Interest in long-term durability and sustainability of bridges has challenged the development of modern bridge management. The structural condition and performance of bridges have drawn much economic and engineering attention. In comparison, the effective functionality of bridges is another major sustainability concern, affecting their safety, mobility, and life span. To reach cost-effective planning and systematic management, consideration of functionally obsolete bridges is essential. This article discusses the critical aspects of evaluation, traffic mobility, and congestion cost of functionally obsolete bridges. A methodology was developed for bridge functional obsolescence evaluation. Actual bridge inventory and conditions databases were studied to compile practical data that generates focused insight for decision-making. A forecast was developed to predict the number of functionally obsolete bridges in the future. Practical cost components of traffic congestion were discussed to facilitate consideration of better original design and construction versus reassignment design and work. The resulting study is practical for transportation agencies, officials, and researchers to support sustainable bridges by planning financial resources, management policies and strategies, design methods, and implementation practices.