Transportation Engineering
Roadway Capacity Analysis Tool
Roadway Characteristics
Enter the roadway characteristics to calculate capacity and level of service based on Highway Capacity Manual (HCM) methodology.
Capacity Analysis Results
Base Capacity
2,400
passenger cars/h/lane
Adjusted Capacity
2,150
passenger cars/h/lane
Volume-to-Capacity Ratio
0.85
v/c ratio
Level of Service
D
LOS
Roadway Visualization
Capacity Adjustment Factors
| Factor | Value | Adjustment | Description |
|---|
Level of Service Criteria
Analysis Methodology
This calculator uses Highway Capacity Manual (HCM) methodologies to determine roadway capacity and level of service:
- Base Capacity: Maximum throughput under ideal conditions (typically 2,400 pcphpl for freeways)
- Adjustment Factors: Factors that reduce capacity based on real-world conditions
- Level of Service (LOS): Qualitative measure from A (best) to F (worst) based on density and v/c ratio
Key adjustment factors include:
- Heavy Vehicles: Trucks and buses have lower performance characteristics
- Lane Width: Narrower lanes reduce capacity and increase crash risk
- Interchange Density: More interchanges increase weaving and reduce capacity
- Terrain: Rolling or mountainous terrain reduces heavy vehicle performance
| Level of Service | Density (pc/mi/ln) | Speed (mph) | v/c Ratio | Description |
|---|---|---|---|---|
| A | ≤ 11 | ≥ 60 | ≤ 0.35 | Free flow |
| B | 12-18 | 55-60 | 0.35-0.54 | Reasonably free flow |
| C | 19-26 | 50-55 | 0.55-0.74 | Stable flow |
| D | 27-35 | 45-50 | 0.75-0.84 | Approaching unstable flow |
| E | 36-45 | 30-45 | 0.85-1.00 | Unstable flow |
| F | > 45 | < 30 | Varies | Forced flow |
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