Civil and hydraulic engineering

Civil and hydraulic engineering (GWW in Dutch) is one of the major consumers of materials in the Netherlands. Every year, more than 20 million tonnes of material is used to extend and improve our roads, canals, engineering structures (bridges, locks, etc.) and subsurface infrastructure (source: SKAO, Roadmap for a climate-neutral infrastructure sector, see background information). In many cases these objects are technically not very complex and designed for long term usage.

Aspects of circular civil and hydraulic engineering

Circular principles for civil and hydraulic engineering often focus on the material level. This includes, for example, reuse of existing material, extending the life of objects or materials, or – for temporary constructions – future disassembly.

Rijkswaterstaat has developed a set of circular design principles for civil and hydraulic engineering, that has three layers:

  • Prevention: prevent use of materials
  • Value retention: retaining the value by extending the life cycle of objects and reuse of components or materials
  • Value creation: designing and constructing of new objects aimed at a long life cycle, durability for the future, optimal management & maintenance, and sustainable use of materials

Design for adaptability

Approximately 90% of engineering structures (e.g. bridges, overpasses and locks) owned by central government are demolished when they are functionally outdated. However, they are not end-of-life. Long term adaptability is therefore an important principle to extend the functional service life of objects. This is particularly true for engineering structures such as bridges and flyovers.

For instance, a set of newly developed standard joints for movable bridges has increased their adaptability. For this example of Industrial, Flexible and Demountable (IFD) building, a Netherlands Technical Agreement (NTA) has been developed. The NTA describes the standard dimensions for the joints between various parts of a bridge, so they can easily be replaced and components can be reused in other bridges in the future. The Provinces of Noord-Holland and Overijssel Work are currently preparing the construction of the first two new bridges designed according to IFD principles.

Design for disassembly

Occasionally, the need may arise to build a temporary structure, such as a cycle path or a flyover. This may include the desire to be able to disassemble the product at some point in the future. For this reason, more and more circular civil and hydraulic engineering concepts are being developed that meet these needs. Think, for instance, of a cycle path constructed of separate panels that can be disassembled. Or the circular flyover (Dutch) that has been developed by Van Hattum & Blankevoort for Rijkswaterstaat. Once its period of use has come to an end it can be dismantled and rebuilt elsewhere.

Environmental impact of applied materials

For many civil and hydraulic engineering projects the technical challenge is relatively simple: to build an object according to an agreed design. Environmental gains can be achieved by managing the environmental impact of the applied materials, for instance by means of a life cycle analysis (LCA), the outcome of which is expressed in the MKI (environmental cost indicator). An LCA measures the environmental impact of the entire production system needed to deliver materials: energy consumed, extra materials, transport and emissions are all taken into account. LCAs often show that the environmental impact of reused materials is relatively low compared to the impact of new materials. The DuboCalc instrument could help to determine this impact.

The Bouw Circulair (Build in a circular way) network has developed standard requirements for, for instance, concrete products. This is especially useful for municipalities that want to include these requirements in their basic specifications. The requirements cover a maximum environmental cost value (MKI) and a minimum percentage of recycled material.

Investment costs, TCO and LCC

In civil and hydraulic engineering projects, price often plays a dominant role in the award process. To achieve circular ambitions, it is important to take the qualitative aspects into take into account as well, such as the life cycle performance of products. This requires a different perspective on costing.  It makes more sense, therefore, to focus on Total Cost of Ownership (TCO) or Life Cycle Costing (LCC). The breakdown into various costs is shown in the figure below, that is described in more detail in this (Dutch) publication.

Different perspectives on costs. Source: PIANOo (2016) Life cycle costs as award criterion
Different perspectives on costs. Source: PIANOo (2016) Life cycle costs as award criterion

 

Tips

  • Choose circular design principles that fit with your project. Explain your choices to the market players in advance, thus enabling them to come up with the right solutions. Not all design principles can be applied to every type of project.
  • Determine in advance whether or not you want to have an adjustable Work, or one that can be disassembled. This is desirable for some projects, but not for others, depending on your needs.
  • Manage on lowering the environmental cost of the applied materials. Asking for an environmental cost indicator (MKI) could be helpful in this respect.
  • Find ways to procure management and maintenance together with the realisation of the project, especially for smaller projects: this gives market players an incentive to increase quality.

Inspiring examples

Background information

Tool - DuboCalc

DuboCalc enables you to make transparent the environmental impact of a project, based on data in the National Environment Database.

Suggestions and/or additions?