Transport Infrastructure Ireland issues a response to GADRA’s questions in relation to the proposed Metrolink project.
Transport Infrastructure Ireland give answers to GADRA’s Questions in relation to Metrolink :-
Thank you again for your email. In relation to your latest question, the tunnel alignment between Griffith Park and Albert College Park passes beneath approx. 30 properties. We have endeavoured to answer as many of your questions as possible below, but any further clarification can be provided at our meeting with you. Please also note that the plans being discussed are the current route alignment study and still at concept stage. Changes may be made in advance of the Railway Order application.
Q. What is the depth of the planned station in Na Fianna to platform level
A. The Griffith Park station will be a 3 level station with approximate platform depth of 23.5m below ground. The final depth of the station will be determined during the detailed design stage.
Q. What is the depth of each of the planned tunnels from Na Fianna to Collins Ave. Depth from ground level to top of tunnel please
A. The depth of tunnel between the Griffith Park Station and Collins Avenue Station varies between approx. 24m to 12m below ground. These figures are subject to change as design develops.
Q. Will TBMs being drilling both North and South from Na Fianna site
A. Two TBMs will start from Griffith Park station and bore southwards towards Charlemont. Two TBMs will start from a staging area north of Naul Road (near the Airport) and finish boring at the Griffith Park station box.
Q. From what launch site will the TBMs be launched to tunnel from Collins Ave Station to Na Fianna
A. Two TBMs will start from a staging area north of Naul Road (near the Airport) and finish boring at the Griffith Park station box via Collins Avenue station box.
Q. What alternative TBM launching Depots were considered?
A. During the course of the concept design, launching sites at both Charlemont and Naul Road were considered. There is insufficient space at Charlemont to locate such a temporary facility and a single tunnel drive from Naul Road would impact significantly on programme and risk. The Griffith Park site includes both a station box, is approx. half way between Naul Road and Charlemont, and offers sufficient space to accommodate a TBM staging area.
Q. Where does Cut and Cover occur along the route
A. A Cut and cover section is proposed north or the airport where the track passes under the R132 before the Fosterstown Station area, and a section of cut & cover is proposed at Charlemont between the station box and the tie-in point to Ranelagh.
Q. Where are the other TBM launching sites
A. The other TBM launching site is at the northern portal near Naul Road
Q. Will the planned Na Fianna launch site depot be in use 24 hours a day
A. Working hours will be the subject of an Environmental Impact Assessment, taking into account the type of site activities and proposed mitigation measures. The working hours will be ruled on by An Board Pleanála during the Railway Order process.
Q. Will the planned Depot at Na Fianna be lit up at night
A. There are no details at the moment of the site layout or arrangement.
Q. Is it planned to tunnel under Mobhi Road and Ballymun Road or is the planned route to be altered at the alignment stage to tunnel under the houses.
A. The twin tunnels are currently planned to be largely under the road. A small section north of Griffith Park station is passing under few houses, though this occurs where the tunnel is at its deepest. There are no plans currently to alter the alignment in this area.
Q. What is the distance between the two tunnels
A. A distance of 8 to 12 metres distance is the range currently being considered. This could be subject to change as the design further develops.
Q. Will both tunnels be side by side
A. The current design includes two tunnels running side-by-side throughout the alignment.
Q. Will both tunnels be at the same depth
A. The current design includes two tunnels running at the same depth throughout the alignment.
Q. What is the overall width of the footprint of the two tunnel including rock bolts etc.
A. As the design is not yet fully developed there are no details of rock bolts or any other structural support at this stage. The twin tunnels are approx.7m wide each (including the structural lining) with 8-12m spacing (in Griffith Park – Collins Ave. area).
Q. Where are the Ventilation /Intervention shafts positioned.
A. A location south of the airport has been identified as the intervention/ventilation shaft. Every station box will also serve as an intervention/ventilation point.
Q. What is the distance of the zone of Influence around the Station boxes, the Depots and the Tunnels .Is this measurement from the exterior of the tunnel wall or centre of tunnel.
A. A zone of influence (potential settlement) for the tunnels cannot be fully determined until the design has been developed. Regarding a zone of influence for the station boxes and depots, it is assumed this is the indicative construction zone and this is indicated on the drawings contained in the Public Consultation Document.
Q. How many properties are subject to CPO from Na Fianna to Collins Ave?
A. No properties between Griffith Park and Collins Avenue are currently subject to CPO.
Q. Where are the emergency exits along the route
A. Each station serves as an emergency exit route. There is also an emergency exit shaft proposed directly south of the airport boundary.
Q. When and where were the drones used and what privacy protection was afforded to residents in their private properties, schools and clubs during this process?
A. We responded to the queries on drones in our previous letter.
Q. When will you publish an alignment?
A. The alignment was formally announced on Thursday 22nd March.
Q. What size will the zone of influence be?
A. A zone of influence (potential settlement) for the tunnels cannot be fully determined until the design has been developed. Regarding a zone of influence for the station boxes and depots, it is assumed this is the indicative construction zone and this is indicated on the drawings contained in the Public Consultation Document.
Q. What is the margin of deviation
A. The Railway Order, when granted, will specify the margin of deviation. This cannot be provided at this stage.
Q. What is the planned depth of the station?
A. The Griffith Park station will be a 3 level station with approximate platform depth of 23.5m below ground. The final depth of the station will be determined during the detailed design stage.
Q. What is the planned depth to the top of the tunnel between Griffith Park West and Albert College Park?
A. The depth of tunnel between the Griffith Park Station and Collins Avenue Station varies between approx. 24m to 12m below ground. These figures are subject to change as design develops.
Q. Where is the planned launch site for the TBMs?
A. Two launch sites are planned for Griffith Park and at the portal north of Naul Road (near the Airport).
Q. What are the planned hours of work in our area, at station boxes and for tunnelling?
A. Working hours will be the subject of an Environmental Impact Assessment, taking into account the type of site activities and proposed mitigation measures. The working hours will be ruled on by An Board Pleanála during the Railway Order process.
Q. Are there are plans for a cross over tunnel between Griffith park west station and Collins ave Station?
A. There is no cross over tunnel between Griffith Park and Collins Avenue in the current proposal
Q. Do you plan/need to have a ventilation shaft in between Griffith Park West and Collins Ave station?
A. No ventilation shaft is currently planned between Griffith Park and Collins Avenue station.
Q. Has an Independent Expert been appointed to assist residents along the Metro route and what are the terms of reference for this expert role?
A. Appointment of independent experts is currently under consideration.
