Quantifying Noise Impact of Dublin Airport's North Runway Departure Routes: An EIA-Conformance Gap Analysis

Dublin Airport's North Runway operates on departure routes that differ materially from those assessed in the 2004/2005 Environmental Impact Statement (EIS) underlying the 2007 planning consent, a point not disputed in the public record. This report quantifies the spatial distribution of population exposure associated with that divergence. It does not assess legal compliance with the EIA Directive or planning permission; rather, it provides a reproducible geospatial comparison of assessed and operational routings. SID-compliance corridors are constructed around the published SID ("Routes Flown") and two EIS-consistent alternatives: Strict 5NM (a 5 NM straight segment before any turn, the legacy 28L convention) and Designed (Strict plus a 1.5 NM extension to avoid direct overflight of Dunboyne). Buildings are counted from OpenStreetMap, population estimated from 2022 CSO Small Area data; 28L operations are the existing exposure baseline. Under the Routes Flown, an estimated 13,923 residents (4,008 buildings) are newly directly overflown that were not overflown by three decades of 28L operations, against 998 (330) under Strict 5NM and 1,008 (333) under Designed: 13× more residents and 12× more buildings than either EIS-consistent alternative, within a regulator-anchored 1.5 km corridor (UK DfT track-keeping swathe). At the canonical 1.5 km half-width, the Routes Flown corridor has zero overlap with the 28L Actual corridor. Against the 28L baseline, the Routes Flown reduce the overflown population by 31%; the Designed alternative would reduce it by 86%, a difference of ~11,000 people. Each EIS-consistent alternative is realisable at standard 15-degree bank and 250 knots; no geometric or procedure-design constraint was identified that would preclude these alternatives under standard departure design assumptions. Full operational validation (ATC, separation, airspace integration, procedure redesign) is outside the scope of this study, nor is regulatory compliance adjudicated. The analysis adopts a single-event (LAmax-based) spatial framework to bound the lateral extent of overflight exposure and does not model cumulative noise metrics (Lden, Lnight). A corridor-width sensitivity sweep finds the point estimates move 10 to 25% across defensible half-widths. At the ICAO RNAV-1 XTT of 1.852 km the newly-overflown count is 17,137, 22.7% above the 1.5 km canonical: the canonical is the narrower of the two named regulator anchors and is conservative against interest. The order-of-magnitude disparity between the Routes Flown and any EIS-consistent alternative holds across the full 4×3 matrix.