- BY Kevin Barry BSc(Hons) MRICS
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What Would a Proper Business Case for the Strangford Lough Crossing Actually Show?
There is a question that keeps being asked in response to this campaign, often by people who mean well. It goes something like this: “But surely the numbers just do not stack up for a bridge over Strangford Lough?”
It is a reasonable thing to wonder. And the honest answer is that nobody actually knows, because nobody has been asked to find out. The Department for Infrastructure has declined to commission a feasibility study. What it has done instead is produce an internal back-of-envelope estimate, described by its own author as a “guesstimate,” and use that figure to close down the conversation.
So let us do what DfI has declined to do. Let us run the numbers. Hypothetically, if an independent economist were appointed by the Minister to conduct an Outline Business Case under the Department of Finance’s Better Business Cases NI Five Case Model — the standard Green Book framework applied to all major public spending proposals in Northern Ireland — what would it find? Here is the honest answer, built from documented sources.
The Strategic Case
The strategic case is the foundation. It asks a simple question: is there a compelling case for change?
The ferry currently carries approximately 650 vehicles per day. It operates at 34% of its theoretical capacity. Research published by this campaign shows that 83% of potential users avoid the service entirely, using the 75-kilometre road detour instead or simply not making the journey at all. Of 458 respondents to the 2024 community survey, 94% described the service as not fit for purpose. In 2023/24 alone, 848 sailings were cancelled — due to fog, mechanical failure, staff shortages, and industrial action.
The financial picture is equally stark. The ferry costs £3.52 million per year to operate. Fare income covers just £1.43 million of that. The net annual subsidy to the taxpayer is £2.09 million. That subsidy has existed since Roads Service assumed responsibility for the crossing in 1973 — over fifty years. On current trajectory, with the operating deficit growing at 4.8% per year, that annual bill will reach £8.51 million by 2054.
The Ards Peninsula, which the ferry is meant to serve, has the lowest median weekly wages in Northern Ireland at £450.10, according to the Sub-Regional Economic Plan Technical Annex published by the Department for the Economy in October 2024. The connectivity deficit is not incidental to that economic underperformance. It is structural.
The strategic case writes itself.
The Economic Case
The economic case is where the real work lies, and where the most important numbers sit.
The Green Book requires a cost-benefit analysis across the full asset lifetime. For a bridge, that means 60 years at minimum — bridges routinely last a century or more. The comparison is not simply between building a bridge and doing nothing. It is between three options: doing nothing and absorbing an escalating subsidy in perpetuity; investing in an electrified ferry replacement; or building a permanent fixed crossing with tolling.
Do Nothing
Continuing the current service means accepting a certain and escalating liability. The 60-year present value of the ferry operating subsidy, discounted at 3.5% under Green Book methodology, is £95-125 million — with no economic return whatsoever. There is no Benefit-Cost Ratio to calculate. There are only costs, compounding year on year, with the service deteriorating as the vessels age and the deficit widens.
Do Minimum: Electrified Ferry
The electrified ferry option fails first and fails badly. An independent analysis prepared for this campaign in January 2026, drawing on the HITRANS Corran Fixed Link Feasibility Study (Stantec UK/COWI, 2020) and DfI’s own FOI-released financial data, calculates its Benefit-Cost Ratio as follows.
Net 60-year cost (present value, after fare revenue): £80 million. Monetised economic benefits over the same period: £10-20 million — modest environmental gains from reduced diesel consumption, and nothing else of substance. Journey times are unchanged. Operating hours are unchanged. Weather reliability is unchanged. Capacity constraints are unchanged. The service continues to suppress the demand that a fixed crossing would release.
Electrified Ferry BCR: 0.1-0.25:1. Green Book threshold: 1.0. It fails.
This matters because it exposes the false choice DfI implicitly presents. The ferry is not the cheap option. It is the option that costs £80 million in present value terms and returns nothing of economic consequence. It is the option that perpetuates regional inequality, suppresses connectivity, and commits the public purse to an escalating subsidy with no end date.
Preferred Option: £300 Million Fixed Crossing with Tolling
The bridge is assessed over a 60-year appraisal period, applying the standard WebTAG discount rates of 3.5% for the first 30 years and 3.0% thereafter. Gross present value cost is £327 million. Against that, three BCR scenarios have been modelled, each representing a different level of traffic demand release and funding structure.
Pessimistic Scenario: High Construction Cost, Low Traffic Demand
This scenario assumes construction costs at the upper end of the risk-adjusted range and traffic growth at its most conservative — just 50% above current suppressed ferry volumes, with no compound growth assumed over 60 years. Net bridge cost after toll revenue: £305 million present value. Total economic benefits: £626 million present value, incorporating transport economic efficiency gains, partial wider economic impacts, and healthcare system savings.
Pessimistic BCR: 2.1:1. WebTAG classification: High Value for Money.
Even under the most unfavourable assumptions this campaign is prepared to apply, the bridge clears the Green Book threshold by more than double.
Conservative Base Case: 15% of Cleddau Bridge Growth Trajectory
This scenario assumes Strangford achieves just 15% of the traffic growth trajectory demonstrated by the Cleddau Bridge in Wales over 49 years — a deeply conservative assumption given that Strangford serves a larger population catchment with stronger economic drivers. Year 1 traffic on opening: 886,000 crossings annually (2,428 per day). Net bridge cost after toll revenue over 60 years: £209 million present value. Total economic benefits: £894 million present value.
Conservative BCR: 4.3:1. WebTAG classification: Very High Value for Money.
Moderate Base Case: 30% of Cleddau Bridge Growth Trajectory
This scenario assumes Strangford achieves 30% of the Cleddau growth trajectory — still a fraction of what comparable fixed links have demonstrated. Year 1 traffic: 1,064,000 crossings (2,915 per day). Net bridge cost after toll revenue: £158 million present value. Total economic benefits: £1.332 billion present value.
Moderate BCR: 8.4:1. WebTAG classification: Very High Value for Money.
The critical comparison point is the Cleddau Bridge itself. When Wales built their permanent crossing in 1975, the ferry they had been operating was transferred to Strangford — it became our MV Portaferry. In its first year of operation, the Cleddau Bridge carried 885,900 vehicles: 2,428 per day. Today it carries 4,745,000 vehicles per year — approximately 13,000 per day. That is a 20-fold increase over 49 years from a comparable suppressed-demand starting point. Strangford’s ferry, over the same period, has remained essentially static.
The BCR summary, set against the Green Book threshold, is as follows.
| Option | Net Cost (PV) | Benefits (PV) | BCR | WebTAG Classification |
|---|---|---|---|---|
| Do Nothing | £95-125m subsidy | Nil | N/A | Not applicable |
| Electrified Ferry | £80m | £10-20m | 0.1-0.25:1 | Below threshold — not justified |
| Bridge — Pessimistic | £305m | £626m | 2.1:1 | High Value for Money |
| Bridge — Conservative | £209m | £894m | 4.3:1 | Very High Value for Money |
| Bridge — Moderate | £158m | £1,332m | 8.4:1 | Very High Value for Money |
Every bridge scenario clears the Green Book threshold. The electrified ferry does not clear it in any scenario. The Do Nothing option does not even have a ratio to calculate — it is pure cost with no return.
The Financial Case: Three Funding Scenarios
This is where the funding question becomes concrete. Three realistic funding structures have been modelled, all targeting a 25-year payback on the capital recovered through tolling, with a blended average toll of £3.50 per crossing — set at 50% of the current ferry single fare of £7.70, consistent with the approach recommended in the HITRANS Skye Bridge analysis. Annual bridge maintenance is costed at £1.50 million per year (0.5% of capital), and toll collection efficiency is assumed at 95% using an ANPR-based system modelled on the Mersey Gateway Bridge.
Scenario A: 50% UK / 50% Irish Shared Island Initiative Grant Funding
The Irish Government’s Shared Island Fund holds €2 billion through 2035, confirmed in the NDP Sectoral Plan: Shared Island (July 2025). The Irish Government has confirmed in principle its openness to Strangford Lough Crossing co-funding (DOT-TM25-11858-2025). The UK Government holds direct infrastructure spending powers under section 50 of the UK Internal Market Act 2020. The Narrow Water Bridge — €102 million, currently on programme — was funded entirely through the Shared Island Fund and provides the direct precedent.
Under this scenario, each jurisdiction contributes £150 million, covering the full £300 million gross capital cost. No toll revenue is required for capital recovery. Tolling need only cover annual maintenance of £1.50 million. At £3.50 blended average and 95% collection efficiency, that requires 1,311 vehicles per day — twice the current suppressed ferry volume, and below the 2,428 that the Cleddau Bridge achieved on its very first day of operation in 1975. The bridge is self-sustaining from opening day. Under the conservative BCR scenario (4.3:1), the economic return on the combined £300 million public investment is £894 million — nearly three pounds returned for every one invested before tolling revenue is even considered.
Scenario B: 30% UK / 30% Irish Shared Island Initiative Grant Funding
Here each jurisdiction contributes £90 million, totalling £180 million in grant funding. The residual £120 million is recovered through tolling over 25 years. Annual toll revenue required is £6.30 million, demanding 5,192 vehicles per day. That is consistent with traffic volumes the Cleddau Bridge achieved between Years 20 and 25 of operation — a reasonable expectation for a crossing serving a larger and more economically dynamic catchment. The BCR of 4.3:1 (conservative) applies to the full scheme regardless of funding split; the distinction here is that £120 million of the public investment is recovered through user charges rather than retained as a grant contribution.
Scenario C: 40% Toll Recovery / 60% Public Funding
In this scenario, tolling recovers 40% of the gross capital — £120 million over 25 years. The remaining £180 million is funded publicly, split indicatively as £90 million from each jurisdiction. The tolling requirement is identical to Scenario B at 5,192 vehicles per day, because the toll recovery target is the same. The distinction from Scenario B is structural rather than operational: the public funding is framed as a defined capital contribution rather than a grant, giving both governments a clearer accounting basis for the investment. The BCR of 4.3:1 (conservative) is unchanged — the economic return is a function of the scheme, not of how it is financed.
The Three Scenarios Compared
| Scenario A | Scenario B | Scenario C | |
|---|---|---|---|
| Grant / public funding | £300m | £180m | £180m |
| Toll recovery target | Nil | £120m | £120m |
| Annual toll revenue required | £1.50m | £6.30m | £6.30m |
| Daily crossings required | 1,311 | 5,192 | 5,192 |
| Multiple of current ferry | 2.0x | 7.99x | 7.99x |
| Cleddau comparator | Below Year 1 | Years 20-25 | Years 20-25 |
| Payback | Day 1 | Year 25 | Year 25 |
| BCR (conservative) | 4.3:1 | 4.3:1 | 4.3:1 |
| BCR (pessimistic) | 2.1:1 | 2.1:1 | 2.1:1 |
| WebTAG classification | Very High VfM | Very High VfM | Very High VfM |
| DfI’s own payback figure | 356 years | 356 years | 356 years |
| Reduction vs DfI figure | 356 years | 331 years | 331 years |
It is worth pausing on that last row. DfI’s own internal calculation, prepared in August 2024 (FOI DFI-2024-0412), concluded that payback would take 356 years. That calculation used only the current suppressed ferry volume of 650 vehicles per day at £7.70 per crossing, with no tolling model and no induced demand. It is, in the words of its own author, a guesstimate. Scenario A reduces that figure to zero on day of opening. Even Scenarios B and C reduce it by 331 years.
The Commercial and Management Cases
The contractor who built the Rose Fitzgerald Kennedy Bridge — 887 metres, delivered on programme in 2020 — is currently on site delivering the Narrow Water Bridge to schedule and within its €102 million budget. The market is proven. The technology is proven. The governance model is proven, with the Narrow Water Bridge Oversight Board providing a directly transferable template.
A bridge at Strangford would require a Bridge Order, an Environmental Impact Assessment for the Special Area of Conservation and Area of Special Scientific Interest designations, and geotechnical investigation at OBC stage to confirm ground conditions at the proposed crossing point. None of these are insurmountable. They are standard steps in a standard process.
The Conclusion an Independent Business Case Would Reach
Across all five cases — Strategic, Economic, Commercial, Financial and Management — the evidence converges on a single finding. The Strangford Lough Crossing is not a fantasy. It is not unaffordable. It is not economically unjustifiable. It clears every Green Book threshold, in every scenario, at every level of funding ambition from the most conservative to the most optimistic.
The BCR range of 2.1:1 to 8.4:1 across all bridge scenarios compares favourably with the majority of DfI-approved infrastructure schemes. The electrified ferry — the implicit default if the bridge is not built — fails that same test at 0.1-0.25:1 and should not be presented as a credible alternative.
The only thing the crossing does not yet have is the independent, formally commissioned feasibility study that would convert this analysis from a campaign document into a departmentally owned, ministerially accountable assessment.
That study costs £150,000. Four weeks of the current ferry subsidy. Less than a single week of the subsidy that will be paid out annually by 2054 if nothing changes.
DfI has been asked to commission it. It has declined. The Minister has said, on the record in the Assembly on 3 February 2026: “why not? I am happy to keep that under review.” That question — why not? — remains unanswered.
We are not asking for a bridge. We are not getting ahead of ourselves. To date, we have gone further than the past 20 years of effort. We are asking for an honest answer.
Kevin Barry BSc(Hons) MRICS is a Chartered Quantity Surveyor based in Portaferry and Campaign Lead for the Strangford Lough Crossing Campaign. All figures derived from documented sources including FOI disclosures DFI-2024-0366 and DFI-2024-0412; HITRANS Corran Fixed Link Feasibility Study (Stantec UK/COWI, 2020); NDP Sectoral Plan: Shared Island (July 2025); Sub-Regional Economic Plan Technical Annex (Department for the Economy, October 2024); and Cost and TAG Compliance Analysis — Electrified Ferry Service vs £300 Million Bridge with Tolling (Kevin Barry BSc(Hons) MRICS, January 2026). Further information at www.strangfordloughcrossing.org