The development of pavement rehabilitation design guidelines for increasing the allowable axle load from 100 kN to 115 kN

The road network in Hungary had to be improved and reconstructed due to the mutual EU agreement to increase the then allowable 100 kN axle load to 115 kN. This requirement was a challenge on an aged road network, where the pavement layers were designed and built to a lesser frequency and amplitude of vehicle loading. The Instrument for Structural Policies for Pre-Accession (ISPA) was launched to assist the candidate countries with this issue. This paper provides a summary of the development of a series of guidelines for road pavement rehabilitation design in Hungary. The complex problem of the pavement structural design in a semi-empirical system is discussed; the EU does not provide harmonised standards for pavement design purposes. Also, the paper outlines how to incorporate existing asphalt layers prone to plastic deformation into the rehabilitated pavement structure, while maintaining a low risk of future distresses. The guidelines were developed on a series of case studies of an overall length of 300 km. FWD tests and wheel tracking tests combined with visual inspections provided the basis for the work. Using this approach it was possible to develop a series of guidelines for cost-effective pavement rehabilitation design.