Four in five Northern Ireland buses still run on diesel as rural fleet ages past ten years
Official fleet statistics reveal that 80.2% of Translink buses were diesel-powered and Ulsterbus vehicles averaged 10.7 years old, versus 7.1 for Metro.
Northern Ireland's bus fleet remains overwhelmingly diesel-powered, while the vehicles used by Ulsterbus are on average 3.6 years older than those in the Belfast Metro fleet. New analysis of official transport figures brings the difference into focus as government plans increasingly rely on public transport to carry more journeys.
At the end of March 2026, Translink operated 1,416 buses. Of those, 80.2% were diesel vehicles, 17.4% were classified as zero-emission and 2.4% were diesel hybrids, according to accredited statistics produced for the Department for Infrastructure.
The report also gives three sharply different average fleet ages. Ulsterbus vehicles averaged 10.7 years old, Metro buses 7.1 years and Gliders 7.5 years. The published data do not specify the average age of diesel and zero-emission vehicles separately, or establish that every Ulsterbus vehicle is diesel. What they do establish is that the fleet supporting journeys across Northern Ireland is older on average than the buses serving Belfast's urban network.
The rural and urban divide in numbers
Ulsterbus accounted for 1,078 of the 1,416 vehicles in operation, approximately 76% of the total. Metro had 304 and Glider 34.
That distribution matters because a change in the Ulsterbus fleet has a large impact on the age and composition of Northern Ireland's buses overall. Replacing a handful of city vehicles does not transform the condition or average age of a network in which more than three-quarters of buses carry the Ulsterbus designation.
The 3.6-year gap between the mean ages of Ulsterbus and Metro vehicles is an average, not a measure of whether a particular bus is safe or reliable. A well-maintained older bus may remain fit for service; a much newer vehicle can still suffer breakdowns.
But age has implications for maintenance planning, parts replacement, accessibility upgrades and the timetable for introducing different propulsion technologies. Those factors matter to the public because buses are a visible part of the transport system, not just an accounting category.
The annual report does not supply enough information to determine whether the age gap has caused a higher rate of service cancellations or defects. Any such assertion would need separate operational data.
Zero-emission progress does not mean the diesel fleet has disappeared
The 17.4% zero-emission share represents genuine deployment of cleaner vehicles. It is nonetheless far below half of the operational fleet.
At the other end, diesel vehicles still made up just over four in every five buses. Diesel hybrids accounted for a further 2.4%; these should not be added to zero-emission vehicles, because their classification is different.
The statistics provide an end-of-March snapshot, not a statement that the fleet has remained unchanged every day since. Fleet orders, new vehicle deliveries and withdrawals may have occurred later in 2026.
The crucial unanswered question is where the zero-emission vehicles operate. A fleet-wide percentage cannot demonstrate how evenly the benefits of new technology are distributed between metropolitan routes and smaller communities. That would require a breakdown by operating network and depot, which is not included in the headline figures.
For a driver considering leaving the car at home, the existence of a cleaner bus is only one part of the decision. Frequency, journey time, cost, reliability and the availability of a service near home are likely to matter just as much.
Bus journeys are still barely above last year's level
The annual passenger figures add a second dimension. Bus patronage reached 68.1 million journeys in 2025/26, an increase of 0.3 million — or 0.5% — compared with the previous year.
Rail journeys grew much faster, up 19.2% to 15.9 million. Total public-transport journeys reached 84.0 million, up 3.6%. PureCar has already reported the difference in passenger growth, but the fleet figures show that the challenge for buses is not just how many people travel: it is what vehicles support those journeys and how investment is distributed.
Bus and rail journeys are not interchangeable measures of vehicle use. A passenger's commute involving two bus services may involve multiple boardings, and the statistics do not show the number of unique people choosing public transport instead of a private car.
The point is that improvements to the fleet need to be judged alongside the service passengers actually receive.
Why the replacement timetable matters
Northern Ireland's wider transport strategy places emphasis on reducing emissions and offering alternatives to private-car travel. The official statistics identify domestic transport as a major source of greenhouse-gas emissions, accounting for 21.3% of the region's total in 2024.
It would be wrong to assign that 21.3% to buses. It refers to domestic transport as a whole, including private vehicles and other modes.
The bus fleet is nevertheless part of the sector's transition. A programme of zero-emission vehicle replacement can reduce emissions from the services using those vehicles, but the pace and geography of the investment determine how quickly the benefits can spread.
A full assessment should also account for the electricity source, vehicle manufacture and maintenance requirements, rather than comparing exhaust emissions alone.
The evidence the next fleet report should publish
The official return makes two points clear: diesel remains dominant and Ulsterbus has a substantially older average fleet than Metro.
To assess what comes next, readers need more detail than a single fleet-wide percentage. How many zero-emission buses are in each service category? What are the planned replacement dates for the oldest vehicles? How many miles do those vehicles cover annually? And will more rural routes receive newer buses, or will investment remain concentrated on the corridors where electrification is easiest?
The current figures cannot answer those questions. But they provide a measurable benchmark against which future announcements can be tested.
Northern Ireland has 1,416 operational buses in the latest complete annual snapshot. More than 80% are diesel, and the largest component of the network has an average age exceeding ten years. The next major development is not simply the unveiling of another new bus. It is whether the composition of the entire fleet begins to change.
