the M50 mainline itself. With only two M50 lanes each way, any queuing traffic taking the exit or entering the mainline disrupted the traffic flow, causing speeds to drop and weaving. In response, as a temporary measure, left-turn ramps were added to the N4 and N7 junctions and certain other junctions received minor upgrades. This work was completed in 2001 but could only ever have a very minor role to play in congestion alleviation.

After a lengthy construction period, the M50 was extended from Junction 11 (N81) to Junction 13 (Ballinteer) and opened in July 2001. The road passes here through the foothills of the Dublin Mountains (which are really just hills), so the sides are yellow-brown granite cliffs with an Australian feel. The upgrade occurred in conjunction with some major distributor road construction in the Ballinteer and Sandyford areas to fuel their development for retail (Dundrum Centre) and office (Sandyford Industrial Estate) respectively. The strategy to increase the ease of access of the car to the areas was certainly successful, as they are now flooded with vehicles.

In September 2004, two light rail lines were opened in Dublin. The system was known as the Luas. The Red Line originated in the centre of Dublin and ran as far out as Tallaght town centre. Controversially, the line passed on a new bridge - but still at-grade - through Junction 9 (N7/Red Cow). Needless to say, this made congestion at the junction even worse, as well as delay the Luas's crossing by several minutes at peak times.

Coming relatively quickly after the previous section, construction of the final long section of the M50 began as soon as possible. Straight away the project ran into major difficulty. The remains of the long lost Carrickmines castle, which appears on ancient maps of Dublin but whose exact location was unknown, were discovered when the bulldozers moved in. Immediately a protest group of green activists moved in and occupied the site. Finally, a decision was made to excavate the remains, preserve as much as possible, and bury the rest. The site is in the centre of a roundabout and can be seen here.

The largest part of the extension project was the pair of very complex junctions 13 and 14, which were braided together. Junctions 13 and 14 are connected with parallel services lanes, while 14 provides access to Sandyford westbound and Leopardstown eastbound, with overlapping ramps. It's difficult to envisage, but the Dublin Eastern Bypass, a motorway connection to complete the ring around the city running from Sandyford to Dublin Port underground, is planned to join up with this junction too. How this would be fitted in to the spaghetti is anyone's guess.

The Junction 13/14 section opened early in November 2004. The rest of the stretch (Jct 14-17) was opened in June 2005 - minus the Carrickmines junction, on which work was late due to the protest. This one finally opened to traffic later that year in October.

A chronic problem the centre of Dublin suffered from was the very large amount of truck traffic attempting to access Dublin Port. Not only was this a great hazard to the safety and health of pedestrians and cyclists, it was also tearing up the road surface. The trucks utilised the Quays in the middle of town as an access route to the port which was to the east out in the bay. There had been a plan since the 1990s to arrange for an alternative access route that would allow a connection to the motorway network without using city streets. This plan was known as the Dublin Port Tunnel and was a motorway tunnel joining the entrance to Dublin Port to the M1 at Coolock. The road could not be built on the surface due to the destruction and expense that this would have incurred.

Work finally started on the very expensive project (€752M) in June 2001. The twin tunnels were 4.5 km long. A total of 2000 m was built using cut-and-cover, with the rest drilled through solid rock. Work finally wrapped up in December 2006, a full year late. At this time, the tunnel was re-signed as a new part of the M50. Under the new designation, the M1 from Coolock to the M1/M50 junction would be multiplexed with the M50. M50 traffic would approach Junction 3 (M1/M50) from the west, pass through the junction to the south, travel south on the M1 as far as Junction 2 (Coolock), then enter the tunnel and finish at Dublin Port (unlabelled Junction 1). In effect, the Dublin Port Tunnel together with an old part of the M1 became M50 Junctions 1-3.

The Eastern Bypass is a plan to complete the full M50 ring by extending the Port Tunnel from Dublin Port underground to Blackrock and inland, where it would surface and use a road reservation to get to Sandyford. This reservation can easily be seen in aerial photos such as this, here running northeast-southwest.

Such a project, though increasing the utility of the Port Tunnel greatly by allowing access to and from the south as well the north, would not only be phenomenally expensive, it would also greatly disrupt existing communities in south Dublin, as well as the road network in the Sandyford area. Part of the road network would be subsumed into the road, and considering it is already saturated with traffic, it is hard to picture how this traffic could successfully be rerouted. As mentioned above, the road would join the existing M50 at Junction 14 (Sandyford). This junction would be to be considerably redesigned in order to accommodate the new traffic movement. It would be much easier to just have the whole thing in a multi-billion euro tunnel, and it would be very surprising if any progress was made on this before 2040.

The only part of this confirmed to be taking place soon is a short 1.7 km section from the end of the Dublin Port Tunnel in the north docks to Ringsend in the south docks. It has not been confirmed if this road will be done as a motorway extension of the M50, or to a lower standard and different route number.

In summer of 2006, it was time to begin the long, disruptive process of upgrading the whole M50. Plans were made to fully freeflow the junctions with the M1, N4 and N7, partially freeflow the N2 and N3, double up the diamond interchanges at Ballymun, Ballymount, Firhouse, and add some left-turn ramps to the N81 and Sandyford junctions. Alone on the whole M1-Sandyford section, the Ballinteer junction required no upgrading, as it had already been designed to a high enough standard. In addition, the much maligned toll booths would be removed and replaced with an electronic tolling system.

As well as this, the road would be minimum 3 lanes each way, with an auxiliary lane between junctions - for a total of 8 lanes. There wouldn't be auxiliary lanes along the Firhouse-Sandyford (Jct 12-14) section however, since the road is constructed in a cutting.

Priority was given to upgrading the N3-N4-N7-Ballymount (Jcts 6-10) section, which was completed in 2008, though the N7 Red Cow junction wasn't completely finished until the very end of the year. Between 2008 and 2010, the remainder of the route upgrade occurred, which comprised widening from the M1 to the N3 and from Ballymount to Sandyford and the rest of the junction upgrades. On September 1st, 2010, the project was officially completed four months ahead of schedule. The M1, N2, N4 and N7 junctions received full upgrades to freeflowing status, while the N3 junction became partially freeflowing. The rest of the junctions had some left-turn slips added. Those junctions that consisted of a single overbridge had the overbridge duplicated.

The decision to fully freeflow the N2, instead of a partial treatment, was apparently taken immediately prior to start of work, as no announcement was made. In fact it only became clear that the junction had been upscaled once it took its final shape. The junction design could be called a partially-unrolled cloverleaf, or parclo for short.

The M1/M50 junction was modified to add the freeflow slips that would enable M50 to M1 and vice versa movements to pass unimpeded through the junction. The junction also provides access to the N32, but this is still subject to traffic light control. The important thing, though, is that the motorway to motorway movements are no longer so.

The monster rebuild of the M50/N3 junction presented some unique challenges. The canal and railway running through the middle meant that a normal reconfiguration of the rotary and slips could not be achieved. Instead the designers attempted to bypass the entire junction with a new N3 mainline. This meant that the old junction was now mainly just for local movements and access to properties abutting the junction. All M50 to N3 and vice versa movements were transferred to the new mainline to the north, as well as the new N3 inbound (to Dublin) mainline. The only notable exception was that the N3 outbound mainline still required negotiation of the roundabout, and its attendant sets of traffic lights. This prevented the junction from claiming full freeflow status.

A centrepiece of the upgrade was the removal of the toll booths on the Liffey crossing and implementation of an electronic toll system. A gantry was installed which could read license plate numbers and read in-car electronic tags. Motorists could install a tag, in which case the toll would be €2, and link it to their car. The camera would read the tag and the plate, and charge the motorist if there was a match. If there was no match, the owner of the car with those plates was considered not to have paid. For motorists who did not wish to avail of a tag, they could register their license plate with the system. The toll in this case was €2.50 instead. Finally there was the case of an unregistered, untagged car (or any car that suffered a misread). These cars had until 8pm the following day to pay on the internet or in a shop - but in this case, the toll was €3. Although the system suffered teething problems, with many thousands of misreads a day, the situation improved greatly over the years.

The N4 junction upgrade was a simple case of reconstruction to parclo. There was ample room to construct the necessary loops, but it meant that the left-turn slips of 2001 were obliterated. The improvement tied in to a 6-laning project for the N4 west of the junction that had been completed in 2009.

The infamous N7 interchange received a thorough and long-overdue overhaul. There were four major issues with the junction: the traffic-light controlled roundabout, the Luas line passing at-grade over two of the ramps, the proximity to Turnpike Road to the east, and proximity to the new junction to serve the Luas Park and Ride site immediately to the west. The solution was grade-separate the Luas P&R access and link this to the main junction, to convert the junction to a parclo, and to run the Luas through the centre of it between the carriageways. The Turnpike Road signal-controlled junction remains as an issue, with traffic having to come to a stop immediately to the east of the junction if the lights were against them. The Luas reconfiguration meant a complete rebuild of the nearby station and car parking areas. The old Luas bridge that used to carry the line through the junction was re-used to provide an unusual feature: a U-turn lane for N7 outbound traffic, should they wish to double back towards Dublin (having not had enough of it, presumably). Of course the opposite movement was not catered for.

The remaining junction changes mainly consisted of the addition of left-turn slips. In some cases only some of the four were added. The junctions that were of the dumbbell type were improved by doubling the overbridge so as to have one bridge for each direction, and removal of the dumbbell roundabouts and their replacement with signalised crossroads (example). This effectively converted the junctions into the diamond type. The junctions that received this treatment were 4 (Ballymun), 10 (Ballymount), and 12 (Firhouse). The remaining junctions, 11 (Tallaght/N81), and 14 (Sandyford), which were of the roundabout type, had one or two left-turn slips added, these junctions not previously being noted for excessive traffic congestion anyway.

The only junction within the scope of the upgrade that got off scot-free was 13 (Ballinteer). This junction had only opened in 2001 and had been constructed to a high standard in the first place.

On 1st September 2010, construction wrapped up on the M50 rebuild. It had taken over four years and costs €950M, caused years-long traffic snarl-ups; and inspired the nation. The country's capital finally had a ring road system to be proud of.

Of course the other main omission in the upgrade project was Junctions 14-17, the south-eastern section that had opened in 2005. Due to lower traffic levels here, and lack of significant development along the segment's path, widening to 6 lanes or junction improvements were not considered to be warranted at that time. However, in Autumn 2015, it was announced that widening of that section would go ahead before 2035. This is to make a uniform standard for the whole M50 and to serve newly-developing areas such as Cherrywood.

In the future, if the Eastern Bypass is ever built, there will be another motorway coming south and joining the M50 at the Sandyford exit, or possibly further south where there is more room. This road would also be designated the M50, at which point the stretch from junctions 14-17 would become M11 to link in with the rest of the M11 to the south.

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Wikipedia page on this road

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Traffic Counts for this road


Origin East Wall Rd, Dublin Port
Terminates M11 Shankill, south of Dublin
Places Served Dublin Port, Coolock, Dublin Airport, Ballymun, Finglas, Blanchardstown, Mulhuddart, Palmerstown, Lucan, Clondalkin, Ballymount, Cookstown, Tallaght, Templeogue, Ballinteer, Sandyford, Leopardstown, Carrickmines, Cherrywood, Shankill
Routes Spawned N7/M7
Intersects M1, N2, N3, N4, M11, N31, N81


Section km Opening Date Standard
Jct 6-7 N3-N4 3.2 1990-03
Jct 7-9 N4-N7 4.6 1990-05-02
Jct 9-11 N7-N81 4 1990-12-17
Jct 3-6 M1-N3 11 1996-12
Left turn slips to several junctions 2001 INTERCHANGE UPGRADES
Jct 11-13 N81-Ballinteer 9 2001-07-31
Jct 13-17 Ballinteer-M11 11.4 2005-06-30
Jct 15 Carrickmines 2005-10 INTERCHANGE
Jct 1-2 Dublin Port Tunnel 6 2006-12-20
Jct 7-10 Upgrade (Phases 1 and 3) (9.7) 2008-12 INTERCHANGES AND WIDENING
Jct 3-6 and 11-14 Upgrade (Phase 2) (24) 2010-09-01 INTERCHANGES AND WIDENING
Jct 14-17 Widening (7.8) 2035 WIDENING
Jct 1-? Port Tunnel-South Port 1.7 2035