Not every project needs full simulation—but RTT alone can mislead when control is sophisticated or traffic is irregular. Here is how to pick the right method.
Round Trip Time (RTT) methods estimate how long a representative round journey takes under simplified assumptions. Monte Carlo and discrete-event simulation introduce randomness and queuing—often closer to real lobby behavior.
When RTT is enough
RTT remains the fastest approach for concept design: you fix passenger load, door times, floor heights and express a likely round trip duration. It is ideal when the client needs a budget option study across multiple car sizes and speeds.
When simulation adds value
- Mixed traffic patterns (hotel, hospital, mixed-use podium).
- Destination control or double-deck installations where analytical formulas struggle.
- Projects where contractual KPIs reference simulated AWT percentiles.
System type affects every method
Conventional collective control, destination dispatch and double-deck systems process hall calls differently. Applying one generic formula across all types understates or overstates performance. Liftaro applies system-aware adjustments so engineers see method results that reflect the selected control strategy.
Recommendation
Use RTT for screening alternatives, then validate shortlisted options with simulation before issuing a traffic report. Align the chosen method with what your client will accept at handover—and keep input data versioned as the architect updates floor plans.
