Convoy Speed Calculator
Calculate column speed, length, and pass time from vehicle count, spacing, and road conditions for convoy planning.
About this calculator
This calculator estimates convoy movement timing and column geometry from vehicle count, spacing, and road conditions. Convoy speed is a flat 40 km/h base multiplied by a road-condition factor ranging from 1.0 on paved highway down to 0.3 on unimproved roads (lines 14-19) -- nothing else in this calculator changes convoy speed, not vehicle count, length, spacing, or route distance. Column length is unrelated to road condition; it is purely the sum of each vehicle's length plus the spacing between vehicles, using one fewer gap than vehicle count (line 9).
Travel time divides route distance by convoy speed (line 26), and total time adds planned halt time -- halts multiplied by halt duration, converted to hours (lines 27-28) -- on top of travel time. Pass time is how long the whole column takes to clear a fixed point, derived from column length and convoy speed (line 31), and closure time adds that pass time to travel time to estimate when the last vehicle arrives after the first departs (line 34). Because road condition alone sets speed, and vehicle count and spacing alone set column length, planners can size vehicle intervals and account for road quality as two nearly-independent levers on this calculator.
Safety Notice
This calculator provides estimates only. Always follow manufacturer guidelines, industry standards, and applicable safety codes. Incorrect application of these calculations could result in injury or property damage. When in doubt, consult a qualified professional.
Inputs
Results
Convoy Speed
30 km/h
Total Time (incl. halts)
3.2 hrs
How to Use This Calculator
- Enter the number of vehicles in the convoy and average vehicle length (meters).
- Set vehicle spacing (meters) — typically 50–100m on roads, 25m in urban areas.
- Select road condition: Paved Highway, Secondary Road, Improved Dirt, or Unimproved.
- Enter route distance and planned halts to calculate travel and total arrival time — column length depends only on vehicle count and spacing, not route distance.
- Use column length and speed outputs for route clearance and traffic control point planning.
What each input means
- Number of Vehicles
- Total number of vehicles in the convoy.
- Average Vehicle Length
- Average length of vehicles in the column.
- Vehicle Spacing
- Distance between vehicles (25-100m normal, 100-200m tactical).
- Road Condition
- Quality of the route road surface.
- Route Distance
- Total route distance from SP to RP.
- Planned Halts
- Number of planned rest or refueling halts.
- Halt Duration
- Average duration of each planned halt.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersNumber of Vehicles = 20, Average Vehicle Length = 7, Vehicle Spacing = 50, Road Condition = 1 = 7 input(s) provided
- Calculate Convoy SpeedConvoy Speed30 = 30
- Calculate Total TimeTotal Time3.2 = 3.2
- Calculate Column LengthColumn Length1090 = 1090
- Calculate Travel TimeTravel Time2.7 = 2.7
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Does adding more vehicles to the convoy slow it down?
No. Convoy speed is set entirely by the road-condition factor times a 40 km/h base (lines 14-19); vehicle count, vehicle length, and vehicle spacing never enter that formula. More vehicles lengthen the column (line 9) and therefore increase pass time and closure time, but the convoy's travel speed itself stays the same regardless of how many vehicles are in it.
Why does route distance not change column length?
Column length is computed only from vehicle count, vehicle length, and vehicle spacing (line 9) -- route distance is a separate figure used later to compute travel time (line 26). A longer route takes longer to drive, but it does not stretch or compress the physical length of the column itself.
How much do planned halts add to total time?
Total time adds travel time to total halt time, which is planned halts multiplied by halt duration in minutes, converted to hours (lines 27-28). Two 15-minute halts add 30 minutes on top of travel time regardless of road condition or convoy speed, since halt time is computed independently of the movement formula.
What is the difference between pass time and closure time?
Pass time is how long it takes the entire column to move past a single fixed point, computed from column length divided by convoy speed (line 31). Closure time adds that pass time to travel time (line 34), estimating the gap between when the lead vehicle departs and when the last vehicle arrives -- useful for scheduling a route as clear before the next convoy can use it.
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