Dublin’s Road Network and traffic lights: A Recipe for Traffic Congestion and Inefficiency

Wed 16 Oct - Adam Ross - Transport Planner at Metro Dublin

Dublin, Ireland’s bustling capital, is home to over a million residents, a growing number of businesses, and countless tourists. However, despite its increasing population and economic importance, Dublin’s road infrastructure has lagged far behind the demands of a modern city. The city's road network is plagued with inefficiencies, poor capacity, and unreliable traffic management systems, all of which have a serious impact on public transport services.

Narrow Roads: No Room for Bus Lanes
One of the most significant issues with Dublin’s road network is its narrow streets. Many of the city's main roads are only two lanes wide, leaving no space for dedicated bus lanes or cyclist infrastructure. This not only limits the flow of general traffic but also hinders the ability of buses to bypass congestion. During peak hours, buses share the same gridlock as private vehicles, which contributes to slow, unpredictable public transport times. The absence of bus lanes on many arterial roads, such as Rathfarnham Road and Terenure Road South (two massive choke points for congestion), leaves bus services at the mercy of daily traffic jams, severely undermining their reliability. While Busconnects aims to create more dedicated bus corridors on various roads in the city, this will lead to the demolition of many gardens and vegetation which the public are not happy about.

Dublin's road network bird's eye (notice the bendy and inefficient design)

In many European cities, networks of dedicated bus lanes allow for smoother, faster bus transit even during rush hour. Dublin, by contrast, has largely failed to provide this infrastructure. As a result, buses are not only slow but often overcrowded, as they’re forced to contend with the same inefficiencies that plague private car journeys.

Windy, Narrow, and Overcrowded Roads
In addition to being narrow, many of Dublin’s roads are also winding and poorly designed for high traffic volumes. The street layout reflects a legacy of historic development, where roads were originally built to serve small, local communities. As Dublin’s population has expanded, these same roads have been pressed into service for much larger volumes of traffic without substantial upgrades.

For example, routes like the where the 15B bus goes are not only narrow but also feature numerous bends, curves and intersections making it difficult for buses to maintain consistent speeds and stopping every few hundred metres to load and unload passengers doesn’t help. These roads often feel outdated for a city of Dublin’s size, contributing to traffic that is frustratingly stop-and-go. Without proper alternatives, these roads are continually jammed with commuters, further exacerbating delays.

Dublin Bus route 15B section must curve and bend alot to reach key areas

Dublin's Poorly Timed Traffic Lights
The problem isn’t just the roads themselves. Traffic signal management in Dublin is often inefficient and poorly synchronized, contributing significantly to the city's congestion woes. Large intersections, such as the one at O'Connell Bridge, at Heuston Station, or around Terenure are prime examples where traffic lights are poorly timed. Traffic signals don’t appear to be optimized for real-time traffic flow or peak congestion, resulting in long waits at red lights even when there’s little cross-traffic.

In many cases, these traffic signals work against efficient movement rather than supporting it. At large junctions, the lack of synchronization between sets of lights means that vehicles are often stopped in queues only to encounter another red light moments later. These inefficiencies have a ripple effect throughout the road network, leading to significant backlogs of traffic even at non-peak times. In smaller junctions, where lights are placed too close together, this poorly timed coordination causes queues to stretch far beyond the junction itself, creating bottlenecks that should be avoidable.

​This mismanagement directly affects bus services as well, which must adhere to timetables that are often impossible to keep due to these unpredictable and inefficient signal patterns. During peak hours, the delays can add up to 30 minutes or more to an already long journey, making public transport a less attractive option for Dubliners who could otherwise be using more efficient systems.

Multiple junctions close together in Terenure which are prone to congestion

Huge junction near Tallaght is prone to congestion and poor timing for optimal traffic flow

Potential Solutions to Dublin's Traffic Light Timing
​Dublin’s traffic lights could be significantly improved by implementing smart traffic management technologies that prioritize efficiency and public transport. Using real-time sensors to detect traffic volumes at different intersections, the lights could dynamically adjust to reduce congestion in heavily trafficked areas. Additionally, introducing bus priority signals—where traffic lights change to green when buses approach—would help public transport bypass traffic and stay on schedule. These improvements would streamline traffic flow, reduce delays, and enhance the overall efficiency of Dublin’s road network.

Overcrowded and Unreliable Bus Services
Given these infrastructure challenges, it’s no surprise that Dublin’s bus services suffer from chronic overcrowding and unreliable timetables. The lack of bus lanes means buses are often caught in the same congestion as private vehicles, while narrow roads and close-proximity junctions create frequent bottlenecks that slow traffic to a crawl. This results in buses being packed during rush hours, with commuters having to stand in uncomfortable conditions while journeys take far longer than they should.
This congestion and delay also affect the reliability of Dublin's public transport. With buses arriving late or in bunches, Dublin Bus struggles to maintain consistent service, making it harder for commuters to rely on the system. Overcrowding further compounds the issue, as passengers are sometimes left stranded when full buses cannot accommodate them.
These problems discourage people from using public transport and force more people to drive, worsening the congestion issue in a vicious cycle.

The Case for Metro Dublin
In this context, Dublin’s dire need for Metro Dublin becomes all the more apparent. Metro Dublin will offer a fast, reliable, efficient short to medium term alternative to the city's increasingly overwhelmed bus services. Unlike buses, Metro Dublin will operate on dedicated underground lines, entirely separate from surface traffic. This would allow Dubliners to bypass the clogged roads altogether, ensuring faster and more predictable journey times.
Metro Dublin will also reduce the strain on the city’s road network by encouraging more people to switch from cars to public transport. With fewer cars on the road, there would be less congestion, creating a positive feedback loop for the city’s transport system. Cities like Madrid, Paris, and even smaller European capitals such as Oslo have long since realized the benefits of metro systems, which help manage high volumes of passengers efficiently while freeing up road space for other uses.

Furthermore, Metro Dublin will greatly complement Dublin’s existing but struggling transport infrastructure, integrating with buses, trams (Luas), and commuter services (DART). This would create a cohesive, multimodal network that gives commuters more options and flexibility.

Metro Dublin 2032 Map

​Dublin’s road network is a serious impediment to the city’s efficiency and growth. Narrow, winding roads, poorly timed traffic lights, and a lack of bus lanes all contribute to a congested, slow-moving system that fails to meet the needs of its citizens. Public transport, particularly the bus network, suffers as a result, leading to crowded, unreliable services that are unable to cope with demand. Metro Dublin will help alleviate many of these issues, providing a faster, more reliable, and sustainable solution to the city’s transport woes.

Without significant investment in both road and public transport infrastructure, Dublin will continue to struggle with congestion and inefficiency, limiting its potential as a modern European capital. A metro system is not just an option for the future—it is an urgent necessity.