Our impact

Lighting the Limerick Tunnel

Reducing cost and adding value

An innovative system of lighting control has been installed in the Limerick Tunnel and on its approach roads, after a process of analysis by DirectRoute supported additional investment in greater energy efficiency.

Total saving of

€ 120,000

Electricity savings of

18%

Lights in the tunnel

1,560

Sound financial management of large infrastructure assets demands periodic review to find ways of reducing cost and adding value, which is exactly what has been done in Limerick in the Irish Republic. An innovative system of lighting control has been installed in the Limerick Tunnel and on its approach roads, after a process of analysis by DirectRoute supported additional investment in greater energy efficiency.

Meridiam helped to bring about construction of the Limerick Tunnel and it continues to maintain the safe and serviceable operation of this important asset, as a lead partner in DirectRoute. This is the special purpose vehicle that holds a 35 year concession to design, build, finance and operate the tunnel and its approach roads for the Irish government agency Transport Infrastructure Ireland (TII). Meridiam’s direct interest has led it to take an active role in ensuring the Limerick Tunnel is operated diligently and to make sure every effort is made to add value for the partners and investors of DirectRoute and TII.

There are 1,560 lights in the Limerick Tunnel and 763 on its approach roads.

Just a year after its opening, DirectRoute took a long hard look at the lighting of the tunnel and connecting roads. Electricity bills represent a large proportion of the cost of operating highway assets – particularly so in the case of a road tunnel. There are 1,560 lights in the Limerick Tunnel and 763 on its approach roads. In 2011 it was costing DirectRoute around eur 130,000 per year to keep them all lit.

Meridiam was also aware that lighting technology had been developing rapidly, so it made sense to review the systems being used to light the Limerick Tunnel. Turning the lights off, or even down, was not an option. DirectRoute is responsible for maintaining light levels specified in its contract with TII and moreover, the aim was to add value. The opportunity was there to investigate ways of lighting the tunnel to the same high standards, but more efficiently.

A Cork-based consultant, Global Energy Management (GEM), supported DirectRoute’s evaluations of different options.

The result was a proposal for a new proprietary system of controlling the energy supplied to the lighting.

According to GEM’s figures, installation of Lighting Energy Controller devices (the system would require one LEC for each lighting circuit) could reduce the tunnel’s annual energy cost and the carbon emissions associated with its lighting, by 15 to 20%.

However, it was important for Meridiam to carry out its own indepth analysis of GEM’s proposal. Installing the LEC system would require an initial investment of approximately eur 77,000 and there is an element of risk attached to any new technology.

“The proposal from GEM certainly appeared attractive initially, but it was based on estimations of energy consumption. There are actually many different electricity tariffs associated with operation of the Limerick Tunnel and its approach roads,” says Direct Route’s General Manager, Declan Cahill. “We also had to bear in mind the fact that our rates of energy consumption vary a great deal, with the seasons and the time of day for example. We had to consider how long the LEC technology would last – how long it would be in place before it needed to be upgraded, so requiring investment again,” Declan adds.

Performance and reliability were vital considerations as well.

DirectRoute has a lot of different operational requirements it must adhere to, including a complex lighting specification. There are 12 different regimes of illuminance required in the tunnel alone, depending on the position within the tunnel, light levels outside and the direction of travel.

Would the LEC system present too much of a risk to DirectRoute’s operating performance? All of these things had to be included in DirectRoute’s assessment of the merits of installing the new technology.

“Ultimately we had the confidence to take on the risk, based on the analysis of the technology and the financial data,” Declan says. “We could have reduced our exposure to risk by sharing the capital expenditure and the returns with GEM, but we felt we didn’t need to. We had done a lot of analysis to support the decision.”

 

The final reckoning has vindicated Meridiam’s investment in the LEC system. Over the five year period from 2012 to 2016, electricity savings have come out at 18%, representing a total saving of eur 120,000. The payback period was three years and three months. There is also an environmental benefit: the energy saved corresponds to the average electricity consumption of 35 Irish households (1).

*(1) based on 2018 figures by the Commission for Regulation of Utilities, Ireland.

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