What critical environmental conditions lead to accelerated decay in timber bridges?

Critical environmental conditions that lead to accelerated decay in timber bridges include high moisture levels, warm temperatures, and exposure to oxygen. High moisture levels, particularly above 20%, create a favorable environment for the growth of decay fungi. Warm temperatures accelerate the metabolic activity of these fungi, increasing the rate of decay. Oxygen is also essential for fungal growth, so well-ventilated areas can still experience decay if moisture and temperature are conducive. Cycles of wetting and drying can also promote decay by creating conditions that favor the growth of different types of fungi. In addition, exposure to sunlight can degrade the surface of the wood, making it more susceptible to decay. Combining these environmental conditions creates an ideal environment for rapid and extensive decay in timber bridges.