Adaptation of road infrastructure to climate change

Project 6
Projected climate change and designing of road constructions
Source: Federal Highway Research Institute (BASt)

Description

Asphalt’s properties are greatly influenced by the thermal conditions of the road, which is in turn shaped by the ambient temperature. The higher the temperature, the lower the rigidity of the material and thus the higher the probability of damage. Higher temperatures can also lead to damage in concrete carriageways. As heat events increase due to climate change, temperature-related variables have to be adapted accordingly during the dimensioning of road pavements.

The strategies of taking weather influences into account at the dimensioning stage of road pavements as applied today, whether in the case of a new construction or maintenance of existing roads, are based on long-term series of meteorological observations. The derived parameters are mean values of past extreme weather events. When planning a road’s future period of use, not taking climate change into account risks miscalculation of the dimensioning and thus also risks shortening the period of use.

Therefore, the research project investigated to which extent an adaptation of weather-dependent input parameters in standardised and mathematical dimensioning of road pave-ments is necessary.


Methodology

The analysis was based on current regulations for the design of asphalt and concrete road pavements, which are: „Directives for the Standardisation of Traffic Area Surfaces“ (RStO), „Directives for the mathematical Dimensioning of Asphalt-paved Traffic Area Surfaces“ (RDO Asphalt) and „Directives for mathematical Dimensioning of Concrete-paved Traffic Area Surfaces “ (RDO Beton).

A total of seven model regions featuring varied projected climate changes were included in the study. Relevant climate data was extracted from the REMO model calculations of the Federal Environmental Agency (UBA). As it was only the impact of climatic parameters on construction to be defined, traffic loads up until the year 2100 were taken as a constant, thus making it possible to ascertain the individual impacts of changed temperatures on road surfaces. Here the mountings (layer sequence and density) as well as thermo-physical material characteristics varied.

In conclusion, the adaptation requirements were evaluated according to the dimensioning procedures.


Results

In the case of asphalt pavements, higher temperatures in road construction lead to an increased damage sum within a 30-year observation period. The development is area-dependent. The tendency is that southern territories experience greater changes in the average 30-years surface temperatures as do the northern territories and a shortening of the period of use is also linked to this.

An effective adaptation measure is modifying the mechanical and thermal properties of the asphalts used. Adapting the thickness of the asphalt layer is one method, however this also carries with it a greater risk of plastic malformations.

In 97% of all concrete pavements studied, only a minimal increase in thickness of less than 10 mm would be required. The studies, however, could not conclusively explain as to whether other influence factors such as changing precipitation amounts or freeze-thaw cycles would have negative impacts on the durability of the concrete pavements.


Project data

Projektdaten

Term of project: 01/02/2012 – 05/09/2014

Contractor:
Chair of Pavement Engineering, TU Dresden

Contact:
BASt unit Z5
This email address is being protected from spambots. You need JavaScript enabled to view it.

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