north-south corridor
Northern Connector Project Northern Impact Report northern connector
For more information
For more information, to make an enquiry or join the mailing list contact the Northern Connector project team. Phone: 1300 793 458 (interpreter service available) Email: [email protected] Visit the website: www.infrastructure.sa.gov.au and then follow the prompts.
1 www.infrastructure.sa.gov.au 1300 793 458 2
Project Impact Report Volume 1 An environmental, social and economic assessment north-south corridor northern connector
Part C. Description of the project
6 Planning, design principals and standards 7 Development of the Northern Connector project 8 Project description 9 Construction and operation
Project Impact Report Volume 1 An environmental, social and economic assessment Part C Part Northern Connector Project Impact Report Chapter 6 – Planning and design principles and standards
6 Planning and design principles and standards
6.1 Design principles
The design principles for the Northern Connector project, derived from the project objectives (Section 1.2), relate to: . integration of the road and associated structures into the rural and urban landscape . safety for road users, rail operators and the community . enhanced efficiency for road freight, rail freight and private vehicles . high level of service for all road users . integration of rail line with the existing rail network . integration of rail line with the expressway and structures . high quality infrastructure . sustainable outcomes . opportunities for economic development . constructability . strong landscape and urban design . minimising environmental impacts . minimising socioeconomic impacts.
6.2 Road
6.2.1 Design standards
The design standards for the project are comprehensive and focused to achieve project objectives, particularly for road safety, high quality infrastructure, efficiency for freight and private vehicle movements, and integration with existing land form. The Northern Connector would be designed in accordance with the Department for Transport, Energy and Infrastructure (DTEI) Road Design Standards and Guidelines. Design references include: . Austroads Guide to Road Design . Austroads Guide to Traffic Management.
6.2.2 Design speeds
Posted and design speeds for the new expressway, extension of existing arterial roads and redevelopment of local roads are shown in Table 6.1.
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Table 6.1 Road design speeds Posted Design Road speed speed (km/hr) (km/hr) Northern Connector (as for Northern Expressway) 110 120 Port Wakefield Road (between Northern Expressway and 80–90 90–100 Salisbury Highway) Northern Connector approaching South Road Superway 90 100 (transitioning from 110 km/hr to 90 km/hr posted speed) South Road Superway (elevated roadway) 90 100 Salisbury Highway 90 100 Port River Expressway 90 100 St Kilda Road (to Robinson Road) 80 90 Waterloo Corner Road extension 60 70 Globe Derby Drive 60 70
Design speed applies to individual geometric elements and is the speed used to coordinate design parameters such as: . sight distance . vertical curvature . horizontal radius . superelevation . side friction demand. By definition, design speed must be equal to, or greater than, the 85th percentile speed — the speed at, or below, which 85% of cars travel under free flowing conditions past a certain point. Of all car drivers, 85% will be slower than, and 15% will be faster than, this speed. The posted speed limit (i.e. the speed limit that is enforced) is below the design speed to ensure that a safer speed will be maintained by the majority of vehicles.
6.2.3 Minimum horizontal radii
Minimum design criteria have been selected for the Northern Connector and the minimum horizontal radius (the smallest/tightest curve to be designed on the expressway) adopted for the design speed of 120 km/hr was 1,350 m. This minimum radius will be adopted along the length of the expressway, except for the transition area on the approach to South Road where the reduced design speed of 100 km/hr allows for a radius of 925 m to be applied.
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6.2.4 Maximum superelevation
Superelevation (the slope by which the outside lane of a road curve is raised above the inside lane) would be applied to the horizontal radii to achieve design speed with the maximum 3% to be applied for the whole Northern Connector route.
6.2.5 Vertical alignment design parameters
The Northern Connector grade (slope of the road) would be 0–3% under normal situations. The minimum grade would be 0.5%, except at the Cheetham Salt Ltd Dry Creek salt crystallisation fields where 0.5–5% may be adopted, and the maximum 5%.
The grades of the on-ramps and off-ramps will be in the range 3–5%. Local roads associated with the project will be constructed at grades of 3–5%, with a 0.5% minimum grade. The minimum vertical crest curve (a convex curve that connects sections of the road) would have a rate of vertical curvature (K) = 140 for cars (120 km/hr); the minimum vertical sag curve (a concave curve that connects sections of the road) would have a K = 61 for cars (120 km/hr).
6.2.6 Design philosophy for interchanges
Vehicles exiting the Northern Connector will have to significantly decrease their speed. Exit ramps will therefore be designed using reverse curves (two circular curves with opposite angles or an ‘S’ curve). Speed is reduced through each curve, a method considered safer than the traditional method of additional road length in which to decelerate.
6.2.7 Pavement
The pavement used on Northern Connector carriageways will be chosen during the detailed design phase of the project according to geotechnical conditions and information from the detailed geotechnical investigation. Several heavy-duty options and surface treatments are being considered, including full-depth asphalt.
6.2.8 Road safety
Road user safety has been designed based on expected traffic composition (types of vehicles using the road) and will be enforced through posting appropriate speed limits for the road conditions. The following elements of Northern Connector road design and installations are expected to further increase safety: . high standard of geometric design . wide, sealed shoulders with sufficient space for vehicles to stop . unobstructed recovery width for errant vehicles beyond the shoulders
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. crash barriers with appropriate approach and terminal treatments . design of stormwater structures to minimise risk of hazard . crash barriers on all bridge structures and approaches . wide lanes allowing safe operating conditions . pedestrian and cycle pathways separate from road and protected by barriers (where necessary) . advance signage . public lighting constructed with frangible (breakable) poles . appropriate sight distances at intersections . intelligent transport systems.
6.2.9 Sea level rise
Outer Harbor sea level data, recently examined by Australian Water Environments (2008), suggest that a safe embankment level of 3.45 m Australian height datum (AHD) be adopted. This height will allow for sea level rise up to the year 2050. The Northern Connector corridor width will allow for embankments to be raised to 4.11 m AHD to cater for sea level rise to the year 2100.
6.3 Rail
6.3.1 Design standards
The National Code of Practice has been adopted as the standard for horizontal alignment designs of the Northern Connector rail, with the following clarifications: . design speed — 115 km/hr . where possible a minimum desirable curve radius of 850 m . plate F clearance requirements.
6.3.2 Rail horizontal alignment design
The following factors influenced the design of the Northern Connector rail line: . functionality of freight line connections . freight line speeds . branch line design speeds . access to the track for maintenance vehicles.
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Functionality of freight line connections A key consideration is access to Dry Creek via existing entry lines. It is assumed that maintaining the existing entry would allow continued rail depot operations on site; however, the yard and redesigning operations may need to be reconfigured.
Existing freight line speeds The current speed on the Outer Harbor spur of the existing freight line of 50 km/hr will be used as a guide for other lines.
Access for maintenance vehicles Maintenance vehicles will access the rail track via a vehicle track adjacent to the rail track. This maintenance track will be accessed from each end of the Northern Connector and possibly along the route from the road carriageway.
6.4 Shared-use path
A sealed 3.0 m wide shared-use path located in the Northern Connector corridor will be designed for commuter and recreational use by pedestrians and cyclists. The shared-use path will continue on from the 23 km shared-use path (the Stuart O’Grady Bikeway) in the Northern Expressway corridor. The exact alignment of the shared-use path will be determined during the detailed design phase. Achieving a safe crossing over Port Wakefield Road will be a priority. Design standards will be in accordance with AustRoads, based on Figure 5.29(C) of Road planning and design manual (Main Roads 2001–2008). The Northern Connector shared-use path would comply with Disability Discrimination Act 1992 requirements.
6.5 Urban design framework
6.5.1 Vision for the Northern Connector
The urban design vision for the Northern Connector is to create a unified and elegant design solution and an engaging experience for road users and adjacent communities by fully integrating the structural form of the bridges and road infrastructure with the street furniture, landscaping and wetland environments. The Northern Connector will be sensitively integrated with the northern Adelaide plains landscape and create a distinctive sense of place. Extensive natural features along the corridor will be highlighted and the visually interesting patterns of development acknowledged.
6.5.2 Urban design objectives
The Northern Connector provides the opportunity to sensitively manage and integrate structural, landscape and environmental features along the project corridor.
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The urban design objectives supporting the vision have been developed with an understanding of the landscape qualities of the area and the desire to ensure a level of urban design consistency with what has been constructed on the Northern Expressway and what will be constructed for the South Road Superway.
The urban design objectives for the Northern Connector relate to the: . architectural character of major civil and structural engineering components such as bridge form and detailing . character of minor infrastructure elements (e.g. noise barriers, reinforced earth walls, retaining walls, fencing, gantries, major signage structures, lighting, field cabinets and street furniture) . materials, colours and surface finishes to be used . public art elements . environmental elements such as revegetation works and landscape and wetland design. The urban and landscape design objectives are: . sustainability — create an ecologically sensitive road and rail corridor, building on existing remnant and significant landscapes, improving urban biodiversity and providing habitat for fauna species . experience — create a unique, fresh and contemporary journey experience for users of the Northern Connector and consider the views of the road from adjacent properties . response — adopt a design aesthetic that respects the existing (and future) context, built form, morphology, land uses and landscape characteristics through which the Northern Connector passes . character — provide a level of visual consistency with the Northern Expressway and South Road Superway projects and integrate appropriate design elements from each rather than attempting to introduce a completely new design language or aesthetic . integration — understand the subtle differences along the project corridor and integrate changes in character into the landscape treatment of the corridor.
6.5.3 Urban design principles
The urban design principles that support the urban and landscape design objectives of the project are: . sustainability: - select appropriate, long-lasting materials that will age gracefully and require minimal maintenance - select material that are energy efficient
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- use water-sensitive urban design principles, retain and reuse stormwater within the corridor, where feasible, and integrate with adjacent stormwater management reuse schemes - select plants and landscape treatments that will have low irrigation requirements during establishment - use endemic and native species to create a habitat corridor and encourage increased urban biodiversity - enhance current areas of biodiversity and habitat value, principally in significant landscape areas with remnant and indigenous vegetation - protect areas of remnant or indigenous vegetation - use local sources of materials to reduce transport requirements . experience: - select materials and proportion spaces to give a variety of visual, audible and tactile experiences along the road and shared use path - ensure landscape responses reflect the natural and cultural environment - create an experience of progression while moving through the unique landscapes of the project area, through urban design treatments and installations at interchanges - ensure appropriate scale installations of urban design features to ensure legibility and appreciation of road users while travelling at high speeds - use varied landscape treatments along the corridor to allow a sense of journey for road users - highlight features of the existing landscape character and take advantage of opportunities for scenic views - ensure views to natural features (e.g. Barker Inlet, Mount Lofty Ranges) are maintained and enhanced . response: - reflect existing land uses and patterning of the project area in the landscape treatment - instil a sense of belonging with the appropriate response in landscape treatment that empathises with the unique and diverse landscape qualities - respond to landscape patterns and forms by bringing them, where possible, into the road corridor (e.g. emulate roadside or shelterbelt planting in the road corridor, use landscape elements to acknowledge the previous land patterns of the area) - respond to indigenous ecologies once prevalent in the area through appropriate plant selections . character: - carefully consider composition, detailing and material selection of architectural elements - creatively resolve forms, materials, colours and surface finishes
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. integration: - design considering simple yet robust structures and design elements that integrate with the context of the surrounding area - reduce intrusion into the local landscape character area through integration of form and character - help landscape treatments integrate through use of forms and treatments reflective of the character of that area - pursue solutions that ensure liveability and continued use of land surrounding the corridor by minimising visual impacts and noise effects, and maintaining local accessibility.
6.6 Bridges
The bridges for the Northern Connector would be designed in accordance with Australian Standard AS5100 Set–2007: Bridge design and the adopted urban design principles (see Section 6.5.3).
6.7 Surface water drainage
The scope of works for the Northern Connector stormwater design will: . ensure the project drainage system provides for the existing or required flood protection standard on the natural and constructed drainage systems crossed by the project and any other future Council proposals to upgrade these systems . design drainage systems for both minor (5-year average recurrence interval (ARI)) and major (100-year ARI) flood events . design waterway openings to protect the project from flooding and cause minimal disruption to existing drainage systems for both minor and major flood events . ensure the drainage strategy diverts stormwater off and away from the project itself, meets specified standards and has minimal impact on downstream drainage systems . design to provide for the impact of sea level rise on the transport assets and drainage structures and any Coast Protection Board requirements.
6.8 Lighting
Road lighting will be designed in accordance with AS/NZS 1158 Set–2007: Lighting for roads and public spaces and generally only be provided at interchanges. This standard permits the State road authority, in this case DTEI, to make the final determination on light installation on low traffic volume roads.
No lighting will be provided in the rail corridor.
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The lighting design principles include: . use of energy-efficient lamps and equipment where possible (e.g. light-emitting diode lamps) . use of road safety devices (e.g. high visibility edge line markings, retro- reflective materials) to minimise need for lighting . appropriate levels of lighting . specially designed luminaries and installation geometry to minimise sky glow and effects on residences. The lighting layout will be designed by the design engineers and urban designers in accordance with the urban design framework (see Section 6.5).
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80 Northern Connector Project Impact Report Chapter 7 – Development of the Northern Connector project
7 Development of the Northern Connector project
Alternative road and rail corridors were investigated during the selection of the proposed integrated road and rail transport corridor.
7.1 ‘No Northern Connector’ option
7.1.1 Road
Should the Northern Connector not be built, traffic volumes on Port Wakefield Road and Salisbury Highway, in particular, as well as Main North Road and some arterial and local connecting roads (including Kings Road, Bolivar Road and Martins Road), will increase significantly and result in: . increased traffic congestion and delays . reduced access to adjacent businesses and local neighbourhoods . more road crashes . reduced efficiency for freight transport through the area . increased environmental effects — noise, air quality, water quality . reduced economic benefits/development.
In this case, sections of Port Wakefield Road, Salisbury Highway and Main North Road would require substantial upgrading and widening to support forecast traffic volumes, and efficient and safe transport. Some sections of these roads could not feasibly be upgraded to expressway standard because of the high social and environmental impacts of: . land acquisition . reduced community accessibility . increased noise . high construction costs. Roadside residential and commercial properties would be significantly affected by upgrades to Port Wakefield Road, between Waterloo Corner and the Greenfields wetlands, and Main North Road, between Gawler and Mawson Lakes.
Salisbury Highway, between Port Wakefield Road and South Road, would need to be widened substantially by at least two lanes in each direction by 2031. This would significantly affect the Greenfields and Barker Inlet wetlands along both sides of the road. The Salisbury Highway–Port Wakefield Road interchange would also require upgrades to allow higher volumes of southbound traffic.
These road upgrades would not provide the same levels of service as an expressway nor meet the required national transport objectives.
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A number of other arterial roads in the project area would also need to be upgraded to improve safety and access: sections of Kings Road and Waterloo Corner Road, between Port Wakefield Road and Salisbury Highway. Changes to the local road network could be expected with increased development: . upgrading of Wyatt Road to a divided four-lane road (two lanes in each direction), to service the rapidly growing Edinburgh Parks development (approximately 22,000 vehicles per day) . upgrade of Bolivar Road, between Port Wakefield Road and Kings Road, to four lanes, including upgrades to the Bolivar Road–Kings Road intersection, due to increased traffic . upgrades to Kings Road, between Bolivar Road and Salisbury Highway, to cater for forecast traffic demands (approximately 15,000 vehicles per day) . additional lanes on Martins Road, between Kings Road and Port Wakefield Road, due to forecasts of up to 35,000 vehicles per day. The secondary economic benefits from increased development and employment opportunities (see Section 5.3) would be foregone without the project. The additional traffic congestion could produce a net negative economic result through increased travel costs and making the area unattractive to additional development.
7.1.2 Rail
The existing 19 km rail freight corridor between Virginia and Port Adelaide currently has 12 level crossings. Without the new Northern Connector rail line, efficiency of rail operations, particularly for freight movement, would fall through increased travel times and travel costs. Safety risks would increase at railway level crossings with increased train and vehicle traffic. Some level crossings, particularly between Dry Creek and Port Adelaide, will require future grade-separation of local traffic from the rail freight. Therefore, without the rail component of the project there will be: . continued traffic congestion at rail crossings . reduced transport efficiency . increased travel costs . continued reduction of social and environmental conditions . continuing reduction of road and rail safety along the existing rail freight line from Virginia to Port Adelaide . reduced and constrained economic development.
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7.2 Development of the Northern Connector project
A number of environmental, social, economic and engineering assessments and investigations have been undertaken to determine the appropriate location and extent of the Northern Connector Project.
Preliminary planning assessments, before 2008, investigated a number of options including the upgrading of Port Wakefield Road to expressway standard and development of a new road corridor for a future expressway to the west of Port Wakefield Road between the Northern Expressway and Salisbury Highway. No provisions were made for a new rail line at that time.
These options were assessed based on a review of: . service (electricity, gas, telecommunications) issues . social and environmental impacts . traffic impacts . costs . economic benefits. The conclusion was a preference — for engineering, social and economic reasons — for the Western Alignment Option (a road corridor to the west of Port Wakefield Road), as opposed to the upgrading of Port Wakefield Road to expressway standards. Following an engineering and environmental workshop, this route was further refined and modified to accommodate updated demographic forecasts and traffic modelling, requiring the project to be extended to include upgrades to sections of Salisbury Highway, which would otherwise act as critical road network capacity constraints. Following this assessment, the project scope was modified to include two rail tracks within the median (centre) of the Northern Connector road corridor. The road and rail options were progressively developed, taking into account: . preliminary investigations . relevant social, physical and environmental constraints and opportunities of the project area . community feedback . design criteria.
A reference concept for the road–rail corridor was developed identifying the proposed corridor location in the Central and Southern project sections (Section 1.1.1) and an area in the project’s Northern section where further investigation was required to determine the preferred location. Potential road interchange locations were also identified for further investigation.
The Strategic Road/Rail Link Planning Study together with the road–rail reference concept was publicly announced by the Minister for Transport in 2008 to enable the
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community and stakeholders, including local councils and affected landowners, to assess it and comment.
7.3 Road route development — options considered
The information gathered from the community, and from further investigations on traffic volumes, engineering, safety and environmental issues, led to the development of three to four corridor options in each of the three project sections (Northern, Central and Southern) (Figure 1.2). The preliminary design of each option was in line with the planning and design principles and standards identified in Chapter 6. The Southern section of the reference concept was significantly changed to link more directly to the Port River Expressway and South Road interchange. The change came about after it was determined that a 3 km upgrade of the existing Salisbury Highway would be required to meet safety and performance objectives without substantial widening (significantly impacting on the adjacent Greenfield Stage 3 wetlands, State Heritage Listed Magazine Bunkers and Barker Inlet north and south wetlands). The new concept would also reduce impacts on the operation of the Cheetham Salt Ltd Dry Creek salt fields. The scope of the project was subsequently changed to include additional lanes of traffic in each direction. The revised reference concept formed the basis for developing and comparing alternative route options. A broad list of road–rail route options, and the no Northern Connector option (Section 7.1), were considered and reduced to a smaller set of alternative road–rail route options. This set of 11 options was presented at an innovations workshop in 2008 where key stakeholders assessed them. Each route option was contained wholly within one of the three sections: three in the Northern section, four in the Central section and four in the Southern section (Figure 7.1)
7.3.1 Selection of preferred road route
A weighted multi-criteria evaluation matrix technique was adopted to assess the relative benefits and impacts of each of the short-listed options. The assessment compared route corridor options against the relevant base case (reference concept): Option 1A, 2A or 3A (Figure 7.1).
Assessment criteria The assessment criteria (Table 7.1) were based on the project objectives (Section 1.2) and helped differentiate between options. Weightings (Table 7.1) were agreed, based on the significance of the criteria in each project section.
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DAYSRD WEST LAKES SHORE Option 3A Option 2A Option 1A Option A Interchange locationROYAL PARK Option 3B Option 2B Option 1B Option B NB: colours of interchange circle corresponds to the colour of its Option 3C Option 2C Option 1C Option C option(s) Option 3D Option 2D Option D Northern Connector Project Impact Report Chapter 7 – Development of the Northern Connector project
Table 7.1 Assessment criteria Weighting by project section Criteria Northern Central Southern Estimated construction cost 15 15 15 Accessibility 15 10 10 Functionality 15 15 15 Operations and maintenance 5 5 5 Social/amenity 15 20 10 Property acquisition 10 10 10 Environmental 10 15 20 Landuse and zoning 15 10 15 Total criteria weighting 100 100 100
Route assessment workshop Key project stakeholders at the 2008 assessment workshop were: . Department for Transport, Energy and Infrastructure: Infrastructure Division; Metropolitan Region; Public Transport Division; Policy and Planning Division . Department for Environment and Heritage . Department of Water, Land and Biodiversity Conservation . SA Water . Department of Planning and Local Government . Coast Protection Board . Australian Rail Track Corporation . Department of Trade and Economic Development . Department of Primary Industries and Resources . City of Playford . City of Port Adelaide Enfield . City of Salisbury . technical specialists from environmental and engineering consultancies, including a wetlands designer and a flora and fauna expert.
Figure 7.1 shows the route corridor options in the Northern, Central and Southern sections assessed during the workshop. Attendees rated each option against the base case (route Options 1A, 2A and 3A) and recorded comments and possible strategies to further mitigate impacts. The ratings were entered into a spreadsheet evaluation model to calculate overall weighted scores.
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The environmental weightings were then increased over the engineering weightings to test the robustness of the outcomes. Cost was given a weighting of zero. These adjustments did not change the overall rankings, suggesting that the assessment and preferred road route selection process were robust.
Table 7.2 identifies the road corridor route preferred following the assessment at the workshop (see Figure 7.1)
Table 7.2. Preferred road corridor route following route assessment workshop Project section Preferred road corridor option* Northern 1A Central 2D Southern 3B
* Figure 7.1
In late 2008, using the criteria in Table 7.1, interchange layouts were also assessed and shortlisted for the locations: . Northern interchange (Northern Expressway–Port Wakefield Road) . Waterloo Corner interchange . Bolivar Road interchange . Globe Derby Park interchange . Southern interchange (Port River Expressway–South Road).
7.4 Rail route development — options considered
The rail line was originally proposed as a dual rail line in the median of the road carriageways that connected to the existing rail freight line at Kings Road, Virginia and the Outer Harbor line turnout at Dry Creek south rail yards.
7.4.1 Selection of the preferred rail route
A rail line between the road carriageways in the Northern and Central sections directly relates to the selected road route. A number of rail routes in the project’s Southern section were also developed and assessed at the 2008 workshop using the assessment criteria and process identified in Section 7.3.1.
The four rail options (A, B, C and D) assessed were designed to coincide (and be interchangeable) with at least one of the four road route options (3A, 3B, 3C and 3D) in the project’s Southern section (Figure 7.1). Rail Option B (coinciding with Road Option 3B) was selected as the preferred rail route at that time.
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7.5 Amendments to the preferred road and rail route – leading to the proposed road and rail route
The preferred (selected) road and rail route was announced by the Minister for Transport in July 2009, to enable further community input to the planning process.
Following this announcement, detailed environmental, social, economic and engineering investigations resulted in amendments/modifications to the road and rail route and interchange layouts.
7.5.1 Road and interchange modifications
The following road and interchange modifications were made to the preferred road route.
Entire length . Reduction from four lanes in each direction to three lanes in each direction. Upon further analysis and assessment it was determined that three lanes in each direction provides adequate functionality to meet the needs of long distance trips whilst Port Wakefield Road will provide for efficient movement of local trips. The corridor width will allow for further road widening/upgrades when required in the future
Central section . Route shifted further to the east through the SA Water Bolivar site to increase buffer distance to the wastewater treatment plant and avoid the SEAGas main
Southern section . Globe Derby Park interchange removed from the scope of the project following further investigation and release of The 30-Year Plan for Greater Adelaide (Department of Planning and Local Government 2010a), which identified Cheetham Salt Ltd Dry Creek salt fields as a future urban expansion area; provision for future construction of the interchange has been allowed should it be required . Route shifted further west to reduce the impact on operations of the Cheetham Salt Ltd Dry Creek salt fields . Layout of Southern interchange modified to reduce impacts on Wingfield landfill and minimise the footprint (area) of the interchange in Barker Inlet north wetlands while still providing a safe and functional interchange
7.5.2 Rail modifications
The following rail modifications were made to the preferred rail route.
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Entire length . reduction from dual rail line to single rail line with two passing loops; corridor width will allow for further rail line/passing loop additions if later required . Relocation and redesign of the rail line from the median to the western side of the road carriageways following reassessment of its connection with existing rail infrastructure in Dry Creek area and environmental impacts associated with traversing the Greenfields Stage 3 wetland (Figure 7.2)
Southern section Following additional environmental investigations coinciding with the release of the 30-Year Plan, which identified the Dry Creek salt fields as a future urban expansion area, the rail route in the Southern section was relocated to the western side of the road carriageways for the following benefits over the previous rail route (Figure 7.2): . Western rail corridor acting as a sea wall (to Coast Protection Board requirements) for the eastern Northern Connector road and developments (also reduces height and fill requirements for the road component) . more direct connection to the Port Adelaide rail freight line . more direct connection to the Adelaide rail freight line . unlocks commercial and industrial development opportunities along the corridor, including the Economic Development Precinct in Gillman and Defence SA in Port Adelaide . avoids directly impacting the Greenfields Stage 3 wetlands and the threatened birds and their habitats in the wetland . minimises impacts on the operation of the Dry Creek salt fields (previous option bisected the salt fields) . maximises land available for possible urban expansion area in Dry Creek salt fields (previous option bisected the salt fields).
7.6 Northern Connector integrated road and rail transport corridor – proposed route
The rigorous road and rail route development and selection process outlined above has identified the proposed route for the Northern Connector Integrated Road and Rail Transport Corridor (Figure 1.2).
Details of the project, the corridor and the reference design in Chapter 8 and Figures 8.3 a, b and c show the transport corridor selected for detailed environmental, social, economic and engineering assessments (Volume Two of the Project Impact Report).
Throughout the design phase of the project, modifications to the road route, rail route and interchange layouts will continue to be investigated and, where feasible, adopted in response to community feedback, engineering, safety, social,
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environmental and economic considerations. Any modifications requiring additional investigations and assessment will be presented in the Supplement Report.
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92 Northern Connector Project Impact Report Chapter 8 – Project description
8 Project description
8.1 Overview
The Northern Connector reference design has been developed in response to design criteria, community feedback on the concept scheme, and outcomes of environmental, social, economic and engineering investigations. It also satisfies the project objectives (Section 1.2) and design principles and standards (Chapter 6). The project has the following key features: . a new road (15.6 km), three lanes in each direction, between the Northern Expressway and the South Road–Port River Expressway junction . four road interchanges: - Northern interchange - Waterloo Corner interchange - Bolivar interchange (on-ramp) - Southern interchange . 1-in-100 year flood immunity . wide median and outer roadside shoulders . a system of swales and detention basins to receive and, where appropriate, detain stormwater . Port Wakefield Road–Waterloo Corner and Port Wakefield Road–Bolivar Road intersection upgrades to connect to Northern Connector interchange ramps . approximately 30.9 kilometres of standard gauge, single-track freight rail line and a maintenance/access track, generally located to the west of the road carriageways . two 2 km passing loops at Gillman and north of Waterloo Corner interchange . four rail bridges separating rail freight from road traffic . a shared-use (pedestrian and cyclist) path . Barker Inlet north wetland modifications . wetland offset or rehabilitation areas (for flood storage, water quality treatment and habitat) . swale drains and detention basins . landscaping.
8.2 Establishing the corridor
The Northern Connector corridor would generally be 120 m wide and accommodate the two road carriageways, rail line and shared-use path, together with road
93 Northern Connector Project Impact Report Chapter 8 – Project description
embankments, landscaping, water quality control measures, fencing and other environmental mitigation measures. The corridor boundary is shown in Figure 8.1. Land within this corridor would be acquired in accordance with the Department for Transport, Energy and Infrastructure standard acquisition process under the Land Acquisition Act 1969. Further information on property acquisitions and property impacts can be found in Chapter 13.
8.3 Corridor details
The corridor cross-section (Figure 8.2a-b) is typically 120 m wide. It would consist of two separated three-lane road carriageways, with a 20 m wide rail corridor generally located to the west of the road carriageways. A shared-use path for pedestrians and cyclists will also be provided within the corridor. The remainder of the corridor width would be taken up with drainage swales, batter slopes, buffer zones and, where applicable, landscape plantings. The width of the corridor also allows for future widening of the road and duplication of the rail line should it be required. In the Southern section, where the rail line separates from the road carriageways, the rail corridor would be 20 m wide.
8.3.1 Road Horizontal alignment The concept design of the Northern Connector road carriageways (Figures 8.3a–c) shows the Northern Connector road starting at the intersection between Port Wakefield Road and the Northern Expressway in Virginia and proceeding south, parallel to the existing Port Wakefield Road for approximately 8 km through largely horticultural land to Bolivar. The corridor would pass across and close: . Curnow Road . Symes Road . Anjanto Road . St Kilda Road . Undo Road . Summer Road . Hodgson Road.
Further details on local access are provided in Chapter 15.
The Northern Connector road corridor would then run inside Bolivar Wastewater Treatment Plant (WWTP; along the plant’s eastern boundary), across Little Para River and to the west of the suburb of Globe Derby. South of Globe Derby Park (within the Dry Creek salt fields), the alignment would adopt a more south-westerly
94 OLD PORT WAKEFIELD RD GAWLER! PENFIELD RD
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Figure 8.2a Typical corridor cross-section north of Dry Creek salt fields (Northern and Central sections)
Figure 8.2b Typical corridor cross-section in Dry Creek salt fields (Southern section)
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Northern Connector boundary Embankment Northern Connector Project Impact Report Chapter 8 – Project description
course, to eventually tie in with the existing South Road, Port River Expressway and Salisbury Highway interchange at Wingfield (Figure 8.3c). The southern-most 6 km of the route, would lie almost entirely on existing salt crystallisation pans and concentrator ponds of the Cheetham Salt Ltd Dry Creek salt fields. The final 1 km would traverse North Arm Creek mangroves and Barker Inlet north wetlands.
Vertical alignment The Northern Connector road carriageways are situated on typically flat and low- lying terrain. The westerly rail corridor will act as a sea wall for the road component, thereby reducing the height of the road and fill required to construct the road. The typical and minimum required road level for flood immunity is 3.15 m Australian height datum (AHD). Thus, the required typical embankment would range between 1 m and 3.5 m in height. The Northern Connector road would typically remain at grade, with local roads being elevated over it. North of Dry Creek salt fields, the road would be on a shallow fill embankment approximately 1–1.5 m above ground level. South of this point (through the salt fields to the Southern interchange) the embankment would be approximately 3.5– 4 m above ground level, as it traverses the low-lying Cheetham Salt Ltd Dry Creek salt fields. High embankments of the order of 9–12 m above ground level would be required at: . ramps at the Northern interchange (Figure 8.3a) . an overpass at the Waterloo Corner interchange (Figure 8.3b) . Southern interchange (Figure 8.3c).
8.3.2 Rail
Horizontal alignment East of Port Wakefield Road at Virginia, the standard-gauge rail line would start at a new turn-out from the existing freight rail line at Virginia, around 2 km north-east of the Northern interchange (Figure 8.3a). A new spur line connection to the proposed road–rail intermodal at Direk will also be provided. The existing King Road level crossing will be realigned to allow connection with the existing rail line.
Travelling south, the rail line will pass under the existing Port Wakefield Road– Northern Expressway bridge (i.e. the Northern interchange) to the north of the Northern Expressway road carriageways. It would continue to the west of the road carriageways for the next 3 km where it bypasses around the Waterloo Corner interchange, being overpassed by the local road. The rail then essentially follows the road alignment and runs within Bolivar WWTP (along the plant’s eastern boundary), across Little Para River and to the west of the suburb of Globe Derby just north of Dry Creek salt fields (Figure 8.3b–c).
100 Northern Connector Project Impact Report Chapter 8 – Project description
In the project’s Southern section the rail line (Figure 8.3c) separates from the road carriageway as it enters Dry Creek salt fields allowing for a future Globe Derby Park interchange (if required). The rail line then separates into two lines: . travelling south, over the Northern Connector road carriageways via an overpass, then back to ground level, running immediately adjacent to Barker Inlet north wetlands and then via another overpass (embankments and bridge structure) over Salisbury Highway returning to ground level in Barker Inlet south wetlands creating a North–South rail link for freight trains travelling from Melbourne to Perth via Adelaide . travelling west, across North Arm Creek, adjacent to the existing sea wall through the Gillman area then heading south to connect with the existing freight rail line to Port Adelaide and new spur line to Port Flat siding, to be constructed. The rail corridor in the Southern section is approximately 20 m wide Two rail passing loops (i.e. double tracks), both of approximately 2.1 km length, will be constructed at Gillman and north of Waterloo Corner interchange. Vertical alignment The Northern Connector rail line will be situated in typically flat, low-lying terrain. The rail line and ballast will sit on an embankment formation of 1.0–4.1 m in height. In the Southern section the rail embankment height will be higher than the road embankment height allowing for use of the rail embankment as a sea wall. The rail line will pass over the Northern Connector road carriageways and the Salisbury Highway in the project’s Southern section.
8.3.3 Shared-use path
A 3 m wide shared-use path (Figure 8.2) will be provided along the corridor connecting the shared used path along the Northern Expressway to the cycle/pedestrian facilities planned as part of the South Road Superway project. It will be located generally to the east of the road carriageways, and safely separate pedestrian and cycling activities from the road carriageways and rail freight line of the Northern Connector. The most appropriate positioning of the shared use path and its connection to the existing pedestrian and cycle paths in the project area (Section 3.4.2) will be determined during the detailed design phase.
8.4 Interchanges
Interchanges will allow motorists to access or exit the expressway at four locations along the Northern Connector: . Northern interchange (Figures 8.3a) . Waterloo Corner interchange (Figure 8.3a) . Bolivar interchange (Figure 8.3b) . Southern interchange (Figures 8.3c).
101 Northern Connector Project Impact Report Chapter 8 – Project description
Provision in the corridor has been made for future construction of a Globe Derby Park interchange (see Section 8.4.4) should it be required for the proposed urban expansion in Dry Creek salt fields identified by The 30-Year Plan for Greater Adelaide (Department of Planning and Local Government 2010a).
8.4.1 Northern interchange
The Northern interchange (Figure 8.4) will be located in Virginia, where the Northern Connector will intersect Port Wakefield Road and join the Northern Expressway. The main through route (direct and high speed) will be between the Northern Expressway and Northern Connector for vehicles travelling to or from Gawler along the existing bridge at the Northern Expressway–Port Wakefield Road intersection. The existing road layout will be modified by extending the traffic travelling to and from the Northern Expressway through the central and south spans (openings) of the existing bridge with the freight rail line using the northern-most span.
In addition, the Northern interchange will: . provide a northbound off-ramp from the Northern Connector to Port Wakefield Road for vehicles travelling north to Port Wakefield and beyond . provide a southbound on-ramp from Port Wakefield Road to the Northern Connector for vehicles travelling towards Adelaide . allow vehicles travelling north and south along Port Wakefield Road to continue using the existing overpass bridge . retain the southbound off-ramp from the Northern Expressway to Port Wakefield Road. Motorists travelling south from Port Wakefield Road, north of the Northern interchange, and from the Northern Expressway wanting access to Port Wakefield Road and the local road network (including Waterloo Corner Road and Bolivar Road) between this interchange and Salisbury Highway will not access the Northern Connector but continue along Port Wakefield Road.
8.4.2 Waterloo Corner interchange
The Waterloo Corner interchange, in the suburb of Waterloo Corner, would connect the Northern Connector with Waterloo Corner Road (Figure 8.5). Figure 8.6 shows an artist’s impression of the concept design.
The interchange has been designed for consistency with the layout of interchanges along the Northern Expressway. Waterloo Corner Road will be extended from Port Wakefield Road to Robinson Road to allow for construction of the interchange. The existing signalised Waterloo Corner T-intersection with Port Wakefield Road will be upgraded to a signalised four-way intersection.
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The Waterloo Corner interchange will provide a: . northbound off-ramp from the Northern Connector to the new Waterloo Corner Road extension for vehicles access to Robinson Road, St Kilda, Port Wakefield Road and Waterloo Corner Road . northbound on-ramp to the Northern Connector for vehicles coming from Robinson Road, St Kilda, Port Wakefield Road and Waterloo Corner Road . southbound on-ramp to the Northern Connector for vehicles travelling from Port Wakefield Road and Waterloo Corner Road and Robinson Road. Southbound vehicles needing to access Waterloo Corner Road or Robinson Road will need to access Port Wakefield Road at the Northern interchange. Traffic from Robinson Road (and the local road network to the west of the Northern Connector) will have full access to Port Wakefield Road via an overpass at Waterloo Corner interchange. The on-ramps and off-ramps at this interchange will all be single lanes.
Figure 8.6 Waterloo Corner interchange looking north (rail line to the west) (artist’ s impression, concept only)
105 Northern Connector Project Impact Report Chapter 8 – Project description
8.4.3 Bolivar interchange
The Bolivar interchange will be located in the suburb of Bolivar at the Northern Connector intersection with Bolivar Road (Figure 8.7). It provides a single-laned on- ramp for southbound traffic from Port Wakefield Road and Bolivar Road on to the Northern Connector.
Southbound vehicles needing to access Bolivar Road or Port Wakefield Road to Salisbury Highway will need to access Port Wakefield Road at the Northern interchange. Motorists wanting to access Bolivar Road and Port Wakefield Road will need to travel from Salisbury Highway along Port Wakefield Road or exit at the Waterloo Corner interchange. The 30-Year Plan for Greater Adelaide (Department of Planning and Local Government 2010a) identified potential growth area in the suburbs of Bolivar. The road corridor has allowed for possible future construction of a northbound off-ramp from the Northern Connector to Port Wakefield Road and Bolivar Road to accommodate this potential growth area (Figure 8.7). The construction of this off ramp is not part of the current project scope and if required, would be constructed post 2031.
8.4.4 Possible future Globe Derby Park interchange
The 30-Year Plan for Greater Adelaide (Department of Planning and Local Government 2010a) identified a potential growth area in the suburbs of Dry Creek/Globe Derby Park within the existing Cheetham Salt Ltd salt fields. Provision in the corridor has been made for future construction of a Globe Derby Park interchange should the proposed urban expansion on the salt fields go ahead. (Figure 8.8). The construction of the interchange is not included in the current project scope.
8.4.5 Southern interchange
The Southern interchange, located in the suburb of Wingfield within Barker Inlet north wetlands, would connect the Northern Connector with South Road, the Port River Expressway and Salisbury Highway (Figure 8.9). It has been designed to ensure compatibility with the South Road Superway project. This directional system interchange will provide: . for northbound and southbound traffic flow to and from the Northern Connector and South Road Superway . a westbound off-ramp from the Northern Connector to the Port River Expressway . a north bound on-ramp from the Port River Expressway to the Northern Connector
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. an east bound ramp from the South Road Superway to the Salisbury Highway . a southbound ramp from the Salisbury Highway to the South Road Superway. There is potential for the existing South Road ‘loop’ to and from the Salisbury Highway to be rehabilitated back to a wetland environment; its movement will be replaced by the east and south bound ramps identified above. These new ramps will allow for safer high speed travel in this complex system interchange. The wetland area between these ramps and Salisbury Highway would be retained and connected to the surrounding wetlands. The interchange has been designed to minimise the impact to the south-east corner of Wingfield landfill. The interchange layout is currently being reviewed to further reduce the impact on the landfill.
The southern interchange would be built using a combination of embankments and structures (bridges, culverts). The wetland would require some modification to ensure continued flow and habitat connectivity within it (Section 8.13.2).
8.5 Structures
Structures on the Northern Connector, such as bridges and culverts, have been designed to meet specific functional requirements. The designs are indicative and would be further refined during the detailed design phase.
8.5.1 Interchange bridges
The location of interchange bridges is shown in Figures 8.4, 8.7 and 8.9. A typical access interchange bridge will consist of a cross-road overpass spanning the Northern Connector. Five spans, typically of 1.5–8 m deep precast concrete beams, will be required. Piers will be solid concrete wall elements. Bridges will be designed using the urban design principles identified in Section 6.5.3.
8.5.2 Road bridges — crossing the rail corridor
Only one road bridge over the rail line is required, at the Waterloo Corner interchange (Figure 8.5).
8.5.3 Rail bridges
Rail bridges are required to carry the freight rail line over: . the Northern Connector road corridor just north of North Arm Creek (Figure 8.3c) . Salisbury Highway (Figure 8.3c).
110 Northern Connector Project Impact Report Chapter 8 – Project description
8.5.4 Watercourse/stormwater control crossings
Watercourse crossings (Figure 8.10) will require bridge or culvert structures at: . Helps Road drain . Little Para overflow . Little Para River . Dry Creek . North Arm Creek (road and rail) . Magazine Creek . Barker Inlet north wetlands . Barker Inlet south wetlands.
The exact form of these structures is yet to be determined. It is expected that most will be relatively minor, generally box culverts or short span concrete plank bridges.
However, over North Arm Creek a combination of embankments, longer bridge structures and culverts will be needed to minimise the impact on mangroves and allow continued tidal flow to mangroves to the east of the Northern Connector rail and road crossings.
8.6 Road pavement
The design of the road pavement (e.g. asphalt) will be determined during detailed design phase. It expected to be full depth, heavy duty asphalt pavement maximising design life and allowing for ongoing use of the road by heavy freight vehicles. Low noise road-surface treatments, such as stone mastic asphalt, would be used.
8.7 Emergency lay-by areas
The outer shoulder widths (3 m) on the Northern Connector (Figure 8.2) would enable most vehicles to pull over at any location in the event of a sudden breakdown or minor accident, to retain clearance for through traffic.
8.8 Lighting, fencing and signage
The road and rail corridor would generally be unlit. However, all interchanges and the main intersections with Port Wakefield Road will have lighting designed according to AS/NZS 1158 Set–2007: Lighting for roads and public spaces. In all cases where technically and economically feasible, the most energy efficient lighting technology will be used.
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Fencing along the Northern Connector corridor will be rural type (stock) fencing.
Road signage will be determined during the detailed design phase. Discussions with the relevant councils will determine particular signage requirements. Signage would include intelligent transport systems, large overhead gantries and ground mounted signs. Typical road signs would indicate: . different destinations before on-ramps or off-ramps . speed signs . stop signs . lane markings . river names . cross road names.
8.9 Emergency vehicle access
Emergency vehicle access to and across the Northern Connector road will be provided at Waterloo Corner interchange. Limited access will also be possible at both Northern and Southern interchanges. In addition, various locations along the length of the road corridor will have turn- around facilities for emergency vehicles. The optimal locations of these facilities will be determined following more detailed discussions with emergency services organisations during the detailed design phase.
8.10 Stormwater, drainage and water quality
For the purposes of stormwater, drainage and water quality management, the project area has been divided into six subsections (Figures 20.4 and 20.5): . Northern interchange–St Kilda Road section . Helps Road drain section — from St Kilda Road to the southern edge of Bolivar WWTP effluent ponds (defined by the boundary of Helps Road drain catchment) . Little Para River section — from the southern edge of Bolivar WWTP effluent ponds to mid-way between Little Para River and Dry Creek (defined by the boundary of Little Para River catchment) . Dry Creek section — from mid-way between Little Para River and Dry Creek to the salt crystallisation pan about 700 m south of Dry Creek . Cheetham Salt Ltd Dry Creek salt fields section . Southern interchange wetlands section. Flooding and drainage design for each subsection is discussed in detail in Section 20.4.
113 Northern Connector Project Impact Report Chapter 8 – Project description
8.10.1 Northern interchange–St Kilda Road section
A drain system constructed in the Northern Connector corridor would consist of ponds, open channels or vegetated swales and cross culverts (see Section 20.4). No drainage systems would be provided on St Kilda Road, outside the project corridor.
8.10.2 Helps Road drain section
The cross drains (culverts) under Port Wakefield Road are of a Q100 standard and the same hydraulic capacity is expected to be adopted for crossing the Northern Connector. A box culvert structure would be installed over Helps Road drain (Figure 8.10).
8.10.3 Little Para River section
The embankment of the Northern Connector in this section would intersect and join existing seawalls. The higher Northern Connector embankment would play a dominant role in the tidal and flood protection function of the area. In addition, new culverts with non-return flaps would be constructed where roadside swales intersect with existing embankments.
In 2004–05 the City of Salisbury completed construction of the Little Para diversion weir and overflow drain. This drain diverts all flows in excess of 30 m3/s through a separate drain, which flows under Port Wakefield Road and out towards the Bolivar flood gap. The main Little Para River channel is leveed to the 30 m3/s capacity for its entire length between the overflow drain and Port Wakefield Road.
The current capacities of the Little Para River and Little Para overflow drain crossings at Port Wakefield Road are Q100 standard approximate for peak flows of 30 m3/s and 26 m3/s respectively. Hydraulic capacity of a similar order would be adopted at crossings of the two watercourses by the Northern Connector. Box culvert structures would be installed over Little Para River and Little Para overflow drain (Figure 8.10).
8.10.4 Dry Creek section
The Northern Connector would be on low-lying land to the north of the Dry Creek levee. The adjacent built-up corner of the suburb of Globe Derby Park is on even lower land and is currently drained with a pump system (discharging to Dry Creek). Flooding risk is high in this area, evident from City of Salisbury flood maps, which indicate a flood of 1 m deep under Q100 conditions. The Northern Connector would adopt the most appropriate engineering approach to maintain the magnitude of the flood to existing levels, probably a Q100 standard similar to that at Port Wakefield Road.
114 Northern Connector Project Impact Report Chapter 8 – Project description
Dry Creek, at its intersection with the Northern Connector, is bounded by levees on both sides. The Northern Connector embankment would match and join with the existing levees. Side swales would have to discharge to Dry Creek via culverts with non-return flaps, through the levees. During high tides, adequate storage upstream of the culvert in the side swale will ensure that spillage of side drains does not affect the built-up areas 500 m to the east. Non-saline runoff from the Northern Connector embankment on the short section through Cheetham Salt Ltd Dry Creek salt fields would drain into Dry Creek. Design would ensure that any super-saline runoff was not discharged to the creek.
A number of sections of Dry Creek have been recently upgraded to Q100 standard.
8.10.5 Cheetham Salt Ltd Dry Creek salt fields section
The flat terrain in the middle of the salt fields south of the Dry Creek section makes it difficult to form graded side swales. Due to its distance from watercourses (Dry Creek and Barker Inlet), runoff from this section is likely to become super-saline and therefore not suited for disposal to receiving watercourses. Road runoff would have to be discharged to detention basins or evaporating ponds with appropriate storage capacity. Cross culverts would be required under the Northern Connector to avoid excessive water build-up to one side of the embankment (subject to further discussions with Cheetham Salt Ltd).
8.10.6 Southern interchange section
The Northern Connector road would bisect Barker Inlet wetlands at the Southern interchange. The rail line would bisect Barker Inlet south wetlands. These wetlands provide important water treatment and flood control for the inner northern suburbs of Adelaide. Side swales would be required to collect and treat runoff from road pavement before it could be discharged into the wetlands. The embankment of the Northern Connector would impact a portion of Barker Inlet north and south wetlands, with volumetric storage being offset in Barker Inlet north by wetland modifications for flood mitigation, water quality treatment and environmental characteristics, such as habitat (see Section 8.13).
8.11 Services
Typical services or utilities are water pipelines, sewer or gas lines, overhead or underground electrical conductors, and telephone cabling. Existing services that cross the Northern Connector corridor for the length of this project were identified through a ‘Dial Before You Dig’ search and consultation with relevant authorities (Table 8.1). They could be impacted by the project and would need either protection or realignment to ensure continuation of service during construction and operation.
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Table 8.1 Existing services and utilities Utility Authority Gas 300 mm high pressure pipeline SEAGas 508 mm gas main pipeline Epic Energy Water and sewer Bolivar pipeline SA Water 2,625 mm diameter gravity sewer SA Water Stormwater crossings City of Salisbury 125 mm pipeline Cleanaway waste Telstra Optical fibre cables Telstra Overhead power transmission lines High and low voltage cables ETSA 275 kV power lines ElectraNet Others Penrice brine line Penrice Soda Ltd 140 mm diameter Coopers Brewery line Coopers Brewery
Each service would be protected by either a culvert or sleeve pipes as required by the service owner, and specific mitigation measures to existing services: . SEAGas — Service crossings should be perpendicular for cathodic protection of the pipeline. This gas pipeline requires a 0.5 m clearance, otherwise concrete protection should be provided. . ETSA — Crossings of overhead high voltage cables (66 kV) must have vertical safety clearance. . ElectraNet — Vertical clearance of 9.1 m is required between road level and power lines.
8.12 Urban and landscape design
The urban design framework for the project (Section 6.5) will mitigate visual impacts associated with operation of the Northern Connector by appropriate urban design and landscaping (Section 10.4) Landscaping for the project is likely to be concentrated around key locations such as interchanges, consistent with the approach taken on the Northern Expressway. The indicative plant list (Appendix C) includes appropriate plant species for landscaping in saline environments. Landscape and urban treatments will be further developed during the detailed design phase of the project.
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8.13 Wetland impacts and proposed offsets
The project area has a complex combination of sensitive environmental features, large industrial/business operations and communities. Thus, there has been a need to balance many, often competing, environmental, social, economic and engineering issues in planning for the Northern Connector. Construction and operation of the project would have an impact on the constructed Barker Inlet north and south wetland systems (Section 8.13.1). To mitigate this impact a series of proposed offset measures would combine new wetland offset areas, and wetland revegetation and rehabilitation (Section 8.13.2). They would be designed to greatly enhance local and regional biodiversity. Flora and fauna assessment for the project is discussed in Chapter 17 and 18 and the water quality, drainage and flooding assessment in Chapter 20.
8.13.1 Impacts on existing Barker Inlet wetland systems
The constructed Barker Inlet wetlands have three main roles: . flood mitigation and water storage/retention capacity . water quality treatment of stormwater before it enters Gulf St Vincent . a diverse habitat for threatened and non-threatened bird species and other fauna, including threatened and migratory species (the northern wetlands provide freshwater and marine intertidal habitat). Wetlands also favour other activities such as stormwater reuse, and environmental tourism and education. The impacts identified in this section are those associated with the direct (footprint) impacts of construction of the Northern Connector. Potential indirect impacts from the project are discussed in Chapter 18. In addition, the wetlands will require modifications to ensure they continue to function (Section 8.13.2). These areas have not been included at this stage but will be further defined during the detailed design phase of the project. Barker Inlet north wetlands will be impacted by the road component of the project, Barker Inlet south wetlands by the rail corridor (Figure 8.11; Table 8.2). The wetland loss areas identified in Table 8.2 are based on concept design only and will probably be changed and refined during the detailed design phase of the project. Whites Road wetlands will also be impacted but have not been included in Table 8.2.
Table 8.2 Wetland areas impacted by the Northern Connector project, southern section Wetlands Wetland loss (hectares) Marine intertidal (Barker Inlet north) 5.9 Freshwater (Barker Inlet north and south) 11.7 Total 17.6
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Loss areas: Northern Connector road South Road Superway Potential offsets areas, Freshwater wetlands (11.7 Ha) Combination of (loss to offset ratio 1:1.5): Spur line to Port Flat siding Existing railway Mangroves (4.6 Ha) New freshwater / marine intertidal wetlands* Marine intertidal wetlands (5.9 Ha) Wetland modification / rehabilitation Northern Connector rail Existing roads
*Area to be determined Northern Connector Project Impact Report Chapter 8 – Project description
Flood storage (volume) loss in the Barker Inlet wetland system and additional storage volume through modifications to the wetlands will be determined during the detailed design phase of the project.
8.13.2 Wetland modifications, revegetation, rehabilitation and new wetland areas
It is proposed to offset the project impacts to existing wetlands through a combination of modifications, rehabilitation and revegetation to existing wetlands or new wetland offset areas.
The proposed ratio for offset of wetland loss is 1:1.5. That is, offset each 1 ha of direct impacts on wetlands through construction of the project by 1.5 ha of modifications, rehabilitation and revegetation to existing wetlands and new wetland offset areas. Based on loss areas (Table 8.2) a total of 26.4 ha would be offset. The actual wetlands offset/rehabilitation areas will be determined during the detailed design phase following preliminary design and vegetation surveys of the site. The construction of new wetlands and/or modification/rehabilitation of existing wetlands is subject to any necessary approvals under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and Native Vegetation Act 1991.
Modifications and rehabilitation to the Barker Inlet north wetlands Construction of the project will also require modifications to the existing Barker Inlet north wetlands both within and outside of the Northern Connector corridor. Culverts and/or bridge structures will be installed to allow continued flow of water through the wetland systems and works to increase (and offset) the flood storage capacity of the wetland system. These structures will also serve as habitat connections to fragmented areas of the wetlands.
The modifications would look to offset flood storage, water quality and habitat loss in the existing wetlands through construction of the project
The freshwater wetland area lost will likely be offset in an area to the west of the road corridor in the wetlands (Figure 8.11). This area is considered to be poor quality habitat for birds.
Habitat value of the existing Barker Inlet north wetlands could be enhanced by developing additional habitat islands and revegetating some of the poorer quality intertidal areas with targeted landscaping.
Rehabilitation and revegetation of existing wetlands In addition to the modifications and rehabilitation of Barker Inlet north wetlands, rehabilitation works (weed control) and revegetation works could be undertaken the Range and Magazine wetlands. Revegetation works would be based on selecting
119 Northern Connector Project Impact Report Chapter 8 – Project description
specific plant species with a high chance of survival, based on outcomes from other constructed wetlands in the project area (e.g. Barker Inlet north wetlands). The rehabilitation and revegetation works would help improve the biodiversity and habitat value of the wetlands.
New wetland offset areas A number of potential wetland offset areas are currently being investigated (Figure 8.11). New wetland offset areas may consist of marine intertidal and/or freshwater wetlands. Final locations and size are subject to further discussions with the land owner, Land Management Corporation.
Wetlands site 1 — Marine intertidal wetlands Wetlands site 1 (marine intertidal wetlands) is located adjacent to the North Arm Creek mangroves in the Gillman area. Subject to landholder negotiations, it would be constructed to the north of the existing estuary.
The proposed habitat types for wetlands site 1 would replicate those lost though impacts to the Barker Inlet north intertidal wetlands.
The design of wetlands site 1 would allow for inundation by seawater (as tides rise and fall each day) and less frequently (dependent on rainfall) by freshwater from the Range wetlands. Tidal flows would alternately expose and inundate mud flats, which supply feeding habitat for a wide range of waterbirds and shorebirds that currently use Barker Inlet north wetlands (e.g. Latham’s Snipe, Wood Sandpiper, Common Greenshank, Marsh Sandpiper and Broad-billed Sandpiper).
Samphire vegetation planted in the tidal zone would provide suitable foraging habitat for many birds including the Slender-billed Thornbill and the critically endangered (under the EPBC Act) Orange-bellied Parrot, should it continue to survive in the wild. Mangroves might also colonise suitable areas of the wetlands. In addition, the creation of deep open salt-water channels in the intertidal zone adjacent to mangroves or samphire would provide valuable nursery areas for many species of fish (including commercial species).
The advantages of this proposed wetland would include: . being adjacent to and increasing the association with existing marine/mangrove habitats . increasing the availability of marine intertidal habitat in the Adelaide plains region . improving the association with coastal saltmarsh communities to the north . providing a final water quality treatment for stormwater flowing from Range Wetland before discharge to Gulf St Vincent.
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Wetlands sites 2 — Freshwater/Marine intertidal wetlands Wetlands site 2 would be located immediately to the north of the existing Magazine wetlands in Magazine Creek estuary. It could be developed as an extension of the freshwater Magazine Wetland and/or as a marine intertidal wetland through inundation from Magazine Creek estuary.
If a freshwater wetland is feasible then freshwater habitats of reedbeds and sedgeland, similar to those in the Greenfields Stage 3 wetlands, could be designed as habitat for Australian Painted Snipe, Little Bittern, Australasian Bittern, Latham’s Snipe, Spotless Crake, Lewin’s Rail, Glossy Ibis, Australasian Shoveler, Blue-billed Duck, and Brown Quail.
If a marine intertidal wetland is feasible at this location, similar habitats to those identified for wetlands site 1 could be provided.
In addition to the intertidal wetland benefits identified for wetlands site 1, this proposed wetland would have the advantages of: . increased availability of freshwater wetlands habitat in the Adelaide Plains region . increased flood storage capacity of Range wetlands . improvements to the quality of the stormwater discharged into Gulf St Vincent.
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122 Northern Connector Project Impact Report Chapter 9 – Construction and operation
9 Construction and operation
Construction of the Northern Connector (road and rail) would be managed by the Department for Transport, Energy and Infrastructure (DTEI). Once opened, the Northern Connector road would continue to be managed by DTEI and rail would be managed by the Australian Rail Track Corporation (ARTC).
9.1 Construction
9.1.1 Construction activities
Table 9.1 summarises the likely construction phases and activities for the project.
Table 9.1 Summary of likely construction components and activities Component Activity Procurement, award and . tendering environmental . award of contract management system set up . environmental management plans, licences and approvals Site establishment . property adjustments and property acquisition . site set out . site compounds and other ancillary sites . initial environmental safeguards Site preparation . clearing and grubbing . mulching . stripping and stockpiling of topsoil, spoil and unsuitable material . construction access Structures . bridges Earthworks . pre-loading on soft soils . borrow pits . cuttings . fill embankments . select zones . batter treatments Drainage . swales, culverts, pipes . detention basins Interchanges . Northern interchange ramps . Waterloo Corner interchange ramps . Bolivar interchange ramps . Globe Derby Park interchange ramps . Southern interchange ramps
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Component Activity Rail line construction . track works . power works . signalling works Other works . pavement construction . asphalt and concrete batching plants . flora and fauna protection measures . landscaping and wetland construction . noise treatments . safety barriers . accommodation works (e.g. Cheetham Salt Ltd) . lighting, line-marking and signposting Ancillary works . modification/upgrade of local roads . property access . existing expressway works . if required: batching plants, crushing plants, pug mills, stockpile and storage sites Finishing works . remove temporary works . restore and landscape temporary sites . testing and commissioning of railway systems and signals
9.1.2 Project delivery
Indicative timeframes for the project are provided in Table 1.1. The detailed design and construction phase for the project is anticipated to be approximately 36 months. For efficiency, the Northern Connector would be constructed by: . securing and fencing the corridor . constructing temporary haul roads for importing fill material from designated borrow pits . constructing bridges and interchanges concurrently, where possible . accessing and constructing the road from within the corridor as much as possible . constructing the shared-use path concurrently with the road carriageways . constructing the railway formation and maintenance road simultaneously with the road (all permanent railway aspects such as the ballast, sleepers, rails, electrification and signalling would be added by ARTC as soon as the new rail corridor was available) . staging landscaping throughout the construction phase.
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Some aspects of the project may require construction activities outside of normal working hours. Any such works will be undertaken in accordance with DTEI’s Construction Noise and Vibration Operational Instruction to minimise disturbance to local communities.
The likely 36 month design and construction phase would be sequenced as outlined in Table 9.3.
Table 9.3 Indicative design and construction sequence Phase Timing (month number) Detailed design 0–6 Clearing site 0–8 Shifting and protection services 7–10 Earth works 9–21 Drainage culverts 22–26 Bridges 9–35 Pavement layers 22–30 Asphalt surfacing 31–35 Road signage 33–36 Road marking 36 Finishing 36
Possible early works packages may occur to fast track the project. Such works may include accommodation works for Cheetham Salt Ltd (if required) — establishment of replacement crystallisation pans and concentrator ponds, construction of offset wetlands, service relocation and pre-loading of embankments to cater for settlement of soft ground.
9.1.3 Construction methods
Road Construction methods will generally use conventional techniques employed on most major expressway and rail projects, adapted to account for the various engineering (e.g. low strength foundation sub-grade and groundwater) and environmental constraints.
Due to the flat topography, the bulk of the earth works will be on fill. The only cuttings will be for drainage swales adjacent to the road carriageways and for a ramp at the Southern interchange, next to the Port River Expressway (cutting through landfill). The minimal extent of cuttings means that suitable fill material from the corridor is limited.
The extent of the cutting through the landfill will be limited by an appropriate retaining wall erected on the high side of the cutting. Special attention will be taken in this area during detailed design not to compromise landfill stability in any way.
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Construction over wetlands and mangroves in the Southern section will require methods, such as rock end tipping to form a solid base from which to construct the embankment fills, to minimise impacts. The road and rail corridor of the Northern Connector will be formed by an earth embankment founded on the existing ground profile. There are four main foundation conditions and five main embankment heights (Table 9.4).
Table 9.4 Main foundation conditions and embankment heights Foundation condition Location Approximate height of embankment above ground level Pooraka formation Bolivar WWTP and 1 m typically stiff to hard clay northwards Bolivar WWTP and 10 m maximum, for northwards, at-grade approach embankments to separated interchanges bridge overpasses St Kilda formation South of Bolivar WWTP 3.5 m typically soft to stiff clay excluding brine ponds and salt pans Salt crust over possible clay Floors of brine ponds and 3.5 m liner, over St Kilda salt pans south of Bolivar Formation WWTP Fill Bund walls to perimeters of 1 m typically stiff clay and brine ponds and salt pans Penrice grit south of Bolivar WWTP
The varying embankment foundation conditions and embankment heights give rise to varying requirements for foundation preparation and embankment filling.
Embankments — Bolivar Wastewater Treatment Plant and northwards Between the northern extent of the project and Bolivar Wastewater Treatment Plant (WWTP), soil strength is reasonable and embankment height is low, other than at grade-separated interchanges. Conventional embankment construction can, therefore, be adopted: . clear vegetation . strip topsoil . proof roll excavated surface . place and compact embankment fill in layers, with no need for staging of fill construction.
Grade separated interchanges — Bolivar WWTP and northwards At grade-separated interchanges (flyovers) between the northern extent of the project and Bolivar WWTP, the embankments will have a maximum height of 10 m.
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Thus foundation preparation can be undertaken but embankment fill construction may have to be staged. Embankments will be filled to a maximum height of 5 m, with further filling only after a 2–3 month wait to allow the underlying foundation soil to consolidate and gain strength. For embankments that exceed 5 m in height, surcharging of the embankment after it has been filled to full height is recommended. Instrumentation and monitoring of the highest parts of the embankments will also be undertaken.
Embankments — south of Bolivar WWTP, excluding Cheetham Salt Ltd Dry Creek salt fields Soil strength is generally poor south of Bolivar WWTP and the ground surface is submerged in parts (in wetlands). Embankment heights will be greater and their construction will be modified: . strip off surface vegetation and proof roll excavated surface . create a working platform using 0.5–1 m thick shot rock . place and compact embankment fill in lifts, with a maximum of 1–1.5 m embankment height per filling . surcharge the embankment after it has been filled to full height (minimum of 1–1.5 m thickness of fill above the crest level of the full height) embankment to minimise settlement of foundation soil after completion of the road pavement.
Grade separated interchanges — South of Bolivar WWTP South of the Bolivar WWTP, the procedure for preparing foundation and constructing embankments is as described above, except that considerably more filling stages will be required and a considerably longer construction time thus allowed. Geotechnical instrumentation and monitoring of the embankments foundations will also be necessary.
Embankments —Cheetham Salt Ltd Dry Creek salt fields Soil strength at Cheetham Salt Ltd Dry Creek salt fields may be poor, depending on the dryness of the floor. The ground surface would not be expected to be submerged as groundwater should have been excluded from the ponds and pans when they were constructed, by the nature of the perimeter bund construction and any lining of the floor. A modified form of embankment construction will be required: . strip off crust of crystallised salt to expose clay floor lining, or natural soil where clay lining is absent, to remove the risk of embankment settlement caused by long-term dissolution of the salt layer . proof roll excavated surface, where trafficable to construction equipment . for locations where ground is not trafficable to construction equipment, create working platform using 0.5–1 m thick shot rock/rock spalls (coarse gravel/fine
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cobble size rock fragments), which are pushed out and tracked into the in situ ground surface until it tightens up and becomes trafficable . further steps in embankment fill construction as above.
Bund walls to perimeters — Cheetham Salt Ltd Dry Creek concentration ponds The ground surface at Cheetham Salt Ltd Dry Creek concentration ponds is elevated above the surrounding low-lying land. The existing fill that forms the bunds has been in place for many years and is likely to be suitable for incorporation into the embankment in its existing state. The embankment construction will: . remove upper part of bund wall, if required, to achieve formation level . proof roll the surface . place and compact embankment fill in layers over the top surface of the existing bund wall, with no need for staging of fill construction (except for high embankments to grade-separated interchanges), if fill is required to build up to formation level.
Bridges and intersections
Interchanges Typical interchange bridges — flyover structures, elevated over the Northern Connector at-grade road and rail — will be constructed conventionally, by: . stripping topsoil and preparing for pile cap and approach embankment construction . placing fill for embankments in a controlled manner (specialist layered methods would be required for bridges incorporating vertical reinforced earth retaining walls for abutments) . installing piles . constructing pile caps from in situ concrete (some minor dewatering may be required depending on the depth of pile caps and height of watertable) . constructing piers from in situ or precast segmental construction . constructing in situ concrete abutments . placing and aligning bearings . erecting precast concrete beams . pouring in situ concrete topping slabs and approach slabs (where required) . erecting precast concrete barriers and other road furniture.
The long bridges over the wetlands and ramps of the Southern interchange would be similar.
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Rail grade separations The construction of bridges that grade separate road from rail would be similar to that of the interchanges.
Watercourse/stormwater control bridges Culverts would be used for minor structures, constructed conventionally by: . excavating . constructing in situ concrete base . placing precast crown units . backfilling. Some structures would be short-span, plank bridges, constructed in a similar manner to interchange bridges, adapted to a smaller size. The construction methodology for bridges across Barker Inlet north wetlands and North Arm Creek will be determined during the detailed design phase of the project.
Rail The Northern Connector rail track will be constructed from one end to the other. The track, positioned to the west of the two road carriageways on a compacted base, will comprise concrete sleepers on stone ballast with 60 kg/m long welded rails.
Signalling equipment The project includes installation of new signalling equipment to be connected to the existing Advanced Train Running Information Control System control and indications system. Combined service pits located along the length of the railway will facilitate this connection.
Testing and commissioning All aspects of rail operation will be tested, including signalling and communication facilities, train control, the new track and interfaces with the existing network. This work will be undertaken during final track possession.
9.1.4 Equipment, resources and labour
Plant and machinery The plant and equipment likely to be used during construction (Tables 9.5 and 9.6) will be subject to refinement during the detailed design phase.
Materials Construction will require the use of various material types, including: . fill for use in earthworks
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. aggregate for use in concrete batching and pavement . materials for lining drainage channels . sand for use as backfill around pipes . materials for production of cement and asphaltic concretes.
An estimated 3–4 million m3 of bulk fill will be required, mostly for swale embankments. Some will be excavated from adjoining swales.
General fill is likely to be sourced from borrow pits along or near the route (subject to investigations and approvals) with significant balance from commercial sources in the vicinity of the project. Further investigations during the detailed design phase will determine the availability of quality fill. All pavement layer material and concrete aggregate will be sourced from local commercial quarries. Sand for concrete will be sourced from the local commercial sources.
Table 9.5 Equipment likely to be used for most road construction activities Activities Plant and equipment Road: . light vehicles . Construction work sites . fuel storage tanks . Services relocation . concrete and asphalt batch plants . Structures . crushing plants . Earthworks . trucks, cranes and excavators . Structural pavement . elevated platform vehicle . Other roadworks . backhoes . trenchers . small equipment . piling rigs . concrete pumps . barges . bulldozers . scrapers . graders . watercarts . vibratory rollers . drilling equipment . piling rigs . concrete pavers . concrete curing equipment . concrete saws . asphalt pavers . rubber-tyred rollers . bitumen sprayers
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Table 9.6 Equipment likely to be used for most rail construction activities Activities Plant and equipment Rail . crane . Rail signalling . concrete truck . Rail track laying . concrete pump . Overhead signs . concrete agitator . excavator . poker vibrator . rock breaker . compactor . work train . rail grinder . rail dump carts . ballast regulator . tamper . track laying machine . work train . elevated work platform . concrete mixer . pettybone crane
Water use Where possible, water used during construction will be sourced from sustainable supply sources. Construction water will generally be sourced from SA Water, streams, groundwater bores and dams. The proximity to Virginia Pipeline Scheme means that recycled water could be used, subject to an available allocation. The City of Salisbury‘s non-potable water supply from the Greenfields aquifer storage and recovery could also be used. Water will probably be required for: . earthworks construction . dust suppression . watering vegetation . concrete and asphalt batching. A water use and reuse sub-plan will be developed as part of the contractor’s environmental management plan (CEMP) for the project, to ensure the use of recycled water is maximised and waste is minimised.
Other opportunities for sustainable construction Specific considerations to reduce energy use and greenhouse gas emissions during construction could include: . assessing energy efficiency when selecting equipment . maintaining equipment to retain high levels of energy efficiency . using biofuels, where feasible, to reduce greenhouse gas emissions from construction plant and equipment
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. minimising vegetation clearance and replanting where feasible . beneficial reuse of cleared vegetation . using local materials and local staff wherever possible to reduce transport- related emissions . using recycled materials to minimise the lifespan impact of greenhouse gas emissions in production . substituting low greenhouse-intensity materials where appropriate.
Construction workforce The size and composition of the construction workforce would vary depending on the location and construction activities at any given time. Each construction site would require specialist crews, including: . construction management staff . equipment and plant operators . formworkers . steel fixers . concreters . erosion and sediment controls crew . labourers . tradespersons . truck drivers . project managers . designers . lab technicians. The project would provide for an average of 750 direct full-time equivalent (FTE) jobs per year or approximately 3,000 direct FTE jobs over the construction period.
9.1.5 Ancillary construction facilities
Construction work sites, required for personnel, materials and plant, will contain offices, a vehicle parking area, and machinery and plant storage areas. Ancillary construction facilities could consist of: . main compound site . several smaller site compounds . other minor compounds at bridge sites . concrete and asphalt batching plants . crushing operations
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. pug mills . stockpile areas. Potential sites for ancillary construction facilities will be identified and assessed against environmental and engineering criteria (Table 9.7). Work sites will be identified during detailed design and during preparation of the final construction method by the successful contractor. Batching plants may be required for production of concrete and asphalt during construction. They will be located in major work sites, away from sensitive receivers, where possible. Any approvals and permits required will also be obtained from the South Australian Environment Protection Authority. The construction contractor would identify specific management measures for batching plants in the CEMP (see Section 9.1.6) and relevant subplans.
Table 9.7 Location criteria for ancillary construction facilities Type Criteria Environmental . away from waterways and wetlands . in areas of low conservation significance of flora, fauna and heritage . no substantial clearing of native vegetation required, or located where future clearing is required for permanent works . away from residences or other sensitive receivers . operation of plant would not affect land use of adjacent properties Engineering . easy and safe access to the main road network . adjacent to road and rail corridor . relatively level ground, elevated to assist drainage and allow containment and treatment of runoff . sufficient area . electricity, gas, internet and phone services available or able to be provided without additional environmental impacts . preferably within project corridor or within areas to be acquired by DTEI . easily accessible potable water supply or suitable dam
9.1.6 Contractor’s environmental management plan
A CEMP, prepared for the construction phase of the project, sets a centralised process through which all potential environmental impacts relevant to the project are managed. It outlines a framework of procedures and controls for managing environmental impacts during construction.
The plan will outline how environmental mitigation measures would be incorporated into the construction phase of the project.
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It will be prepared by the successful contractor and document: . roles and responsibilities for planning, approval, implementation, assessment and monitoring of environmental controls . required licences, approvals and permits . potential environmental impacts resulting from the construction of the project, and control and mitigation measures to be implemented . objectives and targets for environmental performance in the form of measurable key performance indicators (KPIs) . annual environmental auditing program of KPIs . environmental monitoring programs . communication procedures . document control procedures . emergency response procedures to mitigate potential environmental damage . training, competence and awareness assessment procedures and programs. Environmental subplans, developed as part of the plan, will include measures to address: . construction traffic management . construction noise and vibration management . soil, erosion and drainage management . vegetation management . weed management . Aboriginal and non-Aboriginal heritage management . dust management . landscape and rehabilitation (for worksites) . community liaison . occupational health and safety . hazards and risk management . spoil management . waste management.
In addition to the CEMP, environmental work procedures and environmental control maps, containing site specific details, will be prepared (and implemented) during construction.
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9.1.7 Landscape works Weed control A weed management plan will be prepared to identify weeds before construction to determine a plan for their control/eradication. Weeds in the road corridor will be controlled before topsoil stripping, topsoil stockpiling and planting works. The management plan will include minimising the risk of construction activities transferring weeds to or from neighbouring properties, ecologies and agricultural or horticultural lands.
Soil treatment and preparation Topsoil removed during site clearing and earthworks preparation will be collected and stockpiled on site. After civil works are completed, topsoil conditioning may be needed. If required, slow release fertilisers and water retention agents may be added to condition the soil to improve growth rates, reduce watering requirements and support plants during establishment.
Mulching and staking Where necessary, planting will be protected using tree guards and marker stakes during the establishment period. Vegetation cleared during site preparation will be mulched and stockpiled on site. Mulch, and possibly weed matting, will be used to suppress weeds and maintain soil moisture. The large area to be landscaped and significant volume of mulch required, may warrant using mulch manufactured from recycled sleepers, timber pallets and green waste.
Planting and seeding A variety of planting and seeding techniques will be used to establish landscaping and revegetation in the corridor and in any wetland offset areas, and may include: . semi-advanced tree planting . tube stock planting . direct seeding . hydro-seeding. All seed and plant material would be sourced locally.
Planting Semi-advanced trees will be used in high profile locations (Section 8.13). Tube stock and virocells will be primarily used for feature planting and revegetation where direct seeding is not possible nor practicable, or the required quantity of native seed not available.
Direct seeding Direct seeding will be used as a preferred method of planting in some revegetation areas. It can be used for a variety of trees, shrubs, groundcovers and grasses, and
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directly sows seeds on site. This method gives a more natural appearance than tube stock planting, as success rates and density vary over areas. Thus the mix and spread of plants in an area becomes more random and more ‘natural’ in appearance.
Direct-seeded plants are generally healthier and stronger, with less root disturbance, than those planted as tube stock. This leads to healthier plants that are more tolerant to drought and pests. Direct seeding can be more cost effective than planting as it is less labour intensive and less maintenance is required after plants are established.
Direct seeding is not necessarily the best option for all revegetation as it relies on: . the desired plants being easy to grow from seed . large volumes of seed being available due to varied germination success rates . appropriate weather conditions to encourage germination and establishment . ongoing weed control to reduce competition for water and soil nutrients.
The direct seeding method of revegetation also makes it hard to control planting density and ensure the desired visual appearance and performance.
Hydro-seeding The verges, median, some embankments, and large open areas of the road corridor will be seeded with a dryland grass mix using hydro-seeding techniques, in accordance with landscape and urban design requirements. It will not be applied as the sole treatment or technique of planting.
9.2 Operation
9.2.1 Road Traffic management No traffic signals are proposed for the interchanges, which will be controlled by the use of roundabouts and alignment design.
Surveillance and incidents The operation of the Northern Connector road will be monitored and managed remotely through DTEI’s Traffic Management Centre, which provides this service across metropolitan Adelaide 24 hours a day.
Managed Motorways The Northern Connector road would be a managed motorway. Managed motorways use Intelligent Transport Systems (ITS) to improve access to, and the safe and efficient management of traffic flow along, urban motorways. The following measures would be employed on the Northern Connector (including the Port Wakefield Road Corridor).
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Primary measures: . Lane use management systems (LUMS) - manages lane use around incidents without total loss of motorway capacity; . Hard shoulder running where emergency break down lanes are used as supplementary lanes during peak periods; . Ramp metering - coordinated use of traffic lights on motorway on-ramps to control the rate at which vehicles merge with the main motorway traffic stream (ramp signals). Vehicles generally proceed individually on a green light; . Variable speed limits (VSL) - supported by variable message signs to prevent the occurrence of further (secondary) incidents after an initial crash, to improve safety during hard shoulder running, and/or during extreme weather events. . Freight and public transport priority typically at ramps in conjunction with ramp metering for general vehicles.
Secondary Measures: . Incident detection using closed circuit television (CCTV) cameras, webcams, weather monitoring stations and emergency telephones; . Automatic number plate recognition (ANPR) to monitor freight movements. . Traffic and traveller information services, such as Variable Message Signs (VMS) with real-time advice about travel times and/or current speed. . Speed enforcement using speed cameras.
Supporting ITS
Other supporting ITS equipments used on the Northern Connector will include high speed tele-communications, smart lighting, vehicle detectors and sustainable energy/power supply. An example of ITS applications on a managed motorway is illustrated in Figure 9.1.
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Figure 9.1 Example of Intelligent Transport Systems Applications on a Managed Motorway
General maintenance methods and programming Northern Connector road Maintenance of the Northern Connector road will be the responsibility of the Metropolitan Region of DTEI.
Road works and road furniture (e.g. road pavement, line marking, reflective pavement markers, kerbing, signs, barriers, stormwater pits and small culverts) will be managed under fixed maintenance contracts. Large culverts and bridges would be inspected regularly by DTEI’s Pavement and Structures Section. The maintenance requirements and schedule is determined by a five-year rolling inspection regime. Road lighting structures and wiring fall under the responsibility of the Electrical Assets Section of DTEI. Any maintenance requirements are generally undertaken by DTEI’s Field Services team. Replacement of road lighting fixtures (complete lighting unit of a lamp or lamps, along with parts designed to distribute the light, hold the lamps and connect them to a power source) is typically the responsibility of the local electricity owner and operator.
Local roads The local road network and its ongoing maintenance would be managed by the relevant local council.
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9.2.2 Rail
The Northern Connector rail will be used for freight trains and interstate passenger trains, and not carry any metropolitan TransAdelaide passenger trains. All existing rolling stock will be permitted to operate on the line. Diesel rail maintenance vehicles will operate only under special operating conditions. The maximum design speed for trains along the Northern Connector will be 115 km/hr. Generally, corridor line speed limits and locations of speed-boards will be designed according to: . track and signalling requirements . standards . rolling stock performance . consideration of driver human factors.
The Northern Connector rail will include one 4 m wide maintenance and emergency track on the western side of the rail to allow for maintenance of the rail (Figure 8.2). Access to these tracks would be via the northern end at the Northern Expressway and at the southern end at Dry Creek marshalling yard. Additional maintenance access easements would be identified as necessary and included during the detailed design phase. The project will be designed and constructed to ensure effective maintenance with minimum whole of life cycle costs. All planned maintenance will be conducted according to approved operations and maintenance policies and practices. If required, occupation periods would be arranged with ARTC where maintenance work is necessary near or over the tracks.
9.2.3 Operational environmental management plan
An operational environmental management plan, prepared to coordinate ongoing monitoring and maintenance after the Northern Connector is opened, will include requirements for maintenance, monitoring, auditing and reporting by DTEI.
9.2.4 Landscape maintenance
Landscaping maintenance will include weed control, grass slashing and tree pruning. Maintenance activities will ensure that plantings establish and achieve the greater landscape design intent of reduced visual impact, enhanced visual, social and environmental quality and safety.
During the 2–3 year planting and establishment period, a watering scheme to help landscape plantings survive, will be necessary and undertaken as part of the project. Following this period, plantings would rely on natural rainfall only.
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Weed control A weed control program will minimise competition between weeds and new plantings. After the establishment period, the weed control focus would be on removal of declared and environmental weeds from the corridor. Open grassed areas would be regularly slashed in accordance with maintenance contract standards to prevent fire hazards in the project corridor.
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For more information
For more information, to make an enquiry or join the mailing list contact the Northern Connector project team. Phone: 1300 793 458 (interpreter service available) Email: [email protected] Visit the website: www.infrastructure.sa.gov.au and then follow the prompts.
1 www.infrastructure.sa.gov.au 1300 793 458 2
Project Impact Report Volume 1 An environmental, social and economic assessment