Concrete truck spacing calculator

How the calculation works

A pour stays continuous when the next truck arrives just as the previous one finishes discharging. The time one load takes to discharge therefore sets the dispatch interval, and the number of trucks is how many of those intervals fit into one full truck cycle.

The calculator assumes trucks run at a steady pace and that the pump or paver works at a constant rate. It rounds the number of trucks up, because a fraction of a truck means the pump would wait.

• Loads = total volume ÷ load per truck (rounded up)
• Discharge time = load per truck ÷ placement rate × 60
• Dispatch interval = discharge time
• Truck cycle = round-trip time + discharge time
• Trucks needed = truck cycle ÷ dispatch interval (rounded up, never more than the number of loads)
• Pour duration = total volume ÷ placement rate

Worked example

A 120 m³ slab is placed by a pump at 40 m³ per hour with 8 m³ trucks. Each load discharges in 8 ÷ 40 × 60 = 12 minutes, so a truck must leave the plant every 12 minutes. With a 60-minute round trip, one truck cycle takes 72 minutes, so 72 ÷ 12 = 6 trucks keep the pump busy. The pour needs 15 loads and takes about 3 hours.

How to schedule concrete deliveries for a pour

1. 1

   Confirm volume, mix and placement rate

   Agree the total volume, the mix and the rate the pump, paver or crew can actually place. The placement rate, not the plant output, decides how fast trucks can be emptied.

2. 2

   Measure the real round trip

   Use loading time, the travel time at the hour of the pour, washout and return. Morning traffic can add a lot to a trip that takes 30 minutes at midday.

3. 3

   Set the dispatch interval and truck count

   Use the calculator above, then add a spare truck for long pours or uncertain traffic so one late arrival does not stop the pump.

4. 4

   Book the plant slot and the trucks

   Reserve the trucks for the whole pour window and stagger the first loads so the pump does not wait at the start.

5. 5

   Track the pour as it happens

   Watch where each truck is and how long it waits on site. If trucks start queueing, stretch the interval; if the pump waits, add a truck.

Questions about truck spacing

How many trucks do I need for a concrete pour?

Divide the truck cycle time (round trip plus discharge) by the time one load takes to discharge, and round up. For a pump placing 40 m³ an hour with 8 m³ trucks and a 60-minute round trip, that is 72 ÷ 12 = 6 trucks.

How far apart should concrete trucks be spaced?

Send trucks at the interval it takes one load to discharge: load size divided by placement rate. An 8 m³ load at 40 m³ an hour discharges in 12 minutes, so trucks should leave the plant 12 minutes apart.

What should the round-trip time include?

Loading at the plant, travel to the site, the return trip and washout. Leave out the time spent discharging on site, because the calculator adds it from the load size and the placement rate.

Why does the calculator round the number of trucks up?

A fraction of a truck means there is a gap in deliveries and the pump or paver waits. Rounding up keeps the pour continuous; for long pours many dispatchers also add a spare truck.

Does it work in cubic yards?

Yes. Switch the units to yd³ and enter the volume, the load per truck and the placement rate in cubic yards. The formulas are the same in both units.