CEEQUAL Excellent (79.3%) – Whole Project Award
Version 4, Aug 2011 | Derry, Northern Ireland
The A2 is part of the Northern Key Transport Corridor connecting Belfast to Londonderry via Coleraine. It is the main road connecting Limavady to Londonderry and provides links to the Maydown and Campsey industrial zones, and to the City of Derry Airport, the key air transport hub in the Northwest of the province.
The scheme diverts traffic onto a dual carriageway constructed between the Maydown roundabout and the City of Derry Airport. This upgrades sections of the existing single carriageway road and also includes some off-line construction.
The 6.2 km length of dual carriageway consists of two lane all-purpose road which is 7.3m wide with 1.0m hard strips. The combined horizontal and vertical alignments follow the topography closely to minimise environmental impact on adjacent areas. At-grade junctions are incorporated in the scheme, with three new roundabouts located at the heavily trafficked intersections at Campsey, Broadbridge and the City of Derry Airport.
The scheme involved amendments to access onto the A2 as there are several private and agricultural accesses which conflicted with the scheme. Some isolated accesses were retained and traffic movements were restricted to left in/out turning.
The main aims of the scheme are to reduce congestion, journey times and delays and accommodate increasing traffic flows, whilst improving safety.
Considering Alignment Options
The land take and environmental impact of various route options were considered in the early stages of scheme development. An alignment was chosen which made efficient use of land resources. 32% of new scheme uses the existing footprint of the A2 and the scheme has avoided areas of high ecological and landscape value.
The needs of a variety of user groups have been considered in the design of the project. This includes car drivers, cyclists, pedestrians and disabled users. The design incorporates a footbridge and underpass which improves safety and permeability for pedestrians & cyclists where they would previously have had to cross busy roads. Bus stops and bus bays have been integrated into the design to make public transport reliable and accessible.
The new underpass and footbridge area will be lit. This improved lighting scheme (designed to minimise light pollution) will improve security within this area. Lighting will be vandal proof and set into the ceiling of the underpass for its entire length.
The scheme was designed to avoid mature trees and hedgerows in the vicinity of the works. The project team actively considered the retention of all trees as part of the design, but the retention of all trees was not possible due to site constrains during the site clearance operations.
A tree survey by a qualified arboriculturalist was carried out which confirmed that mature trees, hedgerows or Tree Preservation Orders (TPO) trees were avoided by the scheme, and only immature trees on no real value were removed.
The scheme has replaced significant areas of farmland (grassland and cereals) with new native species habitat including oak woodland, species diverse grassland and native species hedge planting.
A mammal underpass has been incorporated into the scheme to allow safe access for otters across the road.
An Archaeological Watching Brief for the construction work was prepared, consulted upon and completed. Finds were discovered at six sites which were under the main footprint of the road. This lead to a 12 week excavation programme which uncovered finds including a Neolithic house, Bronze Age burial plots, cremation pits, pottery and tools. Reports on the findings have been prepared and submitted to the Northern Ireland Environment Agency.
Carbon and Energy
A Life-Cycle Carbon and Energy Assessment was completed for the project, covering extraction of raw materials, processing, manufacture and transportation. This resulted in a list of improvements being drawn up and implemented for the project. This has reduced carbon emissions associated with the project by an estimated 9% (1,633 tCO2).
Examples of improvement measures for the project included use of road signs and bollards which do not require illumination, a low energy lighting system and a transport plan to minimise staff travel to and from the site. The travel plan alone represents a saving of approximately 260 tonnes of Carbon Dioxide.
The project achieved the following:
- 99% of excavated material has been reused on site
- 95% of existing structures present on site were incorporated into the project
- All topsoil was retained and reused on site
- 28% of materials were sourced from non-virgin sources. The contractor sought an exemption to use 70,000m³ of material from another local construction site for fill
- 50% of material from demolition was diverted from landfill.
Relationships with the Local Community
The project went through a programme of extensive consultation covering all stages of the project and a Public Inquiry. There is clear evidence of consultation informing design.
During construction, community concerns were managed by providing advanced notice for road closures and noisy works. A member of the project team managed community comments and concerns.
The construction team participated in several community engagement actions, including:
- participating in the KickStart2Work scheme run by Derry City Council to enable long term unemployed people to get back into work
- employing a school crossing guard to provide reassurance over safety outside a local school
- liaison with the local police and half marathon organisers to ensure safe passage of 180 police taking part in a sponsored walk and half marathon runners
- facilitating a visit from college students to learn about highway engineering.