Administrative process simulation · discrete-event, Prosimos

AW-10 · Purchase Requests: Requisition, Sourcing, Receipt and Payment Follow-up: what the process does under load

The process model beside the controlled document (AW-10.process.yaml) states one performer per step, the decision branches and their loops, a duration per step, the resource pool and its calendar. A scenario is a named change to that model. Each row below is the same process with one thing changed.

Read the numbers as a shape, not a forecast. Every duration in this model is a service-standard target (AW-10 v0.2 service standards and IOL-OPS-002 v0.1 indicators, 2026-09-18). The arrival rate is an estimate. Nothing on this page is measured; the first calibration replaces the arrival rate with last year's count of cases and the durations with event timestamps from the platform. Results are the mean of 5 runs of 400 cases each.

Scenarios

Scenario	Cycle time, mean days	Median	90th percentile	Waiting, days per case	Work, hours per case	Cases reaching the last step	Busiest role, utilisation
baseline Baseline: the model as stated in the document	183	213	293	147	54.1	85%	SDO Procurement Officer 88%
first-pass-95 First-pass acceptance raised from 85% to 95% by a form with mandatory fields	189	223	298	151	54.1	87%	SDO Procurement Officer 88%
no-blackout Purchasing window removed: requests raised when the need arises	213	256	325	176	54.4	85%	SDO Procurement Officer 90%
second-procurement-officer A second SDO Procurement Officer	40.4	39.3	69.4	3.2	54.5	86%	SDO Procurement Officer 56%

Cycle time counts calendar days from the trigger to the case's end, including cases closed early (declined, rejected, never resubmitted), which is why the mean can sit below the median. Waiting is time a case spends queued for a person; work is the time people spend on it.

Baseline: who is busy

Role	Headcount in the model	Utilisation
SDO Procurement Officer	1	88%
HQ Contracting and Procurement	4	13%
Requester	40	4%
Dean	1	3%
SDO Head of Finance	1	3%
HAO	1	3%
Department Chair	6	2%
HQ Finance	4	0%

Baseline: where a case waits

Step	Times performed per run	Average wait before the step, days	Average work, hours
1. Identify the need and check existing provision	400	0.3	4.0
2. Prepare the request and specification	554	0.0	6.0
3. Endorse the request	554	0.0	1.0
4. Completeness and budget review	438	28.5	2.0
6. Approve within delegation	373	0.0	1.0
7. Raise the requisition in GRP	338	30.6	1.6
8. Determine the sourcing route and source	363	0.0	5.9
9. Evaluate offers and award	363	0.6	5.9
10. Coordinate delivery and receive	354	32.5	2.9
5. Return the request for correction	90	32.3	0.5
10 working days	20	0.0	0.0
11. Record receipt, register the asset and record any in-kind valuation	338	32.2	1.4
12. Follow up payment and close	338	30.5	2.0

Files

Simulation model: AW-10.bpmn (plain BPMN 2.0 for the simulator). Executable model: exec/AW-10.bpmn (BPMN 2.0, isExecutable, FEEL conditions, potential owners). Scenario parameter files (Prosimos):

Re-run: python3 Site/run_simulations.py AW-10 after pip install prosimos pyyaml. Results are committed as data under Simulator/process/results/ because the site build does not install the simulator.