**3. Bridge failure statistics: Where? Why? When?**

Collapse of bridge structures is one of the worst infrastructural disasters. For example, **Figure 2** shows several spectacular bridge catastrophic collapse cases in the world. It has been reported that the most bridge collapses occurred in North America and Europe, especially in the USA (see **Figure 3**). Extreme conditions under natural hazards, design error and wrong assumption in load combination or ground condition, overloading, impact of vehicles, poor workmanship and inadequate maintenance action, vandalism (e.g., fire and explosion), deterioration, corrosion and fatigue in materials, and limited knowledge due to unknown phenomena are possible causes of bridge collapse. For the sake of clarity, **Figure 4** shows a summarization of the causes of the bridge failure in China. Bridge failure can be occurred both during the service life of the infrastructure or in the construction stage. For example, **Figure 5** tries to illustrate the number of bridge collapses and casualties between 2009 and 2018 [31]. It should be noted that it was difficult to find out more about the prevalence of bridge collapse in Africa, Asia, and South America. **Figure 6** lists a variety of factors, which are essentially not considered in the calculation of the probability of failure.

For better understanding, **Figure 7** presents the catastrophic bridge failures from 1967 until now in the U.S. along with the cause of failures (e.g., corrosion, scour, human error (i.e., design error and construction error), fire, etc.), number of injuries and fatalities.

*DOI: http://dx.doi.org/10.5772/intechopen.104905 Introduction to Monitoring of Bridge Infrastructure Using Soft Computing Techniques*

#### **Figure 2.**

*Examples of bridge catastrophic failure. (a) Tacoma Narrows Bridge in Washington, USA: (Left) opened on July 1, 1940 and (Right) collpased on Novermber 7, 1940 [23, 24]. (b) Hanshin Expressway bridge in Kobe, Japan: (Left) before and (Right) after collapse on January 18, 1995 [25, 26]. (c) I-35W Bridge in Minneapolis, USA: (Left) before and (Right) after collapse on August 1, 2007 [27]. (d) Morandi bridge in Genoa, Italy: (Left) before and (Right) after collapse on August 14th 2018 [28, 29]. (e) Nan Fang'ao bridge in Taiwan: (Left) before and (Right) after collapse on October 1, 2019 [30].*
