Safely Implementing Rolling Roadblocks for Short-Term Road Work

Long Description for Slide 35

Definitions

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.
DENSITYA	Free Flow Density in vehicles per mile. the traffic density under free flow conditions.
DENSITYB	Forced Flow Density in vehicles per mile. The traffic density under forced flow conditions.
DENSITYC	Congested Flow Density in vehicles per mile. The traffic density under congested flow conditions.
FHV	Heavy-vehicle adjustment factor. This factor is used to convert hourly traffic to equivalent passenger cars. Heavy vehicles include trucks, busses and recreational vehicles.
FLOWA	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.
FLOWB	Forced Traffic Flow Rate in passenger cars per hour per lane. this is the traffic flow rate within the queue.
FLOWC	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.
Pt	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.
Qmax	The maximum queue length. The maximum queue length occurs when the pacing vehicles reach the work zone.
SC	The average speed of passenger cars when the roadway reaches capacity.
SP	Pacing Speed in MPH. This is the speed that the pacing vehicles travel.
Sr	Regulatory Speed in MPH. This is the posted speed on the roadway segment.
SWA	Speed of Shockwave 'A' in MPH. The speed of the shockwave at the boundary between traffic 'FLOWA' and traffic 'FLOWB'.
SWB	Speed of Shockwave 'B' in MPH. The speed of the shockwave at the boundary between traffic 'FLOWA' and traffic 'FLOWc'.
TD	Time to dissipate the queue in minutes. TD is the amount of time beginning at the point when the pacing vehicles leave the roadway until the traffic returns to normal operating conditions.
Ttotal	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.
tw	Work Duration in minutes. This is the work time allotted for overhead construction.