ORIS worked with Die Autobahn GmbH Des Bundes on a portfolio of three highways projects in Germany (2 maintenance projects and 1 new build) to assess their resilience to climate change. 

Based on the latest data from the Coupled Model Intercomparison Project (CMIP) and other recognized international bodies*, following the findings from the International Panel on Climate Change (IPCC), an assessment of climate sensitivity was performed using ORIS’s digital capabilities, around three main climate risks :

• Maximum temperature;
• Frost change frequency;
• Maximum river discharge.

Maximum temperature: downscaling for the most granular analysis

The monthly maximum temperature data was downscaled in order to be displayed in the highest possible resolution. This downscaling process was carried out by performing a geographically weighted regression analysis, where the altitude is taken into account in order to refine the temperature data. This approach allows a more granular analysis of the impact.

Figure 1: Temperature for A6 project for both current and future scenario

Figure 2: Temperature evolution of A15 project from 2020 to 2050

Frost change exposure: anticipating one of the major causes of highway deterioration

Damages due to freeze-thaw cycles can be one of the major causes of highway deterioration. If the average temperature rise expected with climate change is a major factor in reducing the number of frost change frequency, the overall number of freeze-thaw cycles remains dependent on the location and environment of the project. In this portfolio assessment, the number of freeze-thawing cycles will be diminished by 28 in the region of one project versus by 58 for another one. 

Figure 3: A94 project, Frost Change Frequency (FCF), in number of cycles, for current and future scenarios

Such granular analysis is made possible by using advanced digital solutions. Anticipating the effects of frost/thaw cycles on pavements is important to plan future maintenance needs. For instance, on a cement rigid pavement, the weakening of the unbound granular materials and subgrades in road pavements during thaw periods in frost-affected regions, leads to an early fatigue of the cement concrete surface layer. 

River discharge exposure

River discharge is the volume of water flowing through a river, with - in extreme cases - a high river discharge resulting in flooding and low river discharge resulting in drought. The scenario of evolution allows for a better understanding of areas at risk and anticipate countermeasures.

Figure 4:  River Discharge for the A6 project, in cubic meters per second, expressed by the difference between 2050 and 2018

In conclusion, using advanced digitalization based on internationally recognized data, allowed for anticipating the resilience of a portfolio of highways in Germany to the increased risks linked to climate change, while being very granular in the analysis.

By providing very detailed insights into the highways' exposure to climate change effects, this type of assessment gives the knowledge needed to develop proactive strategies to secure the future of vital transportation networks. Such comprehensive assessments are essential for building resilient roads that can withstand the tests of time.

* Maximum temperature: Centre for Environmental Data Analysis (CEDA) and WorldClim; Frost change frequency: Climatologies at high resolution for the earth’s land surface areas (CHELSA); River discharge: Copernicus, European Union’s Earth observation programme (cds climate copernicus).