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Queueing network templates

Queueing Network — Emergency Department

Five-stage emergency pathway at 11 arrivals an hour, with a finite-capacity imaging suite and a senior-review loop back to assessment, solving to an 87% doctor utilisation and a 2.2-hour end-to-end stay.

Template previewQueueing network
Emergency department — Monday eveningOpen queueing network · 5 stations · 8 routes · arrivals 11/h · target ρ 85%0.940.060.420.5810.12 back0.8811/harrivals1exitTriageλ 11/h · ρ 73.3%Wq 6.3m · Lq 1.16W 14.3m · L 2.63G/G/2 · P(wait) 62.1%Doctor assessmentbottleneck×5λ 11.8/h · ρ 86.8%Wq 23.1m · Lq 4.55W 45.1m · L 8.89M/M/5 · P(wait) 69.2%Imagingλ 4.97/h · ρ 71.3%Wq 13.4m · Lq 1.11W 39.4m · L 3.24M/M/3/12 · blocked 0.8%Senior reviewλ 12.5/h · ρ 83%Wq 22.1m · Lq 4.6W 34.1m · L 7.09G/G/3 · P(wait) 69.7%Dischargeλ 11/h · ρ 54.8%Wq 1.9m · Lq 0.35W 10.9m · L 2M/M/3 · P(wait) 29.1%StationModelcK1/μλλ effaρP(wait)P(block)LqWqLWTriageG/G/22∞8m11/h11/h1.4773.3%62.1%0%1.166.3m2.6314.3mDoctor assessmentM/M/55∞22m11.8/h11.8/h4.3486.8%69.2%0%4.5523.1m8.8945.1mImagingM/M/3/1231226m4.97/h4.93/h2.1571.3%50.6%0.8%1.1113.4m3.2439.4mSenior reviewG/G/33∞12m12.5/h12.5/h2.4983%69.7%0%4.622.1m7.0934.1mDischargeM/M/33∞9m11/h11/h1.6454.8%29.1%0%0.351.9m210.9mBottleneck: Doctor assessment at ρ = 86.8% on 5 servers — 6 servers (1 more) would bring it under the 85% target.Offered 11/h · throughput 11/h · blocked 0.04/h (0.3%) · L 23.84 in system · W 2.17h end to end · 5 stationsStable — every station holds ρ below 1. Network response time is Little's law on the solved flows: W = L / throughput.

Make it your own.

title "Emergency department — Monday evening"
target 85%
arrivals Triage 11/h

# Triage is fast and predictable, so its service variability is BELOW
# exponential — cv 0.6 shortens the queue the M/M/c formula would predict.
station Triage              { servers: 2; service: 8m; cv: 0.6 }
station "Doctor assessment" { servers: 5; service: 22m }
station Imaging             { servers: 3; service: 26m; capacity: 12 }
station "Senior review"     { servers: 3; service: 12m; cv: 1.3 }
station Discharge           { servers: 3; service: 9m }

route Triage -> "Doctor assessment" 0.94
route Triage -> "Senior review" 0.06          # obvious admissions skip the SHO
route "Doctor assessment" -> Imaging 0.42
route "Doctor assessment" -> "Senior review" 0.58
route Imaging -> "Senior review" 1.0
route "Senior review" -> "Doctor assessment" 0.12   # sent back for more work-up
route "Senior review" -> Discharge 0.88
route Discharge -> exit 1.0