Grontmij, part of the McCarthy Hyder Grontmij joint venture, has played an integral role in the design team throughout all phases of the N4 / N6 Kinnegad - Kilcock Motorway Public Private Partnership (PPP) Scheme; the first PPP scheme to be awarded in Ireland.

Alleviating congestion and improving safety

The N4 / N6 national primary roads formed part of the strategic road network linking Dublin to the west of Ireland. The previous single carriageway routes carried significant traffic volumes (exceeding road capacity) and caused congestion problems. The new motorway and dual carriageway sections led to a reduction in journey times, a safer road corridor and provided benefits to the local communities along the length of the scheme.

Detailed design of drainage and pavement

Grontmij was responsible for the detailed design of various highway design elements including drainage and pavement. The drainage element of the design utilised over the edge drainage with treatment and attenuation provided within a network of trenches.

The pavement design was generally based on the DMRB but included sections of analytical design to overlays where the existing pavements were incorporated into the works making the best use of the existing asset.