Sydney has long been celebrated for its numerous walkways through bushlands and alongside its numerous natural waterways. One such waterway is the Narrabeen Lagoon, located alongside Sydney’s Northern Beaches. Local residents love spending weekends walking, cycling and running along its shores, and people travel from all over Sydney to enjoy the area. Now, with the scenic Narrabeen Lagoon trail providing a stunning 4.8km circuit track around Narrabeen Lake, along with its bridges, crossings and shelters, people can take in every aspect of the Lagoon, without ever leaving the track.
There are always unique challenges when building a walkway through dense vegetation within highly sensitive and protected ecosystems. With this project, much care had to be taken of the abundance of wildlife, historic sites and cultural heritage. There were also broad expanses of water that needed to be crossed with single span bridges – 52 metres across Middle Creek and 32 metres across South Creek. Then there were the challenges of creating structures that were sturdy and durable while maintaining the original design intent.
All these challenges had already been presented to other construction teams, but they all proved to be too much for them to handle.
Thompson Berrill Landscape Design (TBLD) had been engaged by Warringah Council to develop the walkway. An initial engineering concept had already been completed by another firm, but it was incomplete and didn’t live up to the basic engineering requirements. So TBLD turned to our team because we had the people in our Design Engineering Hub who could provide the specialist knowledge, skills and expertise they needed.
We immediately took the project back to the Discovery phase so we could pin-point the key objectives of our partners and identify exactly where the previous designs had fallen short of the requirements.
We ran a series of collaborative workshops with our partners and, through these sessions, we were able to reimagine the design vision and deliver an alternative that would confidently live up to TBLD’s vision.
Community involvement had already been encouraged through the Council’s planning phases. For example, kayaking is really popular on the lagoon and local kayakers had been consulted when the design of the bridge was being formed. We wanted to acknowledge their input in the design of the bridges somehow, so we created a design for the side of the lagoon bridge that was inspired by their orange oars. All through the development of the structural designs, we kept the design intent intact while introducing interesting new themes like this. We then presented this to Council and TBLD who were happy for us to continue to the next ‘Detail’ phase.
All through the detail development stages we were working with Warringah Council and TBLD. Together we formed a pretty formidable team. The technical, operations and construction teams considered the project, brainstormed the challenges and developed strategies for dealing with likely issues during the design phase. This multi-skilled team wanted to deliver the most aesthetically dynamic and environmentally sound design possible, and they open-heartedly collaborated to ensure it was achieved as cost-effectively as possible.
The delivery of a project like this requires masterful logistics planning. The time we invested at the ‘Discovery’ and ‘Develop’ started to pay huge dividends by the Delivery phases because we were now installing the Middle Creek and South Creek bridges in the dense bushlands with access only through highly sensitive and protected ecosystems.
With input from the riggers, the group concluded that using pontoons to move the bridges into place risked damaging the riparian zone through potential oil spills. Furthermore, the groundwork required for the cranes to be capable of lifting the pontoons into the water would have created too much damage. Early on in the Discovery phases, the investigation showed that the groundwork required to set up cranes to lift the bridges into place was pretty much the same as for the pontoons. So the teams dropped the pontoon option and used cranes to carefully lift the bridges directly into place. This was elegant, although much more difficult solution to execute successfully because one of the bridges was a staggering 52m long!
In the website, ‘Best Sydney Walks’ they say: “The completion of the Narrabeen Lagoon trail in 2015 has made Narrabeen Lakes the perfect spot to escape the city and the suburbs. With an abundance of activities you can choose from, the Narrabeen Lakes area is a great day out for the whole family. A beautiful wooden boardwalk and steel bridges make it now possible to do a full, uninterrupted loop around Narrabeen Lakes.”
This project has definitely resulted in an immensely popular track. All of the design intents were achieved and Council continues to be very happy with the result. By working so closely, collaboratively and intuitively with our partners, we were able to develop a track that is loved by everyone in the community.
The track is experienced in four stages which are connected by bridges and major infrastructure at creek crossings. Walkers can enjoy the many rest and break-out areas, where there are BBQ recreation areas and shelters. Where the track is laid on the ground, we used crushed sandstone paths or concrete paths. The 4th part of the track comprises the areas surrounding the lagoon that are marshy, continually wet, and prone to flooding. In these areas, we designed and constructed a low-lying boardwalk system as can be seen here.
Designed specially to allow for pedestrians and cyclists on the shared path. This picture shows the perfect co-existence of both groups. The dogs also love it!
The kayakers are a major feature of the whole Lagoon, and they were consulted when the design of the bridge was being formed. Because they’re always on the lagoon, we wanted to pay them a little tribute through the design. You can see the orange oars featured on the side of the bridge. These oars have no structural value, they’re purely artistic.
We had strong design intentions within a framework we wanted to achieve – i.e. the form, colour, shape, and the way that it was constructed. Fleetwood took that concept and successfully translated it into the built form. They’ve done an excellent job.Glen Berrill Director, Thompson Berrill Landscape Design