This spreadsheet calculates the minimum layer thicknesses required for capping and sub-base layers utilised as part of a flexible highway design in accordance with the UK DMRB. These results allow the user to design the thickness of capping and sub-base layers which can be added to a full pavement design package such as the MEDG Asphalt Design Spreadsheet and the UK Flexible Pavement Design Tool.
The spreadsheet includes three different calculations, for capping layer only, for sub-base only and for capping and sub-base designs. The spreadsheets take user input values for the subgrade CBR and layer stiffness, then they calculate the required capping and/or sub-base layer thicknesses to comply with the UK DMRB for highway loadings.
The spreadsheets also include unique tools allowing the user to see the effects of different subgrade CBR values and layer stiffness, without re-entering any of the input data. This makes it easy for the designer to quickly calculate the required layer stiffness for a particular thickness, or see what the effects of increasing the subgrade CBR would be.