**10. Conclusion**

Bridges deteriorate and bridges fail. The challenge for bridge owners is how to reduce the rate of bridge deterioration and to prevent bridge failures. Bridge failures are rare but they do occur. The goal of this chapter is to understand the nature of elements that cause deterioration in concrete and steel bridges and the effects these elements have on bridge structural components. The chapter presents an overview of the seven basic types of bridges used world-wide in varying configurations and lengths to meet requirements for specific locations. Components of a bridge, from foundation to superstructure are discussed, of which all bridge components are subject to deterioration in some form. The two primary elements of deterioration are water with deicing chemicals on concrete and steel, and heavy vehicle traffic. To preserve the structural integrity and service life of bridges comprehensive inspection, maintenance, and strong funding programs are required. Inspection emphasis must be placed bridges that are non-redundant and fracture-critical to prevent future failures.

Seven bridge failures and seven research papers are presented in this paper. As became evident in researching bridge failures, all bridge failures have a common characteristic: human error involving flawed designs, a lack of design review and construction oversight, lack of clear lines of authority, coupled with inadequate inspection and maintenance over the service life of the bridge. Bridge failures are preventable. By using the lessons learned in each bridge failure designers, engineers, and inspectors can prevent future bridge failures. Bridge failures are preventable.
