DART+ Coastal North Emerging Preferred Option
The preliminary options assessment studies have led to the identification of the Emerging Preferred Options for each of element of the project.
The project has been divided into sections describing the project in a north to south direction, as follows:
- General linear works
- Works around Drogheda MacBride Station
- Works around Malahide Station
- Works around Clongriffin Station
- Works around Howth Junction & Donaghmede Station
- Howth Branch Level Crossings
- Depot Works
General Linear Works
The project is predominantly located within the corridor of the existing railway and will deliver the necessary infrastructure to support the proposed increased train capacity. The works are necessary to provide for the planned increased capacity and enable a higher frequency of DART services. The provision of new infrastructure will comprise general linear works together with a number of localised interventions which are predominantly at stations. In the following section we introduce the range of general linear works required to modernise and electrify the existing railway line between Malahide and Drogheda as part of DART+ Coastal North.
Signalling and Telecommunications
- Signalling upgrades and additional signalling will be required between Malahide and Drogheda;
- Minor changes will be required to signalling between East Wall Junction (Tolka River), north of Connolly Station and Malahide;
- Upgrades to the telecommunication systems will be required route wide.
- An extension of the existing electrification equipment (OHLE) will be required as part of DART+ Coastal North. This will extend from the current limit of electrification at Malahide through to Drogheda. This will be similar to the OHLE currently used on the existing DART network;
- 8 new electrical substations will be required at intervals along the rail line between Malahide and Drogheda to provide power to the network;
- An assessment has been undertaken to review the existing clearances at all overbridges along the route in regard to future electrification requirements. The preliminary findings from the assessment conclude that a large proportion of the bridges have the necessary clearances and are unlikely to be impacted by the project. However, where existing bridges do not provide the necessary height for overhead electrification of the lines, options are being considered on a case-by-case basis, these include:
- Provision of specialist electrical solutions for the OHLE with reduced clearance;
- Lowering the rail track under the bridge;
- Modification of the existing structure;
- Removal of the existing structure and provision of a replacement structure; or
- A combination of the above.
OHLE will be required to be fixed and require localised modifications to underbridges/viaducts at:
- Malahide Viaduct;
- Rogerstown Viaduct;
- Balbriggan Viaduct;
- Laytown Viaduct.
- Modifications to existing overbridge parapets between Malahide and Drogheda will be required to ensure that parapets are imperforate, climb-resistant and at least 1.8m high. This will reduce the risk of people coming into contact with the OHLE;
- Interfaces with existing utilities, boundary treatments (including new retaining walls), drainage works, vegetation management and other ancillary works will be required along the length of the project.
- Existing user worked Level Crossing (XB001) located to the south of Donabate Station to be closed. This is as a result of the introduction of electrification and increase in train frequency on the Northern Line which significantly increases the safety risks at this level crossing to users of the crossing and to rail traffic.
Works around Drogheda MacBride Station
The works at Drogheda MacBride Station predominately relate to allowing a greater number of services to turn back at Drogheda to return to Dublin. There are currently an insufficient number of platforms to cater for the proposed service frequency at Drogheda MacBride, therefore an additional platform to turn back services is required.
The Emerging Preferred Option is to construct a new single platform on the Drogheda freight siding. This new platform will extend over the Dublin Road Underbridge necessitating widening of the bridge. At-grade access will be provided between the new platform and the existing Platform 1 and a new gateline will likely be installed. The Drogheda freight siding will be slewed (realigned) and railway infrastructure modified as necessary.
In terms of train stabling, the existing Drogheda freight siding and a new stabling track, located adjacent to the depot, will be utilised. The new stabling track will require works to the existing landscape bund. The extent of works to the bund will be developed in the next stage of the design process.
Works around Malahide Station
The works at Malahide relate to the provision of new infrastructure which will facilitate a greater number of train services to turn back at Malahide and return to Dublin.
The Emerging Preferred Option is to introduce a turn back facility constructed on the eastern side of the existing tracks, immediately north of Malahide Station, between the Strand Road Underbridge and the Malahide Viaduct. The option requires widening of the rail corridor and the existing embankment on which it is situated. This widening will be facilitated by the construction of a retaining structure which will be built alongside the realigned track.
New OHLE and signalling installations, as well as modifications to the existing systems, will be required. The turnback will have an illuminated staff walking route alongside it.
Works around Clongriffin Station
The works at Clongriffin Station relate to allowing a greater number of services to turn back at Clongriffin to return to the centre of Dublin.
The Emerging Preferred Option is to introduce a new loop to serve a platform to the east side of the station. It is proposed to use the platform face that was constructed when the station was originally built but is not currently served by any tracks. The original station construction anticipated this construction requirement and therefore it will have minimal impact on the station building/existing infrastructure.
Modifications will be made to the track alignment to the south of the station to allow trains to access the new platform. New OHLE and signalling installations, as well as modifications to the existing systems, will be required.
Works around Howth Junction & Donaghmede Station
- The works around Howth Junction & Donaghmede Station are linked to facilitating increased capacity on the Northern Line and relate to allowing a greater number of DART services to turn back at the station.
- The Emerging Preferred Option includes construction of an extension to the existing Platform 2 to allow the platform to be used by terminating services from Howth without impacting on services running along the Northern Line. Track modifications will be made to include a new crossover to the east of the existing station platforms. Alterations and modifications to existing OHLE, signalling and telecoms systems will also be required.
- As part of the works to facilitate a shuttle service on the Howth Branch, improvements to station facilities will be considered in order to provide a satisfactory customer experience. These will be developed in greater detail as the project progresses through to Public Consultation No. 2.
Howth Branch Level Crossings
The proposed changes to the Howth Branch will facilitate the introduction of a shuttle service at regular intervals between Howth and Howth Junction & Donaghmede stations.
These changes will result in an increase to both train service frequency and overall carrying capacity along the Howth Branch, as well as improvement to the reliability of associated timetabling. Services are expected to increase from the current frequency of 9 trains in a 3-hour AM peak period to a future frequency of 18 trains.
The Emerging Preferred Option for the Howth Branch level crossings is for them to remain open, as they are currently. Initial assessment of the four existing level crossings along the Howth Branch line has indicated that these level crossings can continue to operate while still providing a more efficient service overall.
Further survey data will be collected prior to Public Consultation No. 2 to validate the model and assumptions, and this information will be used to establish if the proposal to keep the level crossings in operation is feasible, or if more significant interventions are required at the crossings.
There will be localised works at Drogheda and Fairview Depots to modify the facilities to cater for the change in rolling stock. These modifications are predominantly internal to the buildings although they will also encompass some localised exterior changes to some track work and systems. The depot at Drogheda MacBride Station will be electrified with OHLE.