Hurricane Evacuation Time Calculator

ANA›Life Services Authority›National Calculator Authority›Hurricane Evacuation Time Calculator

.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }

Hurricane Evacuation Time Calculator

Estimates total evacuation time considering distance to safety, population size, available road capacity, vehicle occupancy, and storm approach speed.

Distance to Safe Zone (miles)

Evacuating Population (people)

Number of Evacuation Lane-Miles Available

Average Vehicle Occupancy (people/vehicle)

Evacuation Compliance Rate (%)

Storm Approach Speed (mph)

Current Storm Distance from Zone (miles)

Contraflow Implemented?

No Yes (+40% capacity)

Hurricane Category

Category 1 (minor congestion factor) Category 2 Category 3 Category 4 Category 5 (major congestion factor)

Calculate Evacuation Time

function hurCalc() { var distance = parseFloat(document.getElementById('hur-distance').value); var population = parseFloat(document.getElementById('hur-population').value); var lanes = parseFloat(document.getElementById('hur-lanes').value); var occupancy = parseFloat(document.getElementById('hur-occupancy').value); var compliance = parseFloat(document.getElementById('hur-compliance').value); var stormSpeed = parseFloat(document.getElementById('hur-storm-speed').value); var stormDist = parseFloat(document.getElementById('hur-storm-distance').value); var contraflow = parseFloat(document.getElementById('hur-contraflow').value); var catFactor = parseFloat(document.getElementById('hur-category').value); var resultDiv = document.getElementById('hur-result');

// --- Validation --- if (isNaN(distance) || distance Please enter a valid distance to safe zone (> 0 miles).'; return; } if (isNaN(population) || population Please enter a valid evacuating population (> 0).'; return; } if (isNaN(lanes) || lanes Please enter a valid number of lane-miles (> 0).'; return; } if (isNaN(occupancy) || occupancy Vehicle occupancy must be at least 1.'; return; } if (isNaN(compliance) || compliance 100) { resultDiv.innerHTML = 'Compliance rate must be between 1 and 100.'; return; } if (isNaN(stormSpeed) || stormSpeed Please enter a valid storm approach speed (> 0 mph).'; return; } if (isNaN(stormDist) || stormDist Please enter a valid storm distance (> 0 miles).'; return; }

// --- Core Calculations ---

// Step 1: Number of vehicles needing to evacuate // Vehicles = (Population × Compliance%) / Occupancy var evacuatingPeople = population * (compliance / 100); var vehicles = evacuatingPeople / occupancy;

// Step 2: Road capacity (vehicles per hour) // Standard highway capacity: ~1800 vehicles/lane/hour (HCM standard) // Adjusted by contraflow multiplier var baseCapacityPerLane = 1800; // vehicles/lane/hour (Highway Capacity Manual) var totalCapacity = baseCapacityPerLane * lanes * contraflow; // vehicles/hour

// Step 3: Clearance time (time to move all vehicles through the network) // ClearanceTime (hrs) = Vehicles / TotalCapacity × CategoryFactor var clearanceTime = (vehicles / totalCapacity) * catFactor;

// Step 4: Travel time (time for last vehicle to reach safe zone) // Average evacuation speed under congestion: ~35 mph (FHWA evacuation studies) // Adjusted for category congestion var baseEvacSpeed = 35; // mph var effectiveSpeed = baseEvacSpeed / catFactor; var travelTime = distance / effectiveSpeed;

// Step 5: Total evacuation time // TotalTime = ClearanceTime + TravelTime // (clearance drives the queue; last vehicle still needs to travel) var totalEvacTime = clearanceTime + travelTime;

// Step 6: Time until storm arrival var timeToStorm = stormDist / stormSpeed;

// Step 7: Safety buffer var safetyBuffer = timeToStorm - totalEvacTime;

// Step 8: Recommended evacuation order time (issue order this many hours before storm) // Add 2-hour preparation/mobilization time (FEMA standard assumption) var prepTime = 2.0; var orderLeadTime = totalEvacTime + prepTime;

// --- Format helpers --- function fmtHrs(h) { var hrs = Math.floor(h); var mins = Math.round((h - hrs) * 60); if (mins === 60) { hrs++; mins = 0; } return hrs + ' hr' + (hrs !== 1 ? 's' : '') + ' ' + mins + ' min'; }

function fmtNum(n) { return Math.round(n).toLocaleString(); }

// --- Status assessment --- var statusColor, statusMsg; if (safetyBuffer >= 6) { statusColor = '#27ae60'; statusMsg = '✅ Sufficient time — evacuation is feasible with a comfortable safety margin.'; } else if (safetyBuffer >= 2) { statusColor = '#f39c12'; statusMsg = '⚠️ Marginal — evacuation is possible but the safety margin is tight. Issue orders immediately.'; } else if (safetyBuffer >= 0) { statusColor = '#e67e22'; statusMsg = '🚨 Critical — very little margin. Evacuation must begin NOW.'; } else { statusColor = '#c0392b'; statusMsg = '❌ Insufficient time — storm may arrive before full evacuation completes. Shelter-in-place may be necessary for some.'; }

// --- Output --- resultDiv.innerHTML = '### Evacuation Time Estimate ' + '' + 'Evacuating People' + fmtNum(evacuatingPeople) + ' people (' + compliance + '% of ' + fmtNum(population) + ')' + 'Vehicles to Evacuate' + fmtNum(vehicles) + ' vehicles' + 'Total Road Capacity' + fmtNum(totalCapacity) + ' vehicles/hour' + 'Network Clearance Time' + fmtHrs(clearanceTime) + '' + 'Travel Time to Safe Zone' + fmtHrs(travelTime) + ' (at ~' + effectiveSpeed.toFixed(1) + ' mph effective)' + '⏱ Total Evacuation Time' + fmtHrs(totalEvacTime) + '' + 'Time Until Storm Arrives' + fmtHrs(timeToStorm) + '' + 'Safety Buffer' + (safetyBuffer >= 0 ? '+' : '') + fmtHrs(Math.abs(safetyBuffer)) + (safetyBuffer ' + 'Recommended Order Lead TimeIssue evacuation order at least ' + fmtHrs(orderLeadTime) + ' before storm landfall' + '' + '' + statusMsg + ''; }

#### Formulas Used

1. Evacuating Vehicles: Vehicles = (Population × Compliance%) ÷ Vehicle Occupancy

2. Total Road Capacity (vehicles/hour): Capacity = 1,800 veh/lane/hr × Lane-Miles × Contraflow Multiplier (1,800 veh/lane/hr is the Highway Capacity Manual standard for freeway capacity)

3. Network Clearance Time (hours): Clearance Time = (Vehicles ÷ Capacity) × Hurricane Category Factor

4. Travel Time (hours): Travel Time = Distance ÷ Effective Speed Effective Speed = 35 mph ÷ Category Factor (35 mph is the FHWA-observed average evacuation speed under congested conditions)

5. Total Evacuation Time: Total = Clearance Time + Travel Time

6. Safety Buffer: Buffer = (Storm Distance ÷ Storm Speed) − Total Evacuation Time

7. Recommended Order Lead Time: Lead Time = Total Evacuation Time + 2 hrs (mobilization/preparation)

#### Assumptions & References

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