FAQs
1) What does this calculator actually check?
It compares applied tire contact pressure against two limits: adjusted soil bearing capacity and adjusted surface capacity. The governing (smaller) value, divided by the safety factor, becomes the allowable pressure used to judge pass/fail and compute maximum supported wheel, axle, and vehicle loads.
2) Are the soil presets suitable for permits?
They are conservative screening values only. Actual allowable soil pressure depends on site investigation, groundwater, and settlement criteria. For permits or construction design, use geotechnical recommendations or testing. Treat presets as placeholders until project-specific data are available from a qualified professional.
3) How do temperature and repetition affect asphalt?
Asphalt softens with temperature and repeated loading. Warm or hot conditions and frequent traffic reduce the effective surface capacity. The calculator applies reduction factors, highlighting that the same wheel load can be acceptable in cool weather yet unacceptable during prolonged heat or heavy repeated service traffic.
4) Can tire pressure estimate the contact area?
Yes—roughly. Area ≈ Wheel Load ÷ Tire Pressure within one unit system. Real contact shape is not perfectly uniform and sidewall stiffness matters, so this estimate is approximate. If you can, measure the imprint or use manufacturer data for better accuracy than the simple load/pressure ratio.
5) Why include edge and corner modifiers?
Loads applied near slab edges or corners produce higher stresses and deflections than interior loading. Edge and corner modifiers reduce the surface capacity to reflect this vulnerability. If most loading occurs near joints, choose an edge or corner condition to model that more critical scenario realistically.
6) How should I select a safety factor?
Common screening values range from 1.3 to 2.0. Use higher values for uncertain soils, poor construction control, or critical consequences of damage. Lower values may be acceptable with reliable geotechnical data, good quality control, and non-critical use. When uncertain, prefer a more conservative factor.
7) Does thickness or concrete strength change capacity?
They don’t directly enter the pressure check here; thickness and strength record context while the editable surface capacity governs. In practice, slab thickness, reinforcement, base quality, and joint layout influence capacity. If you know a better surface capacity from design, enter it to override the default cap.