Orsaker till halka på cykelvägar och beläggningens inverkan: en beskrivning av kunskapsläget

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This report is a literature review of the state of knowledge to understand the reasons for slipperiness on bicycle paths. The effect of texture on friction and slip risk and environmental impact is described. One of the main aims of the report is to present knowledge and needs around the friction and slip resistance of different types of surface courses under different conditions in cycle speeds up to 40 km/h. The slip risk is determined among others by the friction between the tire and the road surface. There are many factors that affect this friction, for example, the road surface's property, vehicle speed, tyre characteristics and the environment. This report focuses on the road surface's properties and meteorology (mainly temperature and humidity) and not on the bicycle or its component properties. The texture of the road surface is an important parameter when it comes to slip. The texture is divided into three wavelength ranges: micro, macro, and mega textures. Primarily, it is micro-texture and macro-texture that affect the friction of bicycles. In practice, the tire and the cycle path are rarely two clean surfaces that meets. Often, slip also occurs when the surface is dirty, water, snow and ice act as a friction-reducing layer between the wheels and the surface. Loose gravel also gives rise to slipping risk.

There are friction requirements for walking and cycling paths, although friction measurements are rarely carried out. Existing requirements in Sweden for surface course, including walking and cycling routes, are that the average friction number must not be less than 0.50 over a 20 meter long distance. Friction measurement can be done with PFT (Portable Friction Tester) as this hand-held instrument correlates well with the standard method Road (SAAB) Friction Tester which cannot be carried out on a bicycle path.

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