Week 5 Flashcards
(21 cards)
What is the general acceptance criterion for levelling between benchmarks? ±5mm.
What are the two methods of setting out a point position? 1. Setting out from reference line and offsets. 2. Setting out from polar coordinates using an angle from a reference bearing and a distance from a reference point.
What are the steps for setting out using polar coordinates? 1. Set up total station at Point 1 and sight at Point 2.
- Measure distances xA and xB along line 1-2.
- Set up at A’
sight at Point 1
- Set up at B’
sight at Point 1
What are sight rails? Horizontal timbers that define the plane of the finished works at a level above the ground.
What is a traveller in the context of vertical control? A portable sight rail with a vertical support
used to check excavation depth.
What is the process for setting out gradients using sight rails? The same process as setting out along a horizontal plane
but the sight rails are called batter rails.
What is the purpose of batter rails? They are used for setting out slopes or drainage.
What is a laser level and its function in large earthwork projects? A laser level is fixed to a tripod
levelled
What is chainage in road construction? Chainage indicates distance along the road measured from the starting point of the scheme.
What are the basic parts of a circular horizontal curve in road design? Two straights meet at the point of intersection I
with a circular arc running between them
What is the deflection angle in the context of circular curves? The angle θ between the tangents at the points of intersection.
What is the significance of accurate positions in machine control for road curves? Accurate positions ensure that the curves are set out correctly according to the design model.
What is the role of a total station in setting out procedures? It is used to measure distances and angles for accurate positioning of points on the ground.
What is the importance of knowing the coordinates of set up stations in field procedures? They are essential for accurate measurements and setting out of the project.
What is the EDM function of a total station used for? It is used to measure distances accurately during the setting out process.
What should be done before using a traveller for excavation checks? Both profiles should be in place to ensure accurate depth measurements.
What is the purpose of profile boards in road construction? They indicate the finished level of the road and help guide excavation.
How is the height of sight rails determined? It is set to give the correct excavation depth based on the required finished level.
