Modular Rockfall Protection Wall

Modular Rockfall Protection Wall

The magnitude 7.8 Kaikoura earthquake caused over 50 landslides along State Highway 1 north and south of Kaikoura.  Damaging both road and railway infrastructure, it brought a key South Island transportation route to a standstill.  Since the quake, multiple teams have been feverishly working on State Highway 1 (SH1) and the Main North Line railway trying to restore these services.  However, the risk of further rockfall poses a significant concern for both human safety and future damage of the new infrastructure.  To address this concern a team was assembled to research, design, build and test an innovative solution, fit for purpose.  

Modular Rockfall Protection Wall

The design and build of the Modular Rockfall Protection Wall (MRPW) solution was a team effort driven by the North Canterbury Transport Infrastructure Recovery Alliance (NCTIR); including Fulton HoganStahlton Engineered Concrete and Geofabrics NZ Ltd. The main challenges facing the design team were space and time - they needed a rockfall protection solution to fit within the narrow coastal corridor and they needed it quickly.   The team worked together to develop a practical solution using materials readily available on site – a key element being the concrete blocks, which are a modified version of the more than 7,000 concrete blocks that have been used to build a new sea wall along parts of the corridor.  Adding in some research on rockfall protection walls, the team developed a new configuration that they thought would meet the needs of the project.  The next challenge was to demonstrate to themselves and to key stakeholders that the solution actually worked.  The dynamic nature of rockfall means that it is not that easy to predict the performance of the wall with a set of mathematical equations or computer models.  For this reason, the team recognised the need to test the wall under real impact loading conditions.  Fortunately for the NCTIR Alliance, the best team to help test the proposed MRPW design was on their doorstep.    

Holmes Solutions undertake design, development and testing of a range of complex, life‑safety products.  This includes full scale, dynamic impact testing of roadside hardware and security products; such as road safety barriers and anti-terrorism bollards. Our expertise and experience in high energy, dynamic testing was integral to completing this project.  With limited test literature available, a full review of national and international standards was required to identify an appropriate benchmark for product validation.  Once identified, Holmes Solutions developed a test programme capable of assessing the impact of a full scale install with 750 kilojoules (kJ) of energy (ie. approx. 25% more energy than a 36,000 kg truck and trailer travelling at 80 km/hr impacting a safety barrier). With the test sample installed at our impact test facility, the next step was to commence the test programme.  Click on the video to see the outcome.

The results speak for themselves.  After multiple impact tests, the Modular Rockfall Protection Wall met the test programme required, enabling confidence in its future use.  A special thanks to Eliot Sinclair who captured the tests using their Leica P40 with 3D Reshaper software and drone.  To learn more about the wider transport recovery effort click here.  

If you would like more information on this test programme, please contact Ben Poulter on +64 3 363 2180 or email info@holmessolutions.com.  Follow us on LinkedIn to receive notification of special events, see more interesting videos and read our latest thought-provoking articles.