The construction of a world record-breaking bridge in Ireland’s southeast, which will redefine expectations for bridge engineering both nationally and internationally, and a coastal mobility route are among six projects to be recognised by Engineers Ireland and ESB in the Engineering Excellence Digital Series. 

Unveiled recently in recognition of the work of Ireland’s talented engineers, the series aims to recognise and showcase inspiring engineering endeavour in 2020 and its positive impact on society. 

Here we examine the two winning projects – and those that were highly commended – in the 'Infrastructure and Buildings' category.

Winning project No 1

N25 New Ross Bypass PPP incorporating Rose Fitzgerald Kennedy Bridge over River Barrow

Constructed by BAM-Dragados with the detailed design being undertaken by Arup, in collaboration with Carlos Fernandez Casado, it comprises a 14km bypass which includes an 887m long, nine-span, three-tower extradosed Rose Fitzgerald Kennedy Bridge.

The structure is part of the N25 New Ross Bypass scheme which strengthens connections between the communities of Wexford and Kilkenny, while also enhancing local and regional connectivity.

By reducing congestion, improving road safety and opening economic opportunities, the bridge has improved the lives of residents on both sides of the River Barrow and, indeed, the much wider community.

Constructing the longest bridge in Ireland required significant temporary works, including two temporary piers, a push-pull prop for the balanced cantilever construction and a temporary artificial island to facilitate construction of the main central pier where the piles extend 32m below ground.

2D hydrodynamic modelling was carried out to estimate the potential changes in the flow regime associated with both the temporary island and the permanent in-channel bridge pier.

Detailed ship impact analysis was carried out for the central pier to resist potential loads up to 17MN, taking account of the river bed and bank topography and dissipation of energy of the ship while approaching the foundation, along with the non-linear behaviour of the soil structure displacements during impact.

The bridge includes four extradosed concrete spans; two of which are 230m in length. The construction method, balanced cantilever, in conjunction with the asymmetry of the towers cables on each tower, led to a main cantilever of 140m at the longest stage of construction, a world record for concrete deck extradosed bridges.

Structural analysis tools, such as explicit time dependent creep curves and step-by-step non-linear iterative analysis, were used. The largest cables consist of 125 strands and went through a full-scale fatigue test of two million cycles in a lab in Chicago, one of only two labs worldwide that have the capacity to test cables of this size.

Fire engineering design investigated the effects of various scenarios of vehicle fires on the bridge deck. Thermal blankets were designed for the lower part of the cables.

The consciously chosen asymmetry of the three towers, with the central tower slightly higher than the side towers, provides this structure with unique personality, contributing to the Wexford-Kilkenny skyline.

It will stand as a world-class 21st century structure that enhances this part of the country while also serving as a key link in local and regional infrastructure connectivity.

The opening of the N25 New Ross bypass on January 29, 2020, was a landmark day for the designers and contractors and for Transport Infrastructure Ireland, Wexford County Council, Kilkenny County Council and the technical advisers for the scheme, Mott MacDonald Ireland.

Winning project No 2

The Coastal Mobility Route

The Coastal Mobility Route, delivered by Dún Laoghaire-Rathdown County Council with project partners, Clonmel Enterprises and the National Transport Authority, is a two-way segregated cycle-lane with buff surfacing, extending more than 3.6km in two uninterrupted sections from Newtown Avenue in Blackrock to Coal Quay Bridge, and from Queens Road to the Forty Foot in Sandycove. With a further 0.9km section through quiet streets, the route is about 4.5km in length.

Due to restrictions in movements associated with the pandemic, there has been a significant increase in walking and cycling, with a 100% increase in cycling recorded on coastal routes in May 2020, compared with the same period in 2019. 

Previously, pedestrians often faced situations where there was not enough footway width to maintain two-metre physical distancing, which led to people stepping off the footpath and potentially colliding with oncoming traffic.

The restrictions also had severe implications to local businesses trying to reopen, but unable to accommodate the public on the available footpaths. 

Delivered in less than eight weeks, the project reconfigured the public realm to respond to COVID-19 risks, creating safer and improved facilities for walking and cycling, but also enhancing the public space to provide safe and inviting places, that the public can visit, spend time in and enjoy while supporting local businesses as they reopen.

Parking along the coastal route of roads was largely unaffected. Existing public transport, including bus routes and bus stops, remained unaffected by the proposed cycling corridor.

With about 20,000 cyclists utilising the route each week, the Coastal Mobility Route now promotes and facilitates a necessary shift to walking and cycling, along this strategic coastal transport corridor, by delivering safe and enjoyable sustainable transport for all ages and abilities.

It is in line with current government public health advice, where people are advised to walk or cycle if they can and to avoid using public transport, unless it is absolutely necessary.

The temporary cycling corridor presents a significant opportunity for local businesses and tourism, creating safer and improved facilities for walking and cycling, but also enhancing the public space to provide not only safe but also inviting places that people will want to come visit, spend time in and enjoy.

The project has also enabled pedestrian and cycling links between Booterstown, Blackrock, Monkstown, Dún Laoghaire, Glasthule, Sandycove and Dalkey.

Highly commended projects

• N56 Kilkenny to Letterilly Road Scheme 

The N56 Kilkenny to Letterilly Road Scheme (by Fox Building & Engineering Ltd, Maccaferri and Gavin and Doherty Geosolutions) is situated in one of the most scenic and pristine environments in Ireland. This scheme addressed a section of the N56 which narrowed significantly as it rounded above the Gweebarra River near Lettermacaward.

The employer, Donegal County Council, envisaged widening the road using a combination of bored piles, kingpost piles and precast panels.

N56 Kilkenny to Letterilly Road Construction Scheme

However, a value engineering solution delivered by the project team, consisting of Fox Building & Engineering Ltd, Maccaferri and Gavin and Doherty Geosolutions, removed all of the concrete and steel works and replaced the slope with a reinforced soil slope up to 18.5m high while still allowing traffic to pass during construction.

The new slope’s grass façade provides an attractive finish and a much-enhanced alternative to concrete panels. The geogrids, high-quality fill materials and gabions used significantly less embodied energy than the specimen piled design and facilitated the safe and reliable structure that fits in with its beautiful environment.

• Osberstown sludge treatment facility 

This scheme (by Veolia) successfully increased the capacity of the Osberstown wastewater treatment plant for Kildare County Council and Irish Water so that it now serves a population equivalent of 360,000 people and numerous local industries. 

Following this success, the Veolia team were tasked with the challenge of upgrading the adjacent Osberstown sludge treatment facility. This facility processes all wastewater sludge for Co Kildare.

The upgraded wastewater treatment plant in Osberstown

Veolia’s ground-breaking approach to the project combined innovative technologies to deliver advanced anaerobic digestion to create an energy self-sufficient sludge treatment facility that reduced CO​2​ emissions by more than 8,000 tonnes per annum. 

It formed a ‘blueprint’ for sustainable phosphorus reuse well into the future and created huge savings, including about €9 million of CAPEX, ensuring the viability of the project, and €2 million per annum (at design loading) of OPEX.

The project also delivered substantial energy savings that will allow the equivalent of more than 2,700 households to be provided with thermal energy from natural gas.

• Royal Canal Premium Cycle Route 

Phase 2 of the Royal Canal Premium Cycle Route (by Roughan & O’Donovan Consulting Engineers, Grafton Architects, Blackwood Associates Architects, Cunnane Stratton Reynolds, Kevin Cleary & Associates, CRDS Ltd and Jones Civil Engineering Ltd) runs from Sheriff Street to North Strand Road, and is a truly transformational project.

By reusing an extensive brownfield site in Dublin’s inner city, the National Transport Authority and Dublin City Council have opened up a previously underused section of the Royal Canal to provide an important commuter artery for cyclists and pedestrians and create a high-quality amenity – for leisure, exercise and social contact – for the local community.   

Located in the heart of Dublin’s north inner city, the project weaves together a high-quality cycle track, footway, linear park, pontoon, viewing plaza and a multispan viaduct spanning the live rail into and out of Connolly station to create a place for locals to cycle, walk the dog, meet their neighbours and build the social glue that binds communities together.

This scheme has given the people of inner-city Dublin an amenity to be proud of, a renewed sense of community and a reconnection with the area’s historic infrastructure and green space.

To find out more about the Engineering Excellence Digital Series, visit: https://www.engineersireland.ie/Professionals/Events/Featured-events/Excellence-Awards/Engineering-Excellence-Digital-Series