The scale of the disruption likely to be caused by the construction of an on-street Luas system is clearly spelled out in the study by British engineering consultants, W.S. Atkins. However, it also points out that construction of an underground would cause "significant, but localised, disruption."
The study, a comparative analysis of surface and underground options for Dublin's light rail system, was commissioned by the Minister for Public Enterprise, Ms O'Rourke, and published by her yesterday after its presentation to the Cabinet.
"Construction of the surface option is likely to have a much more significant impact over a wide area of the city centre, with lane closures on some streets, increased delays at junctions and temporary bus routes, bus stops and footpaths," according to the report. It would cause disruption to traffic and pedestrians and result in a deterioration of the city centre environment for some two years. "However, these impacts will not be experienced throughout the city centre for the whole construction period," according to Atkins.
They would vary according to the location and timing of each phase of construction activity. "It is intended to carry out the works on each route on a section-by-section basis. Each section will be a few hundred metres long, the length being influenced by the distance between junctions." On parts of the Luas route such as Steevens' Lane, Benburb Street, Arran Quay Terrace, Chancery Street, Mary's Abbey and Abbey Street, "there will be insufficient road width for a single lane of traffic" and full road closure would be required during both the utility diversion and track-laying phases. Temporary routes and surfaces will be required alongside the works to maintain access to buildings. The main impacts are likely to be reduced accessibility and inconvenience to pedestrians, it says.
Dealing with the construction phase in detail, Atkins says enabling and demolition works would last for three months per section at a limited number of locations, primarily on the route section to the north of the Liffey, with no greater impact than that for general building works.
Subsequent works to divert gas pipes, telephone cables and water and sewerage services from the route of the Luas track would take three to six months per section, with parts of a street likely to be dug up and reinstated during different stages of the work. During the main construction phase lasting 12 months, earthworks and trackwork may require reconstruction from kerb to kerb, or even from building line to building line at certain locations north of the Liffey and in Dawson Street. Elsewhere, there would be "adequate capacity" for some traffic flow.
The study notes that Dublin Corporation's traffic management strategy will, when implemented, lead to "substantial reductions" in traffic flow levels on certain key sections of the Luas route through the city centre Luas route.
"Outside the city centre, the most significant traffic impact during construction of the surface option will be on Naas Road near Bluebell, where traffic in one direction will be restricted to one lane. This will be the case in each direction once the LRT is built and in operation," according to Atkins.
"Bearing in mind the need to ensure best use of scarce resources, the recommendation of the study is that the surface option is the most appropriate and cost-effective in meeting the transport needs of the city and providing capacity to meet long-term passenger demands," the consultants say.
However, this recommendation is based on a number of assumptions:
(1) That Dublin Corporation's proposals for rearranging traffic management in the city centre are implemented in full prior to the opening - and preferably prior to the start of construction - of the scheme.
(2) That the priority afforded by the light rail alignment within the city centre is shared with buses, to the overall benefit of public transport passengers in Dublin.
(3) That future extensions are planned with a view to avoiding overloading on individual route sections and maximising system efficiency in the longer term, by rationalising routes and introducing a "loop" extension linking the city centre with the Docklands area.
Traffic management measures include "environmental traffic cells" in the city centre from which through traffic will be excluded. Such traffic would have to use two concentric distributor routes, one following the canal ring and the other an inner ring.
The corporation's traffic management plan would also create public transport-only links within the central shopping area by permitting access to O'Connell Street, D'Olier Street, College Green and a portion of Nassau Street for buses, taxis and delivery traffic only; this is consistent with its millennium project for O'Connell Street.
A number of road schemes are also required to facilitate the plan, including the construction of a minor road linking Aungier Street and Mercer Street; and a new bridge costing £10 million across the Liffey at Macken Street.
