Gas Networks Ireland (GNI) has been refused permission to undertake a safety upgrade to gas infrastructure in Drumcondra in Dublin because of the potential adverse impact on the “character” of an historic bridge.

The State gas company had been granted permission by Dublin City Council last September to install a two-metre high fibreglass structure to house gas regulating infrastructure beside Binns Bridge on the Royal Canal close to Croke Park.

However, the decision has been overturned by An Bord Pleanála following an appeal by the Mountjoy Square Society, which said the structure would have a “permanent, grossly detrimental effect” on the setting of the 18th-century bridge.

The gas company said it applied for the development to upgrade the network in the area to comply with current safety legislation. This involved the removal of old underground infrastructure and its replacement with an “above-ground enclosure” 5m long, 1.5m wide and 2.1m high.

The infrastructure involved is a “district regulation installation” used to reduce the pressure of gas feeding more than 4,000 customers in the north Dublin area.

The old below-ground installation is prone to flooding which can jeopardise the security of supply and is inadequately ventilated, GNI said.

The company is undertaking a programme of replacement of the underground regulators with above-ground facilities, and was starting with those “most critical to the security of supply” which included the Binns Bridge installation.

The city council’s conservation officer, Clare Hogan, said the installation would not affect the historic fabric of the bridge, which is a protected structure, and she accepted it was a “necessary piece of infrastructure that will facilitate safe supply of gas to 4,000 homes”.

She noted that “earlier below-ground structures have been found to be unsafe” and “alternative locations were not viable”.

However, An Bord Pleanála said the structure would form an “obtrusive feature” that would “adversely impact on the visual amenities, character and setting of the protected structure and would fail to integrate in a satisfactory manner with its sensitive receiving environment”.

A spokesman for GNI said it needed time to assess the board’s decision before determining its next step. The existing facility “poses no safety risk to the general public” he said.

“The purpose of the works was to modernise the installation, reduce the risk of flooding, and to enhance the safety of the installation, particularly from the perspective of crews engaged in operations and maintenance activity.”

Binns Bridge is actually made up of two distinct limestone and granite bridges, a single-arch bridge built over the canal in 1795 and a double-arch bridge over the adjacent rail line dating from 1864. It is named after 18th century politician John Binns who was involved in the financing of the Royal Canal project.