Dublin Luas Green Line Extension Opened

The Dublin Luas Green Line Extension to Cherrywood was officially opened by An Taoiseach, Brian Cowen, T.D. on 16 October 2010. The new 7.5km line cost €300m to build and is expected to add over two million passenger journeys a year to the tram network.

As engineers responsible for the three major viaducts and other bridges at a combined value of over €33m, RPS was invited to the opening ceremony which concluded with a journey to Cherrywood on the Luas.

Opening the project, Brian Cowen, spoke of the importance of public transport and how Dubliners have embraced the Luas. He acknowledged the hard work and effort of the Railway Procurement Agency (RPA), their consultants and contractors on delivering a project of such scale that it involved two separate viaducts across the M50 motorway, as well as other bridges and underpasses. The project adds nine new stops to the Luas Green Line.

Frank Allen, CEO of the RPA, noted that development along the line had not occurred as originally envisaged, but was confident that the new line would encourage growth in due course

RPS staff joined RPA representatives, political leaders and other dignitaries on the Luas journey to the new destination at Cherrywood - the official commentary along the route described the RPS bridges and acknowledged the RPS underpass at Spine Road as the longest underpass on any of the Luas lines.

RPS has been involved in the Luas Line B1 Extension from the early stages, having produced the Environmental Impact Statement. In 2005, we were appointed by the RPA to provide civil and structural engineering services on the project (construction contract value €40 million). RPS also provided assistance to the RPA during the Rail Order Oral Hearing and provided technical support to the RPA during the construction stage. RPS had previously produced EISs for the two existing Luas lines linking Dublin City with the southern and western suburbs.

Luas (the Irish word for ‘speed’) is the light rail system operating in Dublin. The network facilitated over 25 million passenger trips in 2009. The existing Green Line is 10km in length and was opened in September 2004, linking St. Stephen’s Green in the City Centre with Sandyford Industrial Estate in South Dublin, one of the largest industrial centres in Dublin and home to major corporations such as Microsoft, Vodafone, and Merrill Lynch.

Construction of the 7.5km extension to the Green Line commenced in March 2007 and involved the construction, installation and operation of a twin tracked light rail transit system with designed provision for future upgrade to Metro. The new extended line connects Cherrywood in South County Dublin to St. Stephen’s Green, where it will link to the proposed Metro North Project, for which RPS is currently involved at Best and Final Offer Stage.

For the line extension, two elevated crossings of the M50 Motorway (Dublin’s busiest arterial route) were necessitated, as well as a crossing of a large ravine in Leopardstown adjacent to Glencairn House, the official residence of the British Ambassador to Ireland. The construction of the structures presented unique challenges as construction took place on a very confined urban site, with complete night time shut downs of the M50 Motorway required in order to complete construction of two bridges.

Due to the confined nature of the site, an extremely curved structure was required at Brewery Rd. Roundabout. The structure turns ninety degrees in plan over a busy junction and utilised specially designed pier supports which did not restrict vehicle site lines on the busy road network.

RPS was responsible for the design and preparation of construction documents for four new major bridge and viaduct structures, a cut and cover tunnel and over 1km of track on podium and retaining structures. Over 1.5km of the 7.5km light rail line is supported on RPS designed structures.

The project was significant for RPS as it was the first major civil/structural light rail engineering design and construction contract with the RPA and the bridges are also the longest steel composite structures designed by RPS in Ireland.