Precision Standards

Both Schematic and Plans, Specifications, & Estimates (PS&E) surveys shall follow the same precision standards. These standards are below:
  • Horizontal accuracy error allowance:
    • Bridges and other roadway structures: less than 0.1 feet.
    • Utilities and improvements: less than 0.2 feet.
    • Cross-sections and profiles: less than 1 foot.
    • Bore holes: less than 3 feet.
  • Vertical accuracy error allowance:
    • Multi-phase bridges: less than 0.02 feet.
    • Single-phase bridges and other roadway structures: less than 0.04 feet.
    • Utilities and improvements: less than 0.1 feet.
    • Cross-sections and profiles: less than 0.2 feet.
    • Bore holes: less than 0.5 feet.
  • Spatial density requirement:
    • Manmade features: Maximum distance between measurements is 25 feet.
    • Natural features: Maximum distance between measurements is 50 feet.
It is the responsibility of the surveyors to understand the capabilities of the measurement devices used for the survey. Recommended practices and procedures are provided in the
TxDOT Surveyors’ Toolkit
. TxDOT District Survey Coordinators shall randomly check data using the recommended practices and procedures to ensure compliance. The surveyor is responsible for reacquiring all data for a survey that does not satisfy the random checks.