Surveying, Drawing and Computer Applications in Structural Engineering
Domain overview
This section tests surveying for setting out and level control, plus drawing and CAD/BIM production. The exam expects correct instrument arithmetic, coordinate handling, scale interpretation and disciplined drawing revision.
Core rules
- Height of instrument HI = known RL + backsight; new RL = HI − foresight or intermediate sight.
- Reduce levels in a level book and check misclosure against permissible limits; always identify change points.
- Coordinates and bearings must use a consistent north and units; traverse adjustment should preserve geometric closure.
- CAD drawings need layers, lineweights, scales and title blocks; BIM models require coordinated levels, grids and clash review.
Worked example
A benchmark has RL 100.000 m. A backsight of 1.250 m is read on it, so HI = 100.000+1.250 = 101.250 m. A foresight of 2.100 m is read on a point, giving RL = 101.250−2.100 = 99.150 m. If the instrument is moved, take a backsight on a stable change point to establish the new HI; do not carry the old HI forward. Record the arithmetic in the level book and check the closing error against the specified tolerance.
Traps
Adding a foresight instead of subtracting it, mixing staff readings in millimetres with metre RLs, ignoring scale when measuring from a PDF, and issuing drawings without revision control.