As a Temporary Works Coordinator, you need to review and approve working platform designs before piling can commence. This guide explains what to look for in a BRE470 design certificate.
The TWC's Role in Platform Design Approval
Under BS 5975:2019 "Code of Practice for Temporary Works Procedures and the Permissible Stress Design of Falsework", the Temporary Works Coordinator (TWC) has a critical role in the management of all temporary works, including working platforms for tracked plant.
The TWC's responsibilities for working platforms include:
Design brief: Ensuring the designer has been provided with adequate information about the site conditions, the plant to be used, and any special requirements or constraints.
Design review: Reviewing the design calculation and certificate to confirm it is appropriate for the specific site conditions and plant loading. This does not mean the TWC must check every calculation step — that is the role of the independent checker — but the TWC must satisfy themselves that the design is reasonable and complete.
Design check: Confirming that the design has been independently checked by a competent checker, and that the check certificate is included with the design.
Approval and permit: Issuing a temporary works permit to allow construction of the platform, and subsequently a permit to load to allow the plant to operate on the completed platform.
Monitoring: Ensuring the platform is inspected during use and maintained in accordance with the design requirements.
What to Check in a BRE470 Design Certificate
When reviewing a BRE470 design certificate, the TWC should verify the following:
Input parameters match site conditions: The subgrade type and strength parameters used in the design must be consistent with the ground investigation data for the specific location where the platform will be constructed. If the GI data shows cu = 30 kPa but the design assumes cu = 60 kPa, the design is unconservative and must be revised.
Correct rig and loading: The plant loading must correspond to the actual rig that will operate on the platform. Check the rig model, track dimensions, and track pressures against the manufacturer's data or EN 996 specifications.
Appropriate partial factors: BRE470 specifies partial factors for loads (γF = 1.26) and materials (γM applied to tan φ'). Verify these have been correctly applied.
Platform material specification: The assumed angle of shearing resistance (φ'p) must be achievable with the specified fill material. If the design assumes φ'p = 45° (well-graded crushed rock), the material specification must require this grade of material.
Adequate thickness: The calculated thickness should be reasonable for the given parameters. Very thin platforms (less than 300 mm) on soft ground should be questioned. Very thick platforms (over 1000 mm) may indicate that the subgrade is too weak and alternative solutions should be considered.
Designer and checker credentials: Confirm that the designer and checker are competent and that the check has been carried out independently.
Common Issues and Red Flags
In practice, TWCs frequently encounter the following issues with working platform designs:
Optimistic subgrade parameters: Designers sometimes use subgrade strengths that are higher than the ground investigation data supports. This leads to thinner platforms that may be inadequate. Always cross-reference the design parameters with the GI report.
Wrong rig: The design may have been prepared for a different rig than the one actually being used on site. If the rig changes after the design is issued, the design must be re-checked for the new rig's track pressures.
No ground investigation: Some designs are based on assumed subgrade parameters without any ground investigation data. While this is sometimes unavoidable at tender stage, the design should be updated when GI data becomes available. Assumed parameters should be clearly stated and conservative.
Missing check certificate: A design without an independent check certificate is incomplete and should not be approved. The check is a fundamental requirement of BS 5975.
Platform not built to design: Even a perfect design is worthless if the platform is not constructed in accordance with it. The TWC should verify that the correct material has been used, the correct thickness has been achieved, and the platform has been properly compacted.
How Our Certificates Support the TWC
Our BRE470 design certificates are specifically designed to make the TWC's review process as straightforward as possible:
Clear parameter tabulation: All input parameters are presented in a clear table format, making it easy to cross-reference with ground investigation data and rig specifications.
Full calculation audit trail: Every step of the BRE470 Appendix A calculation is shown, so the TWC can follow the design logic without needing to reproduce the calculation.
Cross-section diagram: A scaled diagram showing the platform layers, dimensions, and subgrade helps visualise the design intent.
Professional certification: Each certificate includes a unique reference number and is signed by David Miller, Temporary Works Designer. The design has been prepared and checked in accordance with BS 5975 requirements.
Consistent format: Every certificate follows the same format, so TWCs who review multiple designs from our tool can quickly find the information they need.
For just £299.99 per design, our tool provides everything the TWC needs to review and approve the working platform design efficiently and confidently.
