Roundabout Capacity Calculator
Poisson independent conflicting-arrival gap-acceptance entry capacity with caller calibrated critical/follow-up gaps, exact zero-flow limit; not HCM defaults or saturation guarantee. Caller independently establishes units, regime, calibration and applicability; this does not establish design-code compliance, authenticity, operational safety, treatment efficacy or a validated forecast.
Description
A gap-acceptance roundabout model relates conflicting flow to critical and follow-up gaps.
A gap-acceptance roundabout model relates conflicting flow to critical and follow-up gaps.1
Its capacity estimate depends on those supplied parameters rather than an installed traffic calibration. Use this tool to calculate roundabout Capacity from the supplied measurements and assumptions.
When to use Roundabout Capacity Calculator
Use this tool to calculate roundabout Capacity from the supplied measurements and assumptions. Establish the SI units or caller unit basis, load signs, measurement interval, model conditions and independently chosen coefficients or references.
How to use Roundabout Capacity Calculator and understand its results
- Establish the SI units or caller unit basis, load signs, measurement interval, model conditions and independently chosen coefficients or references.
- Enter observedConflictingFlowVehiclesSecond, callerMatchedCriticalGapSeconds, callerMatchedFollowUpSeconds, using the field meanings and rules below, then run the tool.
- Read gapAcceptanceRoundaboutCapacityVehiclesHour. Interpret the fields using their units, signs and evidence conventions below.
- If input validation fails, correct the reported field and run again. Before applying the result, check reference scope, model assumptions and any missing evidence or placeholder values.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| observedConflictingFlowVehiclesSecond | Observed conflicting flow vehicles second | number | Required |
| callerMatchedCriticalGapSeconds | Caller matched critical gap seconds | number | Required |
| callerMatchedFollowUpSeconds | Caller matched follow up seconds | number | Required |
Enter nonnegative conflicting flow in vehicles/s and positive critical and follow-up gaps in seconds. At zero conflicting flow use the limit 3600/followUp; otherwise use the exponential gap model, evaluating its denominator with expm1 for numerical resolution. Return vehicles/hour without estimating gaps or validating traffic applicability.
capacityVeh/h=3600×q×exp(−q×criticalGap)/(1−exp(−q×followUpGap)); q=0 limit=3600/followUpGap Use the exact units, boundary rules, ordering and missing-evidence conventions above.
| Output field | Meaning | Value type |
|---|---|---|
| gapAcceptanceRoundaboutCapacityVehiclesHour | Gap Acceptance Roundabout Capacity Vehicles Hour; follow the units, sign, ordering and evidence convention stated above | number |
{
"input": {
"observedConflictingFlowVehiclesSecond": 0.1,
"callerMatchedCriticalGapSeconds": 5,
"callerMatchedFollowUpSeconds": 2
},
"output": {
"gapAcceptanceRoundaboutCapacityVehiclesHour": 1204.5674663749357
}
}Limitations and assumptions
Its capacity estimate depends on those supplied parameters rather than an installed traffic calibration. Interpretation depends on the units, sampling scope and exact model described above.
All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse evidence arrays fail validation; the specific bounds and alignment requirements are stated above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful result reporting false, no matches or missing evidence.
Alternative or Complementary methods
Use Level of Service Delay Calculator for this related task: Delay classification compares observations with ordered inclusive upper edges.
Use Webster Signal Timing Calculator when its separate inputs and assumptions fit the question: Webster's cycle model relates lost time to independently established critical flow ratios.
References
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Roundabout Capacity Calculator — tool.io
Similar or alternative tools
- Level of Service Delay Calculator
Delay classification compares observations with ordered inclusive upper edges.
- Webster Signal Timing Calculator
Webster's cycle model relates lost time to independently established critical flow ratios.