# An Analysis on Finnish Wooden Bridge Practices
## 5 Discussion  
There is no comprehensive study of the status, applications and future prospects of wood use in bridge construction, reflecting the Finnish professionals' point of view, which emphasizes the unique properties of wood. This article, which also includes a structural design example for dimensioning a girder bridge, aims to fill this gap through expert interviews. Interview results were given according to the following categories: (i) the choice of a wooden bridge and the current situation in Finland; (ii) the challenges of wooden bridge construction; and (iii) future outlook of wooden bridge construction as seen in Table 7. It is believed that this research will support the widespread usage of wood in bridges by contributing to the bridge projects to be developed in the Finnish market.  
\begin{table}
\begin{tabular}{l l c c c c} \hline \hline  & & **Load (kN)** & **Stress (MPa)** & **Strength (MPa)** & **Usage Rate (\%)** \\ \hline Shear & V.y & 29.2 & 0.169 & 3.208 & 5.2 \\ \hline Shear & V.z & 376 & 2.176 & 3.208 & 68.2 \\ \hline Compression & F.c & 86 & 0.332 & 22.917 & 1.5 \\ \hline Tensile & F.t & 64 & 0.247 & 18.333 & 1.4 \\ \hline \multicolumn{5}{c}{**Load (kNm)**} \\ \hline Bending & M.y & 871 & 19.458 & 27.5 & 71.2 \\ \hline Bending & M.z & 11.7 & 14.196 & 27.5 & 52.0 \\ \hline Torsion & T & 3.9 & 0.254 & 5.374 & 4.0 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Stresses, strength, and usage rates of the deck slab [81].  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Corresponding Sub-Sections** & **Highlights** \\ \hline Section 4.1.1 The Choice of a Wooden Bridge and the Current & (a) & The most ideal use of wood is in private road bridges and light traffic bridges. \\ Situation in Finland & (b) & Wood is an ecological and aesthetic material is the most important reason why it is preferred in bridge construction. \\ \hline  & (c) & The disadvantage of wooden bridges was reported as their lack of long-term durability. \\ Section 4.1.2 The Challenges of Wooden Bridge Construction & (d) & Banning the use of creosote as a filler in bridge structures in April 2023 will pose a major problem for wooden bridges in terms of impregnation. \\  & (e) & There are difficulties in the connection details of wooden bridges. \\  & (f) & There may be a further increase in the construction of wooden bridges due to the problems caused by the climate crisis. \\ \hline  & (g) & Concrete and steel, whose prices fluctuate, could gradually be replaced by wood, a renewable material. \\  & (h) & Timber-concrete composite bridges, which are expected to become widespread in the future, have many advantages such as a carbon footprint compared to fully concrete bridges. \\  & Wooden Bridge Construction & (i) & If a good method of protection and long-term durability can be achieved, CLT could open up an opportunity for bridge decks. \\  & (j) & The need for bridge renovation and relocation will increase significantly in the next 10 years. \\ \hline  & (k) & Service limit state is often decisive for the dimensioning of wooden bridges. \\ Section 4.2. A Structural Design & (l) & When dimensioning a bridge, it is important to consider what loads affect each structure. \\  & (m) & Finite Element Method (FEM) is a useful method for making stress calculations, but it is more convenient to calculate local stresses by hand, for example when calculating deck slab. \\ \hline \hline \end{tabular}
\end{table}
Table 7: Corresponding sub-sections and highlights.  
Even though the experts in the survey came from different fields of wooden bridge projects, their viewpoints stated in the interviews were coherent, supportive and complementary. The highlights of Finnish wooden bridge practices are summarized in Table 7.