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Calcimator

Level of Service (LOS) Calculator

Determine roadway Level of Service grade (A through F) from traffic volume, lane count, free-flow speed, and vehicle mix using HCM methodology.

Inputs

veh/hr
mph

Results

LOS Grade

A

DescriptionFree flow, minimal delay
Adjusted Flow Rate543 pc/hr/ln
Density9.1 pc/mi/ln
V/C Ratio0.23
Average Speed60 mph
Total Capacity4,800 veh/hr
How to Use This Calculator
  1. Enter Traffic Volume, Number of Lanes, and Free-Flow Speed.
  2. Set Peak Hour Factor, Heavy Vehicle %, and Terrain.
  3. Adjust Level, Rolling as needed.
  4. Review the LOS Grade result.
  5. Use Description and Adjusted Flow Rate (pc/hr/ln) to inform your decision.

What each input means

Traffic Volume
Total directional traffic volume in vehicles per hour for all lanes combined.
Number of Lanes
Number of lanes in one direction of travel.
Free-Flow Speed
Speed of traffic under low-volume conditions. Typically the posted speed limit plus 5-10 mph on freeways.
Peak Hour Factor
Ratio of hourly volume to peak 15-min flow rate. 0.92 is typical urban; 0.85 for rural.
Heavy Vehicle %
Percentage of trucks, buses, and RVs in the traffic stream.
Terrain
Terrain type affects passenger-car equivalency for heavy vehicles.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Traffic Volume = 1000, Number of Lanes = 2, Free-Flow Speed = 60, Peak Hour Factor = 0.92 = 6 input(s) provided
  2. Calculate LOS Grade
    A = A
  3. Calculate Description
    Free flow, minimal delay = Free flow, minimal delay
  4. Calculate Adjusted Flow Rate
    Adjusted Flow Rate
    543 = 543

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