In the global move towards net zero, the impact of civil/structural engineers to reduce emissions and meet decarbonisation targets should not be underestimated. The government has committed to a 51% reduction in emissions by 2030 and a net zero target by 2050(1).
Engineers and stakeholders within the infrastructure sector have a significant role to play in addressing the climate crisis and achieving this target. Taking a bridge underpass as an example, Figure 1 outlines the scale of the impact engineers can have by introducing changes across the design, construction, use and reuse of infrastructure to reduce embodied carbon.
Figure 1: Potential impact of engineers on carbon reduction
Implementation of the circular economy has the potential to play a significant role in limiting global climate change while providing regenerative design for generations to come. To achieve climate neutrality, synergies between the circular economy and carbon reduction need to be established in the context of highway infrastructure.
As highway construction and maintenance accounts for an extensive use of resources, road authorities must become more material and energy efficient, moving beyond recycling, to reuse, repair and minimising use of materials.
Research has shown that one of the most significant routes to embedding circularity is through the demonstration of innovative approaches which can also enhance KPIs relating to life cycle cost and sustainability(5). However, the barrier to this seems to lie in the perception of risk and lack of standardisation related to new construction and maintenance approaches.
CERCOM risk-based analysis framework
The CERCOM (circular economy in road construction and maintenance) project delivers an innovative risk-based analysis framework (RBAF) to facilitate the adoption of circular economy (CE) and resource efficiency (RE) principles in procurement by national road authorities (NRAs) across Europe.
The project was commissioned as part of the Conference of European Directors of Roads’ (CEDR’s) Transnational Research Call of 2020, starting in September 2021.
This two-year project, funded by seven national roads administrations, and undertaken by partners from Ireland, the UK, the Netherlands and Denmark, aims to understand the technical, operational and procurement opportunities and barriers to moving towards more circular practices.
The project developed a risk-based framework and management tool to facilitate a step change in the adoption of RE & CE principles in procurement and multi-lifecycle management by NRAs across Europe.
The aim of the RBAF is to facilitate procurement of circular solutions for road construction and maintenance while assessing the risk of doing so, allowing uncertainties associated with novel methods or materials to be quantified.
The framework is applicable to all road infrastructure elements under the maintenance remit (eg, road pavements, bridges, retaining walls, cuttings and embankments and roadside infrastructure).
For this project, it was essential to integrate circularity factors into procurement practices. However, when considering procurement, it is necessary to also consider more traditional criteria such as performance, cost, environmental and social factors. As such, the RBAF was developed to take account of all these factors. There are five steps within the risk assessment framework:
- Establish context – includes the primary goals of the assessment, the hazards involved, the potential actions to reduce risk, the consequences to be considered and how the hazards and consequences will be calculated, identifying the specific spatial and temporal boundaries of the assessment in question;
- Evaluate likelihoods – includes details on likelihood of a 'failure' event (Pf) or the probability of exceedance of a given damage state for given scenarios of hazard and action;
- Evaluate consequences – includes direct and/or indirect consequences/costs associated a with failure event;
- Establish additional KPIs – involves quantification of RE&CE, cost, environment and social KPIs;
- Optimise – involves optimisation of various assessment criteria and KPIs.
For each potential construction or maintenance option, the risk associated with this strategy is calculated (Risk = Pf x Consequences of failure event). Within the RBAF, consequences are taken as the costs associated with a failure event (eg, the direct and/or indirect costs associated with emergency resurfacing due to premature loss of skid resistance). Any number/type of consequence may be considered in this regard and the process should ideally consider the full range of potential outcomes.
The developed additional KPIs ensure that contractors can be rewarded for producing a scheme that will be long lasting, cost effective to maintain, use limited amounts of raw materials, designed for multiple lifecycles and/or can be readily repaired for (multi) life extension.
A system of ranked interpolation is used to quantify KPIs. The first rank for each KPI is assigned a value of 0.0, and the final rank is assigned a value of 1.0. In the simplest case, a linear relationship is assumed between the first and final rank.
Where a more subtle response is required, a multi-linear or quadratic relationship may be determined between different KPI ranks. Ideally, KPIs should relate to existing targets and practices already defined by the overseeing NRA.
For example, an NRA with a target to use more recycled content in maintenance schemes may already define different 'levels' or ranks of achievement of this goal. These 'levels' can be related to KPI values and ranks for quantifying KPIs for potential schemes. An example is outlined in Table 1.
Within the optimisation process, to rank various construction or maintenance solutions, a single metric called the Net Risk Reduction Gain (NRRG) is used to score the various potential maintenance strategies, amalgamating performance, cost, RE&CE, environmental and social factors using a weighted sum. As with any tender evaluation, weight factors are used to quantify priorities of each NRA for a specific project/scheme.
Within CERCOM, a software tool was developed encompassing the RBAF to provide a user-friendly Excel based tool to facilitate the procurement of RE&CE construction and maintenance options, while also considering costs, as well as the performance risk associated with more innovative methods/materials.
The functionality to incorporate additional environmental and social factors is also included, allowing NRAs to evaluate options considering a broad range of evaluation criteria.
The developed tool provides sufficient flexibility to allow NRAs to decide on the level of engagement with the CE process, based on current CE maturity as well as future needs.
Within the developed framework and software tool, the functionality and capabilities can be adapted to suit the maturity of NRAs at any given time and can also be tailored to suit the scope and type of scheme under consideration. As such, it will prove to be a valuable tool in the move towards a circular approach in the procurement process of construction and maintenance of road infrastructure.
Integration into procurement practices
For CERCOM, the objective is to incorporate the RBAF into existing public procurement processes, introducing the quantification of RE & CE KPIs in the consideration of construction and maintenance strategies and life cycle analysis.
Typical procurement processes outlined in the Office of Government Procurement Public Procurement Guidelines for Goods and Services(6) and European Commission’s Public Procurement Guidance for Practitioners(7) were reviewed.
On this basis, it is envisaged that the RBAF tool be used primarily by NRAs as part of the preparation phase and the pre-tendering phase as an iterative process, while also informing the development of tender documents as part of the tendering procedure phase, as illustrated in Figure 2.
Figure 2: Integration of CERCOM RBAF into Existing Procurement Practices
Integration of existing tools and policies
The Netherlands was the first European country to formalise the process for sustainable procurement, with the Dutch government establishing clear goals as early as 2005 and embedding this further into their procurement processes.
Rijkswaterstaat (the department of public works of the ministry of infrastructure and the environment) developed a methodology for infrastructure projects where the functional specification of the tender together with the quality input from the client ensure an innovative and high-quality solution.
The criteria that formed the basis of assessing the sustainability attributes of tenders were CO2 emissions and environmental impact (Lamb et al., 2022b). To facilitate this, the following two tools were developed to measure CO2 emissions and environmental impacts, and are now mandated to be used by all tenderers:
- The CO2 performance ladder – a certification system with which a tenderer can show the measures to be taken to limit CO2 emissions within the company and in projects, as well as elsewhere in the supply chain.
- DuboCalc – a life-cycle analysis (LCA) based tool which calculates the sustainability value of a specific design based on the materials to be used. Bidders use DuboCalc to compare different design options for their submissions. The DuboCalc score of the preferred design is submitted with the tender price.
In 2022, Transport Infrastructure Ireland (TII) published a guidance document on the use of the TII carbon tool, which was developed to assess the main sources of carbon emissions throughout the lifecycle of a project, from design, construction, maintenance, operation and end of life(8).
The goal is to align with best practice and enable industry to identify and quantify where potential carbon savings can be made. The tool can be utilised by industry partners to quantify both embodied and operational carbon related to transport and infrastructure schemes in Ireland(9).
One advantage of the CERCOM RBAF is the ability to integrate the results of these tools into the developed framework and build on advances already made in the move towards more circular sustainable options.
The CERCOM software tool provides a means to assess various innovative methods and materials with the goal of reducing material consumption and associated CO2 emissions in highway construction, while also quantifying the potential risk associated with performance and functionality of more pioneering approaches.
It provides a user-friendly, versatile means for NRAs to assess the risk of using innovative circular methods and materials along with additional criteria to facilitate optimum selection of scheme options and associated procurement practices.
In addition, use of this approach provides a means to evaluate the impacts of certain measures and prioritise areas that require further research or investigation.
It is envisaged that the tools and methods described will be updated and refined based on the practical experience gained from analysing various case studies before project completion in August 2023.
This has the advantage of providing a tried and tested multifaceted framework that will be extensively reviewed and verified by the end of the CERCOM project. It will then be available to CEDR NRAs to customise for use in procurement in the move towards a circular economy.
Authors: Dr Emma Sheils, senior engineer, Research Driven Solutions Ltd. (RDS), has worked across several areas of academia and industry with experience in the areas of bridge design, performance optimisation and maintenance of civil infrastructure. Lorcan Connolly, director, RDS, has 10 years of experience in the areas of bridge modelling, design and assessment. He also specialises in probabilistic assessment of structures, global risk assessment and resilience assessment of critical infrastructure.
1) gov.ie - Ireland’s ambitious Climate Act signed into law (www.gov.ie)
2) Gibbons, OP, & Orr, JJ (2022). How to calculate embodied carbon. Institution of Structural Engineers.
3) Sanchez, M (2022). The pursuit of total design of bridges in the era of climate change, Bridge Keynote CERI Conference, Dublin, August 2022.
4) Collings D (2021). The carbon footprint of bridges. Structural Engineering International, DOI: 10.1080/10168664.2021.1917326.
5) Lamb, M, Viner, H, Ramdas, Bailey, H, Connolly, L, O'Connor, A, and Sheils, E, (2022), Good practice inventory of current systems and procurement methods. CERCOM D2.1. Available at: https://cercom.project. cedr.eu/resources/
6) OGP, (2019), Public Procurement Guidelines for Goods and Services, Office of Government Procurement, Ireland.
7) EC, (2018), 2018. Public Procurement Guidance for Practitioners, European Commission.
8) Transport Infrastructure Ireland Carbon Tool for Road and Light Rail Projects: User Guidance Document, GE-ENV-01106, December 2022. Available at GE-ENV-01106 (tiipublications.ie)
9) TII Climate Action Roadmap, December 2022. Available at: TII Climate Action Roadmap