Inputs
Use observed flows when possible. For work zones, consider peak and short-term surges.
Example Data
Sample inputs and typical outputs for a temporary two-way stop condition.
| Scenario | Minor vol (veh/h) | Conflicting vol (veh/h) | tc (s) | tf (s) | PHF | HV (%) | Delay (s/veh) | LOS |
|---|---|---|---|---|---|---|---|---|
| Daytime peak work zone | 300 | 900 | 6.5 | 3.5 | 0.90 | 8 | ~30–45 | D–E |
| Off-peak detour traffic | 180 | 650 | 6.0 | 3.4 | 0.95 | 5 | ~12–22 | B–C |
| Night shift with low demand | 80 | 350 | 6.0 | 3.2 | 0.98 | 4 | ~4–10 | A–B |
Formula Used
This tool uses a gap-acceptance capacity estimate plus a queueing delay approximation.
1) Adjusted flows (using PHF)
v' = v / PHF and vc' = vc / PHF
Lower PHF increases the short-term flow rate used for checking queues.
2) Minor-street capacity (planning estimate)
c = (3600 / tf) · e-(vc' · tc / 3600) · F
Where tc is critical gap (s), tf is follow-up time (s), and F bundles adjustments for heavy vehicles, grade, arrival pattern, and lanes.
3) Average stop delay (queueing approximation)
λ = v' / 3600, μ = c / 3600, Wq ≈ λ / (μ(μ − λ))
The reported stop delay adds startup and a small decel/accel allowance. If λ ≥ μ, the approach is flagged as oversaturated.
4) LOS (control delay thresholds)
A ≤ 10, B 10–15, C 15–25, D 25–35, E 35–50, F > 50 seconds per vehicle.
How to Use This Calculator
- Enter the minor-street volume and the conflicting major-street volume.
- Set critical gap and follow-up time based on field behavior or local defaults.
- Apply PHF to reflect short-term surges typical in work zones.
- Adjust for heavy vehicles, grade, and lane availability on the minor approach.
- Click Calculate Delay to view delay, queue, and LOS above the form.
- Use the download buttons to export a CSV summary or a PDF report.
Tip: If the tool reports oversaturation, consider temporary signal control, flagging, rerouting, added lanes, or staged closures.
Planning tool only. Validate with site geometry, local standards, and observed gap behavior.