Quantifying the uncertainty in tribometer measurements on walkway surfaces

Area of Science:

• Materials Science
• Metrology
• Civil Engineering

Background:

• Accurate walkway surface friction is crucial for pedestrian safety.
• Existing friction measurement methods may not fully capture total uncertainty.

Purpose of the Study:

• To quantify the amount and sources of uncertainty in walkway surface friction measurements.
• To determine the minimum uncertainty for reliable friction assessments.

Main Methods:

• Two tribometer models (Slip-Test Mark IIIB, English XL) were used.
• Four users performed 12 measurements each on four different surfaces using four units of each model.

Main Results:

• User, unit, and sample interactions explained 51-82% of measurement variance.
• Single-user variance calculations underestimate total uncertainty.
• Minimum uncertainties were ±0.064 (Mark IIIB) and ±0.072 (XL) for 95% confidence.

Conclusions:

• Walkway friction measurements are less accurate than typically reported.
• Standard deviation alone does not represent the full measurement uncertainty.
• Reporting comprehensive uncertainty is vital for accurate pedestrian safety evaluations.