Using Engineering Survey Techniques for the Tonkolili Railways Project

SUMMARY Tonkolili Railways Project is the biggest development project in Sierra Leone since the end of the civil war 10 years ago. It is the construction of 120 km of new railway from Lunsar to Tonkolili council. Three companies are principal contractors, Dawnus, Basil Reed and WBHO with AML being the principal client. The rail will be used to transport the iron ore from Tonkolili to Pepel port. The survey operations were taken two stages: - First stage when the surveyors went on field to stake out the center line of the new rail. An autonomous position was used to stake out the coordinates, and a D6 Cat dozer to cut through the vegetation growth. - Second stage – multiple surveys and stake out operations involved in construction. Establishing GPS control points and office post processing, original survey and stake out. Calculate and stake out alignment (horizontal and vertical), with straight, transitions and curves. Also calculate top of batter cut positions and toe of batter fill positions with slope distances and fill heights. A complete cross section survey every 20m taken at the start of the job and a weekly survey taken at work locations as job progressed. Volumes calculated from these surveys. The main problems have been to establish new control points in the desired map projections and geoid model. I work for Dawnus, a Welsh civil engineering company, responsible for 50Km of new rail construction and 70Km of rail refurbishment. The engineers are all British and the surveyors are from Romania, who work closely together with Sierra Leone engineers. So there is three quite different cultures that mix together and have to make it work for the project to be a success. Many villages have to be passed and everyday the surveyors got involved with local people. So again there is a big mix of cultures and sometimes the challenge can be difficult, but most of the time it is worthwhile.