Tunnels environments are characterized by dust, humidity, and absence of natural light. Artificial and natural impacts, change in load criteria, or the simple effect of ageing, make tunnels require inspection and maintenance. These operations are commonly performed by human workers taking time and expertise without guarantee quality control. Robotic tunnel inspection and maintenance (RTIM) introduces high productivity, quality and repetitiveness. This paper describes the current trends in the subject, and introduces new technologies such as scenario modeling, robotic platforms, image and ultrasound sensors, control algorithms and decision making strategies. Additionally, the result of several recent and ongoing projects will be presented.