By Paul Gorman
The digital transformation of the Coffs Harbour Bypass shows how innovation can set new benchmarks for nationally significant infrastructure projects.
Traffic congestion around Coffs Harbour in the Mid-North Coast region of New South Wales has been worsening in recent years, due to a growing population, rising visitor numbers, and the increasing movement of heavy freight.
Global design and engineering company Arcadis was chosen to spearhead a A$2.44 billion Coffs Harbour Bypass to combat the problem, co-ordinating the work of more than 15 partners using Bentley Systems’ above-ground and Seequent’s below-ground products to manage a highly complex project.
Coffs Harbour bypass. Source Bentley Systems
The bypass runs through an area of complex topography, where the sandstone layers of the Great Dividing Range meet the Pacific Ocean. With a scheduled completion date of December 2027, the bypass project is one of the final pieces in the Pacific Highway upgrade programme.
At 14km long, the bypass had to overcome some major challenges, including steep terrain, soft soils, and variable geology and complex rock formations. It also had to tread softly around environmentally sensitive protected rainforests and cultural heritage zones.
Arcadis Senior Road Designer Kane Petrie said the digital delivery strategy used on the bypass had led to measurable efficiency gains, cost savings, and environmental benefits at every stage.
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Different approach needed
The complexity and multidisciplinary nature of the bypass project required Arcadis to take a different approach, one powered by Bentley Systems and Seequent.
Steep terrain meant more than 20 bridges were needed, along with three tunnels with a combined length of more than 1.5km. The project called for 12km of new carriageway.
‘From the outset, we recognised that traditional document-based workflows were not scalable for a project of this magnitude — particularly with the integration of tunnels, bridges, interchanges, and real-time co-ordination between more than 15 design partners,’ Petrie said.
‘We implemented a connected data environment using ProjectWise, ensuring all teams had access to the latest model versions with strict governance, version control, and traceability. This was foundational to managing geographically dispersed teams and rapidly evolving design requirements.’
The Bentley iTwin model enabled real-time design validation, visualisation, and cross-discipline collaboration, allowing Transport for NSW and construction partners to engage and gain faster approvals, reduce rework, and ensure clearer communication across all stakeholders.
‘We combined OpenRoads, OpenBridge, and OpenTunnel to create a robust, integrated model representing roads, structures, and tunnel geometry in one environment. This enabled seamless spatial co-ordination and automated cross-section validation — critical for meeting clearances and geotechnical tolerances across the three major tunnels.’
Seequent’s Leapfrog Works was used to visualise soft soils, groundwater, and complex rock faces, and PLAXIS analysed them, he said.
‘These tools helped us model risks associated with landslip, settlement, and structural integrity – allowing for proactive mitigation during the design phase.’
Bentley SYNCHRO allowed the project team to simulate construction sequences and plan tunnel-portal access, bridge staging, and traffic switches in a four-dimensional environment.
‘For community consultation and client presentations, we used Bentley LumenRT to deliver realistic animations and flythroughs. This helped simplify complex engineering concepts and fostered community buy-in, especially for sensitive areas like tunnel portals and property-access changes,’ Petrie said.
Environmental and social benefits
Using Bentley and Seequent products significantly reduced the environmental footprint of the bypass project.
Seequent’s PLAXIS and Bentley’s OpenRoads Designer optimised cut-and-fill work and helped avoid 22,000 truck movements, saving more than 900,000km of haulage and cutting carbon dioxide emissions by about 580 tonnes.
‘This not only improved air quality,’ Petrie said, ‘but also reduced fuel consumption, noise pollution, and local traffic disruption during construction.
‘Similarly, PLAXIS and Leapfrog provided advanced ground modelling that enabled early intervention in high-risk geotechnical zones, saving costly field adjustments during tunnel construction.
‘Socially, the project enhances road safety and reduces congestion for over 12,000 vehicles daily. Safer crossings, improved active transport access, and multimodal design principles contribute to a healthier, more connected community.’
Eliminating silos, accelerating decision making
The planning, design, and construction of the Coffs Harbour Bypass set a ‘national benchmark for digital engineering’, Petrie said.
The digital twin, developed through Bentley iTwin, ‘fundamentally reshaped’ the delivery of the project and became the single source of truth across disciplines and stakeholders, saving more than 366,000 work hours.
‘It supported ongoing alignment between road, structural, tunnel, geotechnical, drainage, and services design—enabling smoother handover to construction partners and setting a precedent for future maintenance and asset-management workflows.
‘Bentley’s digital tools were essential in embedding sustainability into every phase of the project, maximising benefits while minimising footprint.
‘By embedding Bentley’s digital building blocks throughout the lifecycle — from design authoring to review, co-ordination, and stakeholder engagement — we created a smarter, leaner, and more resilient project-delivery model that continues to add value into construction and beyond.’
- Bypass removes more than 12,000 vehicles daily from local roads;
- Bypass avoids up to 12 sets of traffic lights, saves 12 minutes in travel time;
- Integrated approach saved 366,000 work hours and A$5 million;
- Accurate modelling reduced carbon emissions by an estimated 580 tonnes.