The initial skid resistance of new surface layers is often smaller than after some months under traffic. This is mainly due to the bituminous film covering all aggregates surfaces. This phenomenon is particularly observed by layers with highly proportioned polymer modified bitumen. According to this problem, one of the conclusions of the VSS research work 1999/298 was the following: "In order to work against uncertainty concerning initial skid resistance of new surface layers, an acceptance test on basis of texture measurement is to be preferred to dynamic measured skid values”.
The goal of the research project consists of developing a methodology for the acceptance test and evaluation of the skid resistance of new surface layers. Acceptance tests should be done on the basis of macro texture values. The applicability of existing foreign methods is to be examined and if necessary developed further for the Swiss environment. The results of the research work form the basis for the appropriate part of the new Swiss standards SN 640'920 "Characteristics of the road surface - Requirements".
Following steps were provided during the project:
- Literature review, collecting existing documents and contacts with the "developers" of the methods used in France (LCPC: Michel Boulet, Michel Gothier, Minh Tan Do) and in England (TRRL: Ramesh sinhal, Helen Viner, Peter Roe)
- Analysis and summary of the information gathered, and assessment of the applied data bases and the selected rating scale
- Review of the basics and methods in terms of their application in Switzerland
- Formulation of rules and recommendations for a possible application of acceptance tests based on texture measurements in the CH-normalization.
Rules and recommendations for a possible application of acceptance tests based on texture measurements in the CH-normalization are results of the project.
One of the further results of the project is the collection and assessment of the skid resistance of new layers and thus improve road safety during this (for grip) critical stage.
The immediate beneficiaries of clearly defined conditions of traffic safety in the area of macro texture are all road users in the first place. On the other hand, precise conditions of acceptance of the outer layers are produced for both the building owners as well as for construction companies today lack a "standard security".