As a rule, the design of our bridges is based on the new Swedish National Road Administration's TK Bro/TR Bro. In all projects, inspections are carried out for structural strength and deflection, and the vibration characteristics of pedestrian and bicycle bridges are also examined. Deflection must not exceed 1/400 of the bridge span width. As far as vibrations are concerned, natural frequencies must be more than 3.5 Hz and vertical acceleration less than 0.5 m/s². According to the standard, pedestrian and bicycle bridges must be capable of withstanding traffic loads of 4 kN/m², or a refuse collection vehicle of 120 kN (axle loads 80+40 kN),  while road traffic bridges must be designed to cope with various types of traffic load case. The design load is usually Equivalent load type I which consists of three 250 kN axle loads and a uniformly distributed load of 4 kN/m². The fatigue load is rarely dimensioned for wooden constructions.


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