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Calcimator

Emergency Response Distance Calculator

Determine initial isolation and protective action distances per the DOT Emergency Response Guidebook.

Inputs

Results

Initial Isolation (ft)

200

Protective Action Distance (miles)

0.7

Protective Distance (ft)3,696
Evacuation Zone (acres)985.2
Downwind Distance (miles)1
Fire Distance Multiplier1
How to Use This Calculator
  1. Select the Material Type (1=Toxic Gas, 2=Flammable Gas, 3=Poison, 4=Corrosive, 5=Oxidizer) based on the ERG guide for the substance involved.
  2. Choose the Container Size (1=Small drums/cylinders, 2=Medium totes, 3=Large tanker/railcar) to reflect the release scale.
  3. Set Time of Day (1=Day, 2=Night) since nighttime atmospheric stability increases downwind hazard distances.
  4. Toggle Fire Involved (1=yes, 0=no) — a fire multiplies distances due to combustion products and pressure releases.
  5. Review Initial Isolation (ft) to establish the hot zone perimeter around the release immediately.
  6. Use Protective Action Distance (miles) and Evacuation Zone (acres) to guide shelter-in-place or evacuation decisions.
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