This textbook covers tools and applications in civil engineering systems. It begins by revising the mathematical and statistical background for the adequate formulation of civil engineering problems. Then it examines a series of topics required to understand infrastructure, facilities and transportation networks, and their planning, maintenance, upgrading and expansion. It covers problem definition, model formulation and decision making systems, including optimization, estimation and prediction. The applications deal with some of the challenges that civil engineers will typically encounter during their professional lives, ranging from municipal planning and infrastructure management to transportation analysis. The treatment of the topics is integral. Tools and examples from real life situations are combined to illustrate the use of methods and principles. Students will learn to understand a system, conceptualize a model, analyse it and make decisions or draw conclusions, just as practising engineers do. A final chapter introduces methods for expanding simple models, adding complexity and incorporating uncertainty. Instructors can chose to cover some of the material from the foundation chapters on mathematics and statistics or directly concentrate on the tools and applications.