Task 1: Giving a brief description of terminologies used in setting out buildings
i) Plan measurement – this is a plan that seeks to extract markers and points of reference which will be used as a guide during the construction of new buildings. The markers mostly are staked out in accordance to the selected coordinate system of a particular building project.
ii) Check lines – check lines connect the main station and a subsidiary station on the opposite site. They are important because they check the accuracy within subsidiary station and the main station. These check lines are sometimes called group lines (Bharadwaj, 2012)
iii) Profile board – it is a plate or a board that is cut into a certain required pattern that is normally used to fix dimensions or shapes during the set out of a building. When using a profile board, the basic rule is basically to place quite a number of boards that will show exact level one meter above the on going construction levels that have been completed.
iv) Optical square – this is a device that uses pentaprism in refracting and reflecting a beam during construction. Normally it must be paired to function well during surveying.
Task 4 Challenge task
Explain the constraints on the positioning and accuracy of profile boards on site and their use.
Your explanation should also include the details that can be transferred or marked onto the profile boards
Answer;
Accuracy sometimes is brought about by wide spacing which may be done while placing profile levels. The wide spaces may result into severe errors that may cause big cracks. To overcome this constraint, engineers need to transfer exactly one profile board level to another so as to ensure the same level have been reached by the profiles. Measurement should be done from down to up of the horizontal level and then another profile board is set to so as to attain a certain level differences between the two profiles. The slope should be measured between the two boards that are fixed so as to the one that is higher or lower is determined.
Bad weather is another constraint that may affect profile board method during construction. Where there is ground movement a severe damage of the project may occur. This will be overcome by knowing the line where the profile will be taken and this should be inspected and marked before a survey is done. Rod reading should be done at all full stations at every major break in the slope (Certified Technician Program Training Manual, 2012). When the ground is soft there will be a challenge in laying profile boards especially when excavation is done near the profiles. The challenge can be overcome by fixing another profile board among the two adjustable boards already fixed. The third profile is known as a traveler. The traveler controls the levels that have been done already (Profile Board Method, n. d)
The safety precaution that should be taken is to use profiles that are adjustable, moved or locked in positions that may be desirable. A profile board that is required to be long lasting long should be made using strong thin steel plates that are welded to metals with short lengths which are able to slide down and up and also clamped to metal rods. To take further precautions, the profile rods should be painted or marked with white and red paints so as to be seen or identified easily during a set out.
Work Cited
Bharadwaj, N. 2012. Define base line check line tie line and detail lne-Dec 2012. Eduladder. Banglore. Retrieved from; https://eduladder.com/viewquestions/610/Define-base-line-check-line-tie-line-and-detail-line-Dec-2012
Certified Technician Program Training Manual, 2012.ConstructionProcedures Part I. retrieved from; http://in.gov/indot/files/ED_ConstructionProcedures_Part1.pdf
The Profile Board Method, n. d. Setting out using the profile board method. Retrieved from; http://www.ruralworks.com/reports/profileboard/ProfileBoard.html
