Analysis 2 asks not which lines to reopen but how fast trains should run. The short answer, from the All-Island Strategic Rail Review: 200 km/h is the economic ceiling — faster does not pay.
Today's speeds
Dublin–Cork is the fastest line, and the only one cleared for the top speed. The island's maximum is 160 km/h (100 mph) on Dublin–Cork and 145 km/h (90 mph) in Northern Ireland. What passengers feel is the average city-to-city speed, far lower because of stops, curves and single track (rounded, so indicative):
| Route | Rail distance | Fastest time | Average speed |
|---|---|---|---|
| Dublin–Cork | ~266 km | ~2h 30 | ~105 km/h |
| Dublin–Belfast | 181 km | ~2h 05 | ~85 km/h |
| Dublin–Limerick | ~200 km | ~2h 10 | ~90 km/h |
| Dublin–Galway | ~210 km | ~2h 30 | ~84 km/h |
| Dublin–Sligo | ~215 km | ~3h 00 | ~72 km/h |
| Dublin–Waterford | ~160 km | ~2h 15 | ~71 km/h |
Why 200 km/h is the ceiling
To average 120 km/h — fast enough to beat the car once stops are allowed for — trains need to run at up to 200 km/h. That is the Review's target. Above it, the only way to go faster is a dedicated, segregated high-speed line, which the Review assessed as a 300 km/h network and rejected: the benefits would be significantly outweighed by the costs,
with diminishing economic returns in targeting speeds above 200km/h
and construction carbon that would not be offset.
What speed costs
Tier A — lift the slow network
Curve easing, track and signalling on existing alignments to the Review's “at least 120 km/h” minimum, largely within ongoing renewals.
Tier B — a 200 km/h electrified railway
New trains plus signalling, track, level-crossing and electrification upgrades. The recommended tier. Whole programme: €32bn (2021) / €35–37bn (2023), about €1.3bn a year for ~25 years.
Tier C — 250–300 km/h high-speed
A new segregated alignment end-to-end. Rejected on cost, carbon and value-for-money grounds.
Express running & the cost of overtaking
The cheapest speed gain is not a faster train but a train that stops less. A Dublin–Cork express that skips stops saves minutes per stop. The catch: on two tracks it soon catches the stopper ahead, so express running only works if the fast train can overtake — which needs extra track, either four-tracking at the pinch points or shorter passing loops.
The pinch-points sit at the busy Dublin approaches, where intercity expresses share tracks with Dublin Area Rapid Transit (DART) and commuter stoppers. Four-tracking there lets the fast trains pass. Costs (from the Review's table, 2021 prices):
| Work | Cost |
|---|---|
| Dublin–Cork speed improvements | €500–800m |
| Four-track: Dublin–Clongriffin | €700m–€1.0bn |
| Four-track: Clongriffin–Drogheda | €600m–€1.0bn |
| Four-track: Hazelhatch–Portarlington | €1.1–1.8bn |
| Four-track: Belfast–Newry | €1.8–2.8bn |
Four-tracking is a joint product — the same tracks serve frequency, capacity and express overtaking — so its cost is justified by growth, not charged to express alone. The Review calls four-tracking the Dublin approaches essential to enable the intercity network to grow.
What speed, on what routes
Build to 200 km/h on the two corridors that can fill it — Dublin–Cork and Dublin–Belfast — lift everything else to a 120 km/h floor, and build nothing for 300 km/h.
| Corridor | Target | Tier | Why |
|---|---|---|---|
| Dublin–Cork | 200 km/h | B | Straightest, busiest; the prime 200 candidate, with demand to fill it |
| Dublin–Belfast | 200 km/h | B | Flagship corridor; new fleet + four-tracking; sub-2-hour target |
| Limerick / Galway / Waterford | 120→160, 200 selectively | A→B | Mixed alignment; hit the floor, raise straight sections where it pays |
| Western & border lines | at least 120 km/h | A | Thin, winding, low-demand; raise the floor through renewals |
| Any corridor at 250–300 km/h | none | C | Rejected island-wide: diminishing returns, carbon, value for money |
The two 200 km/h corridors are firm; the middle rows apply the Review's logic (it commits to a 200 km/h core and a 120 km/h minimum but publishes no line-by-line speed table). Route averages above are computed from rounded distances and times.
Visualise the trade-off
The two curves below are the Review's conclusion in one picture: the benefit of going faster rises steeply at first, then flattens once rail beats the car around 200 km/h, while the cost stays modest up to 200 km/h and then climbs steeply for a segregated high-speed line.
● Benefit (time saved, modal shift) ● Capital cost — schematic of the Review's qualitative finding; beyond 200 km/h only a segregated line can go faster, at a far higher cost.
Test a corridor at different top speeds
Pick a route and drag the top speed. The journey time and the “beats the car” test improve with speed, but the tier badge shows the catch: above 200 km/h the only way faster is a segregated line the Review rejected.
The interactive speed explorer is on the live page at trainproject.org/speed.html
References
- All-Island Strategic Rail Review, Department of Transport / gov.ie, 2024 — speed targets, costs (incl. the four-tracking table), the 300 km/h rejection.
- Mark 4 (Iarnród Éireann), Wikipedia — 160 km/h operating, 200 km/h design.
- Enterprise (train service), Wikipedia — Dublin–Belfast times and the new fleet.
- Transport Appraisal Framework, gov.ie — discount rate and value of time behind the valuation.