>> On the first page of David Billington's seminal book, "The Tower and the Bridge", he writes quote, civilization is civil works and insofar as these deteriorate so does society. Hello. I'm Maria Garlock, professor of civil engineering at Princeton University. This course is essentially about civil works, about civil engineering, and in particular about structural engineering. In David Billington's quote, the meaning of deteriorate is not just a reference to the aging process but also the ideals and attitudes with which we design our civil works. If these deteriorate so does society. Although he wrote these words more than 30 years ago, they are more relevant today than ever. This is a critical time for civil engineers since civilization is facing a perfect storm of challenges. For example, over 70% of the world's population is expected to live in cities by the year 2050. In addition to increasing population densities, other challenges include limited natural resources, aging infrastructure, increase in load demands such as in tense and heavy traffic and extreme weather, and natural and human induced hazards such as earthquakes and terrorist acts. Engineers must design our civil works with these considerations and typically within the context of severe financial constraints. At the same time, in regards to buildings and bridges, elegance must be part of the fabric of design since these civil works visually dominate the landscape. I have a question for you. What do you think a civil engineer does? This course illustrates how some of the best engineers of the past and present have faced challenges in their design of civil works. In this course, I will focus on bridges. In the future, I will speak of buildings and long span roof structures. The foundation for this course is a scholarship with my colleague, Professor David P. Billington, who has defined post-Industrial Revolution structures that are efficient, economical and elegant as a new art form called structural art. Structural art has three ideals and each of these can be related to the ideals of the built urban environment. Efficiency is the conservation of natural resources. Economy is the conservation of public resources. And elegance is the creation of an attractive urban environment. Efficiency and economy can be considered the ethic of the engineer and elegance the art of the engineer. Each of these three ideals can be matched to a dimension or perspective that can be used for measuring structural art. The scientific dimension is measured by efficiency. It is based on calculations that reveal quantitatively the efficiency of form and the quantity of material used. This measurement is done with consideration of achieving adequate levels of safety. The social dimension is measured by economy. These large built works must be supported through public taxation or private commerce, both of which are influenced by the societal context including politics. And finally, the symbolic dimension is measured by elegance. Here the measure is mostly subjective. However, we can examine how artists such as painters and poets are stimulated by these large utilitarian objects. We can also examine how society embraces such works, many of which become not only an icon of the city but of the country. Tell me what you think. Post a picture of a bridge that you consider to be structural art. After that, since I will next speak of engineering versus architecture, tell me what is the role of an engineer and the role of an architect in the design of bridges? What do you think?