The project includes upgrading around 14 kilometres of the Pacific Highway at Coffs Harbour, starting from south of England’s Road roundabout and finishing at the southern end of the Sapphire to Woolgoolga project.
The project will deliver four lanes of divided highway to a motorway standard and will bypass the Coffs Harbour Central Business District. When completed the bypass will form part of the Pacific Highway and the national land transport network.
Objective/benefits of the project include:
- Travel time savings for passing and local traffic
- Improve the amenity of the Coffs Harbour CBD by removing significant passing traffic.
- Ease congestion by removing thousands of vehicles from the Coffs Harbour CBD
- Improve safety for all road users along the existing Pacific Highway
- Improved freight efficiency
- Improved accessibility to the Coffs Harbour CBD
- A more reliable route, with flood proofing to that of a 1:100 year flood event
- Result in wider economic benefits for the Coffs Harbour area by making the CBD a more attractive place to visit, shop and work
The key overall objectives for Quickway’s involvement on the project included:
- Provide management and construction crew resources to complete all the utility relocations
- Design and constructability reviews to achieve program and cost benefits for TfNSW
- Expedite the Program which was significantly behind schedule (by 12 months)
- Complete the works in various areas ahead of the main civil works for Coffs Harbour Bypass, in order to avoid significant commercial and reputational damage to TfNSW.
The scope of works included the following Utilities, mainly in the northern section of the project:
- Design and constructability reviews for all of works, including development of design from 80% to IFC for all Watermain and Electrical works.
- Water main installation of 11 kilometres of pipe, pits, valves, & other fittings
- 1km of 500mm diameter DICL (including 2.3km of dual main, Reuse and Potable Water)
- 8km of 450mm diameter DICL
- 6km of 100-300mm diameter DICL
- 0km of OD630 HDPE Temporary Bypass Mains
- Electrical construction for Essential Energy assets, including:
- 2km of 66kV Underground Sub-Transmission Feeders
- 2km of 11kV Underground Distribution Feeders
- Installation of 23.5 km’s of high voltage (66 & 11kV) Electrical cabling, with a significant portion (circa 30%) of overhead electrical cabling.
- Telecommunication installation works for Telstra, City Smart, NBN, Vocus and Optus
- 9km of trenching and trenchless excavation
- 38km of Telco Fibres and associated conduits.
- Construction of many (43 no.) trenchless (HDD and Micro-Tunnel) bores across the project, including:
- Two complex HDD’s (both between 350 and 450m long) on a busy street, and in close proximity to multiple existing utilities, residents, pedestrian/traffic, and Korora Public School. (Note: works undertaken following extensive potholing/12D modelling of all services, on a closed street, and during School holidays period).
- Several Case Bores across the project, including dual bore crossings under Pacific Highway.
Additional scope items included:
- Pre-condition and Post Condition surveys
- Procurement of all pipes, fittings, conduits, concrete, reinforcement, and quarry materials
- Contamination management, clearing, and Panama disease management
- Environmental Management of entire works
- Quality Management compliance
- Traffic Planning and Management for the works
- Earthworks, laydown sites, and access track construction
- Utility protection
Although the Designers were contractually engaged by TfNSW, Quickway worked with each design partner to further develop and improve the design, as well as improve the construability, operation, and future maintenance of the assets. On award of the contract to Quickway, the designs were developed to the following stage:
- Water Design
Coffs Harbour City Council (CHCC) had multiple design packages which were at different levels of completion, ranging between concept design and 80%. Due to TfNSW’s overall program being 12 months behind schedule prior to Quickway’s involvement, there was time-constraint pressure on CHCC to develop the first two packages to IFC within 2 months. This design however included a lot of assumptions, notes such as “TBC”, while the network constraints were not factored into the design. These constraints included single potable trunk main isolations at a time, due to bulk water supply flowing between reservoirs. This presented several challenges including:
- As the DN500 DICL pipes carried an extended lead time, and the 80% design was arguably not at the level you would expect of an 80% design, this introduced significant risk to the procurement and program.
- CHCC did not have thorough modelling of their network to feed into the design, which meant that additional investigations were required to develop the designs.
- The network constraints imposed a large impact on the overall project staging (including other new assets), and additional works for complex temporary bypass arrangements.
- Electrical Design
Essential Energy had draft uncertified drawings (50% designs) on contract award. The designer for the works, Gosling Electrical, was significantly behind program due to resource capacity constraints and because they were completing the design for the central and southern sections of the project also. Even though the design was more advanced than the Water design, TfNSW requested Quickway to support by reviewing and identify any technical issues with the design as well as areas with opportunities.
- Telecommunication Design
Telstra, NBN, Optus, Vocus, and City Smart Solutions all had significant assets to be installed for the project, with each provider producing their own concept design. On contract award each of the packages were already many months behind schedule. The main challenges with the design for the Telecommunication included:
- Trenchless designs did not have achievable bending radius for bore sections.
- Depth of cover was too shallow for the swampy areas, which could cause a risk of frac-out.
- As each asset owner provided their own design independently, there was some clashes with proposed and existing assets. The designs were not integrated together.
- The project was approved under a “low impact works” approvals conditions, therefore tree and vegetation clearing was to be kept to a minimum. This resulted in a narrow construction corridor with the telecommunication assets as close as 1 metre to the project boundary, requiring amendment of the design.
- Staging of the works was not considered in many areas, which result in change to design and additional construction works for temporary telecommunication conduits and fibres. To achieve cut-overs within the required timeframe noting the fibre assets included the main Sydney to Brisbane link.
- Overall Design
One of the main challenges with all the designs was the fact that a lot of the alignment (for Water, Electrical, and Telecommunications) was designed as underbores – however this did not consider the ground conditions, which varied between hard rock (up to 250MPa) in some areas, and swampy ground conditions in other areas. With trenchless excavation (bores) in this strength rock, and/or varying ground conditions, this would result in significant additional costs and time impacts to TfNSW and the project.