Case study: Metro Expansion Design Carbon Savings
Company - Midland Metro Alliance
Going forward the programme will continue to model the embodied carbon impacts of their design and material choices and will look to align reporting and assessments to PAS 2080 standard.
What’s the issue being addressed?
Sustainability is one of MMA’s core values. Their ethos is to adopt responsible and sustainable practices and to deliver the extension works while maintaining a balance between economic success, protection of the environment and social responsibility. A major part of this has involved assessing the embodied carbon impacts of the project.
How was this solved?
MMA utilised the RSSB Rail Carbon Tool (RCT) to support decision making in relation to specific design elements and material selection. Use of the RCT is also supporting the production of a wider Material Sustainability Assessment and scheme CEEQUAL assessments.
For Midland Metro Alliance, the RCT has facilitated a process where low carbon and sustainable solutions can be quickly identified and implemented on future parts of the project, where appropriate, to enhance sustainability.
What were the outcomes?
Using the RCT has had several key successes to date:
- A significant change was made in the track slab design for the Centenary Square Extension, moving from traditional steel rebar reinforced concrete to plastic fibre reinforced concrete. This saved approximately 15% of embodied carbon (kg CO2e) per m3 concrete as well as reducing installation time and deliveries to site;
- Ductile iron drainage boxes were originally specified on the project. As an alternative, polymer concrete boxes have now been specified. This change will reduce embodied carbon of the drainage boxes by approximately 50%. The polymer concrete drainage boxes are also lighter;
- A simple design change saw the material specified in expansion joints change from stainless steel to plain steel dowel. This design change reduced embodied carbon of the expansion joint reinforcement by approximately 50%.
These embodied carbon savings, when multiplied up over the whole area of the project, will be significant whilst also having positive financial and health & safety impacts through easier and quicker installation and reduced time on site.
Carbon Smart, Reducing our Environmental Impact.