As part of a study of alternatives for connecting Schleißheimer Straße to the A99/A92, 21 possible alignments with different tunnel options were examined. CDM Smith, acting as a subcontractor to INGE Grassl-SSF-Amberg, was commissioned to analyse the impact of these alternatives on the climate. The aim was to create a sound basis for decision-making in order to incorporate climate-related aspects into the assessment of the alternatives at an early stage.

The early planning stages offer the greatest flexibility for decision-making. This is the ideal time to assess and compare the climate impacts of different alternatives and ensure they are considered alongside other project criteria. By identifying climate-related effects early, project teams can better understand the long-term implications of their choices. This supports more sustainable infrastructure planning and can help avoid costly modifications later in the project lifecycle.

We assess multiple sources of greenhouse gas emissions throughout the entire project lifecycle. These typically include emissions associated with the production of construction materials, construction activities and changes in traffic patterns. Depending on the project, impacts on land use and potential carbon sinks may also be taken into account.

This cross-sectoral approach is guided by the provisions of the Climate Protection Act and enables a structured classification of the results. By considering construction, transport, industry and land use together, interdependencies can be identified and informed decisions can be made to support climate protection goals.

One of the most effective ways to reduce greenhouse gas emissions is often to minimise the amount of construction material required. As a result, alternatives involving shorter routes or tunnel sections generally perform more favourably. In addition, lower-emission materials, such as CO₂-optimised concrete, can be used. Furthermore, CDM Smith recommends to design structures to be as modular as possible to facilitate subsequent deconstruction, the reuse of materials or alternative uses. As this is an early stage of planning, the identified optimisations can easily be incorporated into subsequent stages and can be implemented cost-effectively. 

The results of the carbon assessment were incorporated into the selection of the preferred option as part of a comprehensive evaluation matrix. This ensured that climate-related impacts were considered alongside other environmental and planning criteria. In addition, we translated the assessment results into environmental costs.

Presenting climate impacts in the form of environmental costs makes the results easier to understand and compare. It allows the consequences of different project alternatives to be evaluated from both an environmental and an economic perspective. This additional level of transparency can support more informed planning and decision-making.

As the project progressed, the City of Munich placed particular emphasis on construction-related emissions in order to be able to reduce them in a targeted manner during the next planning phases. On this basis, future planning decisions can be aligned even more closely with climate-related criteria.