$16\mathrm{.}9$ "The construction of a bridge involves a myriad of considerations, from structural integrity to environmental impact. Discuss the key factors that civil engineers must take into account when designing and building a bridge over a major river. How does the choice of materials, construction methods, and site location influence the overall success and longevity of the bridge? Additionally, analyze the role of sustainability in bridge construction and how modern engineering practices aim to minimize environmental impact while ensuring structural resilience and safety."