Calculator Inputs
Use manual RTT or build RTT from detailed traffic assumptions.
Plotly Graph
The chart compares handling capacity against elevator count using your current assumptions.
Example Data Table
| Scenario | Population | Cars | Rated Load | Load Factor | RTT | Handling Persons / 5 min | Handling % | Interval |
|---|---|---|---|---|---|---|---|---|
| Office Mid-Rise | 1,200 | 4 | 1,000 kg | 80% | 110 sec | 113.45 | 9.45% | 27.50 sec |
| Retail Block | 900 | 3 | 1,000 kg | 75% | 95 sec | 92.37 | 10.26% | 31.67 sec |
| Residential Tower | 600 | 2 | 800 kg | 85% | 85 sec | 60.00 | 10.00% | 42.50 sec |
Formula Used
Rated persons = floor(rated load kg ÷ average person weight)
Effective car load = rated persons × loading factor
RTT detailed = terminal time + lobby time + [2 × highest reversal floor × travel time per floor] + [average stops × (door cycle time + transfer time per stop)]
Group handling persons = (period seconds × effective car load × elevators) ÷ RTT
Handling capacity % = (group handling persons ÷ population served) × 100
Interval = RTT ÷ number of elevators
Required elevators = ceiling[(target passengers × RTT) ÷ (period seconds × effective car load)]
These equations are useful for early traffic studies and concept design checks.
How to Use This Calculator
- Enter the population served during the traffic peak.
- Set the target handling percentage for the chosen building type.
- Enter car load, average person weight, loading factor, and elevator count.
- Choose manual RTT if you already know round trip time.
- Choose detailed RTT to build travel and stop assumptions.
- Submit the form and review handling percentage, interval, and required cars.
- Use the CSV or PDF buttons to save your study output.
- Review the Plotly graph to see how extra cars change performance.
Frequently Asked Questions
1. What is elevator handling capacity?
It is the number of passengers a lift group can move during a set peak period, usually five minutes. Designers compare that value with total building population.
2. Why does interval matter?
Interval estimates how often a car arrives at the main landing. Shorter intervals usually mean lower waiting time and better passenger comfort during peak demand.
3. Why is effective car load lower than rated capacity?
Cars rarely leave the lobby at absolute rated capacity every trip. Loading factor accounts for imperfect filling, passenger behavior, and operational variability.
4. When should I use manual RTT?
Use manual RTT when a supplier study, simulation, or prior design already gives a reliable round trip time. It speeds up comparison between options.
5. When should I use detailed RTT build-up?
Use the detailed mode during early planning, when you know travel assumptions, stops, and door times but do not yet have a completed traffic simulation.
6. Is a five-minute period always required?
Five minutes is common for up-peak checks, but some projects use different periods. This calculator lets you change the period to match your brief.
7. Can this calculator replace full traffic analysis software?
No. It is best for planning studies, option screening, and quick design reviews. Final sizing should consider zoning, dispatch logic, and real passenger distributions.
8. What target handling percentage should I choose?
That depends on building use, service quality goals, and local standards. Offices often need higher targets than residential buildings because peak arrival demand is sharper.