Simulating vehicle flows before building an ICD: what 5 questions must a Digital Twin answer?

A site layout drawing shows where facilities are located. It does not show how 40 trucks arriving in one hour will queue, whether the weighbridge becomes a bottleneck, or how long an RTG stopped for maintenance will slow the yard. Discrete-event simulation and Digital Twin turn those questions into scenarios that can be measured before construction.

BIM, simulation and Digital Twin are not the same thing

BIM organizes the geometric information and attributes of a facility. Simulation uses rules, time distributions and resources to test system behavior. A Digital Twin connects the model to operational data to update status and support decisions over time. A project can start with BIM and design simulation, then upgrade to a Digital Twin once the operating system has sufficiently reliable data.

1. How long will the queue be at the gate?

The model needs inputs for each time window: truck arrivals, rate of documents with errors, identification time, weighing, inspection and barrier opening. Outputs are not just trucks per hour but also queue length, median waiting time and worst-case waiting time in the peak scenario.

2. How much equipment is enough?

Adding a reach stacker or RTG will not necessarily raise productivity if the bottleneck is at the gate or the pick-up/delivery area. The simulation must follow containers through each stage, measuring equipment utilization, empty travel time, waiting time and number of rehandling moves. This lets the project owner compare equipment configurations on the same cargo flow.

3. Where do truck, people and equipment flows conflict?

Intersections, reversing points, waiting areas and warehouse doors should be checked over time, not just by distance on the drawings. The model should record the number of crossings, junction occupancy time and the impact of a truck stopping in the wrong position. This is the data for adjusting one-way flow, gate location or buffer zones.

4. What failures can the system withstand?

Scenarios should include the loss of a gate lane, equipment breakdown, heavy rain, temporary closure of a yard area, delayed TOS data or trucks bunching up after restricted hours. The goal is not to predict every incident precisely, but to find where the system breaks down fastest and prepare a contingency operating plan.

5. How can phase two be added without disrupting phase one?

Phased simulation helps test when yards, gates or equipment need to be added. It also shows which infrastructure should be fully built from the start, such as roads, drainage, substations and data lines, and which items can be added as volumes grow.

Minimum data set for the model

Required: time series of truck arrivals, container mix, service time at each stage, dwell time, flow diagrams, equipment productivity and schedules, shifts, priority rules and incident data. Where real data is not yet available, range-based assumptions can be used, but the source must be stated clearly and a sensitivity analysis run.

Indicators to put on the dashboard

Truck turnaround time, queue length, equipment utilization, number of rehandling moves, throughput, container dwell time and number of conflicts at intersections are the core indicators. Every layout change must be assessed against the same set of indicators, to avoid choosing an option merely because it looks good in visuals.

Start small but build the right data architecture

There is no need to wait for a complete Digital Twin before it delivers value. A project can simulate the gate and yard separately at the design stage, then connect weighbridge, OCR, TOS and equipment data once in operation. What matters is to agree object codes and indicators from the start so the model does not become a demo file detached from operations.

Reference sources

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