• trackbed
• reinforcement
• transition
• track
• ground improvement
• micropiles
• railway
• geogrids

Transitions between different track support conditions can pose major problems for railways. These zones are located along tracks with different support stiffness, for example at the transition between soft soil and settlement free zones, or at the run on/off to structures such as box culverts or bridges. Problems with transitions on existing lines can cause poor track quality and subsequent excessive maintenance requirements or potential issues at structures due to increased dynamic interaction. Problems can be exacerbated by fluctuating environmental conditions and increased linespeeds. This thesis presents a case study of 13 sites in the UK, and analyses existing data sets to better understand the causes, frequency and nature of deterioration. Operational transition sites and sites planned for remediation have been identified to better understand the performance of the various designs constructed. Transition solutions used comprise geogrids, polymers and micro piles. By analysing the cases in which the treatment was successful or not, it was possible to obtain important information about the behavior of different transition zones and on the treatment used.