ATC |
Actual Traffic Counts. Hourly traffic volumes for a 24 hour period are needed. |

C |
Capacity. The capacity of the roadway under free flow conditions in passenger cars per hour per lane. |

DENSITY_{A} |
Free Flow Density in vehicles per mile. the traffic density under free flow conditions. |

DENSITY_{B} |
Forced Flow Density in vehicles per mile. The traffic density under forced flow conditions. |

DENSITY_{C} |
Congested Flow Density in vehicles per mile. The traffic density under congested flow conditions. |

F_{HV} |
Heavy-vehicle adjustment factor. This factor is used to convert hourly traffic to equivalent passenger cars. Heavy vehicles include trucks, busses and recreational vehicles. |

FLOW_{A} |
Traffic Demand Flow Rate in passenger cars per hour per lane. This is the traffic flow rate approaching the pacing operation from the upstream direction. |

FLOW_{B} |
Forced Traffic Flow Rate in passenger cars per hour per lane. this is the traffic flow rate within the queue. |

FLOW_{C} |
Congested Traffic Flow Rate in passenger cars per hour per lane. this is the traffic flow rate of the vehicles escaping the queue. |

HTD |
Hourly Traffic Demand in vehicles/hour. |

L |
Total Pacing Distance in miles. This is the total distance that the pacing vehicles are traveling at the pacing speed. It includes the distance required to clear traffic past the work area, and the distance required to provide the work duration. this distance is measured upstream from the work area. |

N |
Number of Lanes |

PSCF |
Peak Season Conversion Factor. |

P_{t} |
Percent Trucks (%). |

QDR |
Queue Dissipation Rate in MPH. The rate that the queue dissipates after the pace cars exit the roadway. |

QGR |
Queue Growth Rate in MPH. The rate that the queue grows from the time the pacing operation begins until the pace cars exit the roadway. |

Q_{max} |
The maximum queue length. The maximum queue length occurs when the pacing vehicles reach the work zone. |

S_{C} |
The average speed of passenger cars when the roadway reaches capacity. |

S_{P} |
Pacing Speed in MPH. This is the speed that the pacing vehicles travel. |

S_{r} |
Regulatory Speed in MPH. This is the posted speed on the roadway segment. |

SW_{A} |
Speed of Shockwave 'A' in MPH. The speed of the shockwave at the boundary between traffic 'FLOW_{A}' and traffic 'FLOW_{B}'. |

SW_{B} |
Speed of Shockwave 'B' in MPH. The speed of the shockwave at the boundary between traffic 'FLOW_{A}' and traffic 'FLOW_{c}'. |

T_{D} |
Time to dissipate the queue in minutes. T_{D} is the amount of time beginning at the point when the pacing vehicles leave the roadway until the traffic returns to normal operating conditions. |

T_{total} |
Total time to conduct the pacing operation. The time from when the pace cars enter the roadway until the queue has dissipated and normal traffic flow is restored. |

t_{w} |
Work Duration in minutes. This is the work time allotted for overhead construction. |