Hardwood has been the preferred material for railway sleepers and maintenance work on existing timber sleeper track continued to be provided by hardwoods. Over the past decade, it has been increasingly difficult to get good quality hardwood in quantities to keep up with demand. This trend is set to continue and will become critical within the foreseeable future, hence the need to develop a sleeper product made from renewable resources. A collaborative effort between the Centre of Excellence in Engineered Fibre Composites (CEEFC) and Austrak Pty Ltd has developed an optimised fibre composite timber replacement turnout sleeper (TRTS). The TRTS is new type of sleeper developed for replacing deteriorated hardwood sleepers in railway turnouts where larger and longer timber of a higher grade is required. The building block of this alternative sleeper material is a new generation composite sandwich structure made up of glass fibre reinforced polymer skins and high strength core material produced by LOC Composites Pty Ltd. A trial production run was conducted which manufactured the first TRTS prototypes. Field trials and in-service performance evaluation showed that the TRTS perform well under actual service conditions and showed compatibility with the existing timber turnout sleepers. It has similar usability and design characteristics to that of hardwood sleepers. In addition, this sleeper material could provide longevity of 50 to 100 years, and could become a carbon sink as well as being less of a pollutant than other alternatives.