Recently a timber bridge for heavy traffic is realized in the Netherlands. The 32 meter long bridge spans the A7 highway in Sneek, one of the eleven cities of the world famous eleven cities skating race in Friesland. A second bridge, identical to the one described in the paper, is under construction. Other timber bridges, similar to these, are in the developing phase. Due to durability considerations these bridges cannot be designed without preservation or modification techniques. Since wood preservation is no longer highly appreciated, because of environmental issues, wood modification processes have been developed (and are still under development). However, during modification processes wood temperature rises and, in many circumstances, the strength and stiffness properties are affected. A so-called chemical modification process is chosen for the bridges described. The initial research for determining the influence of the modification process on the strength and stiffness properties is described. Furthermore, the design process in relation to the timber process is outlined.