This textbook introduces probabilistic and statistical modelling to risk management and decision making in the face of uncertainty. It then applies this especially to transportation systems. From basic concepts and methods in probability and statistics (descriptive and inferential), it develops to cover more advanced topics in discrete choice and count econometric models particularly for transport systems and frameworks for risk analysis and management. It takes a problem driven approach, where the materials are explained highly intuitively and supported by examples and cases from transportation systems and more widely from civil and environmental engineering. Concepts are related to practice and to professional skills so that real-world problems are explored in a structured way. The problem formulation and solving processes are systematized, but without heavy mathematics. It suits students at undergraduate and graduate level as well as serving as a guide to core techniques for practising engineers.