Frost zone

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Germany is currently divided into three frost zones for the purpose of frost-proof design of the road superstructure ( frost protection construction ) . This classification is based on experience and knowledge from the frost effects of winter 1962/63. It was a very long and severe winter. The map was created by the “Frost” working group and the “Earthworks and Foundation Engineering” working group. The decisive factor is the consideration of frost-endangered and frost-sensitive soils of soil classes F2 and F3. There is no risk of frost damage to F1.

Climatological knowledge

Day temperature T: max / med / min
Day temperature  T : max / med / min

Air temperature dependent days
  • T max  ≥ 35 ° C
    		•  Desert day
  • T max  ≥ 30 ° C
    		•  Hot day
  • T min ≥ 20 ° C
    		•  Tropical night
  • T max ≥ 25 ° C
    		•  Summer day
  • T med <15 ° C / 12 ° C
    		•  Heating day
  • T med ≥ 5 ° C
    		•  Vegetation day
  • T min <0 ° C
    		•  Frost day
  • T max <0 ° C
    		•  Ice day
    not uniformly defined: Cold day
    Weather- dependent days
    Cloud cover Bright day
    Cloud cover Cloudy day
    Cloud cover Foggy day
    Humidity / temperature Sultry day
    Precipitation Precipitation day
    Precipitation Rainy day
    Precipitation Hail day
    Precipitation Snow (cover) day
    storm Storm day
    storm Thunderstorm day

    Associated terms

    • Winter: To create a frost zone map, one winter is considered. This lasts from November 1st to March 31st of the following year .
    • Frost period: In road construction , a frost period is a period of days with a mean daily temperature two meters above the ground of less than zero degrees Celsius .
    • Frost intensity: The frost intensity describes the daily mean values ​​of the air temperature during a frost period.
    • Cold period: A cold period is made up of several frost periods. However, only days of non-thorough thawing are allowed between the periods of frost . This is roughly two to three days with temperatures above zero degrees.
    • Frost index: The frost index FI is a measure of the severity of a cold spell. It is the product of the negative daily mean temperature and one day. The unit is ° Cd. According to the definition of the Frost Working Committee (Issue 105, 1994), the frost index is the difference between the maximum and minimum of a temperature curve for a cold period.
    • Frost penetration depth: The frost penetration depth depends on the thermal conductivity of the road structure and the surrounding soil . It can be calculated using a general rule of thumb.
      (for medium severe cold spells)
    • Frost zone borders: The findings from the winter of 1962/63 have shown that Germany can be divided into three frost zones, whereby high altitudes can lie outside this division:
    Zone border Additional layer thickness description
    Zone I. <490 ° Cd +0 cm low risk of frost, low penetration depths
    Zone II 490 <FI <580 ° Cd +5 cm medium risk of frost, medium penetration depths
    Zone III > 580 ° Cd +15 cm great danger of frost, great penetration depths

    State of research

    The frost-proof dimensioning of the road structure in Germany has long been a much discussed topic. Since there have hardly been any similarly severe winters since 1962/63, it is necessary to clarify how the dimensioning can be adapted to the changed climatic conditions, as more material has to be procured, installed and paid for with increasing layer thicknesses . In the states of Brandenburg (Plehm / Kirchner) and Saxony (Roßberg, Bader, Wolf) there were local adjustments as early as the 1990s. Various approaches are also discussed. These include a. the adaptation of the map currently printed in the RStO 2001 , a consideration of frequency and return periods as well as the altitude of the construction sites .

    literature

    • C. Göbel, K. Lieberenz: Manual earthworks of the railways . Eurorailpress, Hamburg 2004
    • Working Committee Frost and Working Group Earthworks and Foundation Engineering: Development and prevention of frost damage to roads . Issue 105, Kirschbaumverlag, Bonn 1994
    • G. Kübler: The influence of weather factors on the risk of frost on roads . Bast , Scientific Reports, Issue 3, Verlag Ernst & Sohn
    • K. Roßberg, E. Bader, M. Wolf: New frost zone map for road construction in the Free State of Saxony . In: Street + Autobahn . 5/96, pp. 264-267
    • Th. Plehm: Approach to the specification of the frost zone map for the state of Brandenburg . Bast , exchange of experience on earthworks in road construction, issue 37, p. 25

    Web links

    Individual evidence

    1. ↑ Note: In contrast to the color markings for the temperature thresholds, the 0 ° C line on the graphic is on the border between turquoise and blue. →  Annual cycle of the graphic (animated)
    2. ↑ a b c d e f g h i j k l m n o Climatological knowledge days in the weather dictionary of the German Weather Service
    3. ↑ Germany : 15 ° C according to VDI 2067 ; Austria , Switzerland , Liechtenstein : 12 ° C according to Usance
    4. ↑ also T med ≥ 10 ° C: day of the main vegetation period