Hot-mix asphalt (bituminous) railway trackbeds: In-track tests, evaluations, and performances - A global perspective: Part I - Introduction to asphalt trackbeds and international applications and practices

The railway industry continues to emphasize the importance of developing innovative trackbed design technologies for both heavy tonnage freight lines and high-speed passenger lines. The purposes are to achieve high levels of track geometric standards for safe and efficient train operations while minimizing long-term track maintenance costs and extending track component service lives. During the past several decades designs incorporating a layer of asphalt paving material, similar to a highway pavement asphalt base layer, as a portion of the railway track support structure have steadily increased until it is becoming a common practice. In this, the first part of a three part paper, factors are discussed that are considerations in the design phase. Illustrations of trackbed/roadbed components, construction phases, and finished projects are presented for various applications in several countries, including Italy, Austria, and France. Part II describes applications in the United States. Part III presents performance-based tests and analyses.