Meter the tunnel before you promise the motorway's carbon

A motorway operator's carbon footprint is dominated by something it does not control. The fuel burned by the vehicles on our roads produces emissions many times larger than anything Elvaran does directly. It is tempting, and sometimes encouraged, to put that enormous figure at the centre of a sustainability story: to model it, to announce ambitions about it and to report progress against it. I think that is the wrong place for an infrastructure operator to start, and that the credibility of our reporting rests on a much duller foundation.

My argument is that an operator should first measure its own energy use properly, at the level of the asset, before it publishes ambitions about the far larger and more uncertain emissions of its users; and that measured and modelled figures should be reported separately and never blended into a single goal.

The pressure to report has grown. Elvaran published its first sustainability statement under the EU's new reporting standards in 2025, covering 2024, with limited assurance from our auditors. The regime asks companies to explain what is material to them and to support their disclosures with data that can be assured. The debate during 2025 about simplifying the rules did not change our position: the data either supports the statement or it does not.

What the meters showed

Before 2023 we knew our electricity consumption from supplier invoices, one per connection point. A single invoice could cover a tunnel's ventilation, lighting, pumps and control room, plus a nearby maintenance depot. We could report a total with confidence and explain almost nothing about it.

Between 2023 and 2025 my function installed 1,860 sub-meters across our 14 tunnels, our toll plazas and maintenance centres and the common parts of our 22 service areas, and connected them to the operational data platform. The programme cost €3.4 million. Most of its value came from what we learned in the first year.

Tunnel lighting and ventilation together accounted for about 58 per cent of our electricity. In two tunnels on the northern concession, ventilation fans were running in a test mode for several hours each night, a configuration left over from commissioning that nobody had reversed. Correcting it saved about 1.9 gigawatt-hours a year. Several toll plazas replaced by free-flow gantries were still heating and lighting buildings nobody used. And the entrance-zone lighting in four tunnels, which is adjusted to the brightness outside the portal, was set more conservatively than the design required.

None of these findings needed new technology. They needed someone to look at a number broken down finely enough to provoke a question. Those corrections, together with the conversion of tunnel lighting to LED, cut our electricity consumption by 17 per cent between 2022 and 2025 while traffic grew.

The meters also changed who felt responsible. Before 2023, electricity was a line in the finance team's cost report and nobody in operations was asked to explain it. Now each tunnel manager receives a monthly breakdown of ventilation, lighting and pumping against the previous year, with any meter that has stopped reporting listed at the top. The first few months produced defensive conversations. Within a year the tunnel managers were bringing anomalies to us, including a pump cycling every few minutes because of a failed level sensor, which no invoice would ever have revealed.

The data had a further use I had not anticipated. When our auditors began their limited-assurance work, the first questions concerned completeness: how did we know every connection point was included, and what happened when a reading was missing? A register of meters, each linked to an asset and a supply point, answered both. Without it we would have been reconciling invoices by hand and explaining estimates line by line.

Two kinds of number

The emissions of the vehicles on our roads are a different kind of figure. We estimate them from traffic counts at our toll points, assumptions about the mix of vehicles and their emission factors, and average trip lengths. Those estimates are useful. They inform discussions with grantors about charging infrastructure for heavy vehicles, and they show the scale of the transition the road network is part of. But they are modelled from assumptions, many of which we cannot verify, and they move with fleet renewal, fuel prices and the economy, none of which our decisions control.

When a report adds measured electricity to modelled traffic emissions and presents a total, the reader cannot tell which part is evidence and which part is estimate, and a small change in a traffic assumption can swamp a real improvement in our own operations. I have argued, successfully so far, that Elvaran should present the two in different sections with different explanations of method and uncertainty, and that the board should see them the same way.

This is partly about assurance. Our auditors can test the controls around a meter reading: the device, its calibration, the data flow, the handling of a meter that stops reporting. With a traffic model they can test the arithmetic, but not the world it describes. A board that understands which of its sustainability figures rest on which kind of evidence is better placed to approve the statement.

Targets we can be held to

The same distinction should shape targets. Elvaran's commitments for 2030 cover the energy and emissions we control: our buildings, tunnels, lighting, vehicle fleet and the electricity we buy. I am comfortable being held to those. For the emissions of road users, we describe the actions we will take, such as charging capacity at service areas and traffic data shared with grantors and fleet operators, rather than promising a reduction that depends on millions of other people's choices of vehicle.

Some colleagues think this is unambitious and that investors expect a headline figure for the whole value chain. I understand the argument. But an ambition that cannot be measured with the same quality as our own consumption invites the accusation that it was chosen for its size. I would rather report a smaller number we can defend, explain the larger one carefully and let the reader judge.

There is a practical lesson for any operator starting this work. Buy the meters before the consultants. The first year of granular data will tell you more about your own operations than any model, and it will give your reporting a foundation that survives a sceptical auditor and a sceptical reader. The traffic estimate can come later, clearly labelled, as context rather than as a claim.