Theory of Errors & Plane Table Surveying
Theory of Errors, Occurrence of Error- Imperfection in Instruments, Environmental Condition, Human Limitations & Carelessness, Type of Error– Gross Errors or Mistakes, Systematic or Cumulative Errors, Accidental or Random errors, Important Terminology- Precision, Accuracy, True Value, True Error, Most Probable Value (M.P.V), Principle of Least Square, Residual Error. Law’s of Weights, Probable Error– Probable Error in Single Measurements, Probable Error in Mean (MPV), Probable Error of Single Measurement of Weight, Error In Computed Result.
Plane Table Surveying, Accessories Used in Plane Table Surveying- Plane Table Board, Alidade (for orientation), Tripod (for stand), Level Tube/ Spirit Level (for leveling), Compass (for orientation), Plumbing Fork (for centering), Procedure, Setting up the Plane Table- Centering, Levelling, Orientation: Orientation with a Trough Compass, Orientation by Back-Sighting, Resection. Method Of Plane Table Survey– Radiation Method, Traversing Method, Intersection Method, Resection Method- Compass Method of Resection, Back Ray Method of Resection, Two Point Problem of Resection, Three Point Problem of Resection.
Topics
Compass is a survey instrument used for the measurement of horizontal angles and the bearing of a line of sight.Surveyor Compass and Prismatic Compass are discussed in detailed.
In setting out of circular curve we details discuss offsets from long chord, offset from tangent, offset from chord produced in linear method & tape & theodolite/rankine method / tangential / deflection angles, two theodolite method, tachometer method in angular method.