PE STUDY

Traffic Volume

The number of vehicles that pass a specific point on a roadway during a given time period, typically measured in vehicles per hour.

Traffic Flow Rate

The rate at which vehicles pass a specific point on a roadway, usually expressed in vehicles per hour.

Traffic Speed

The average speed of vehicles traveling on a roadway, often measured in miles per hour (mph) or kilometers per hour (km/h).

Traffic Density

The number of vehicles occupying a given length of roadway at a specific time, typically measured in vehicles per mile or vehicles per kilometer.

Time Mean Speed (TMS)

The average speed of vehicles over a specific segment of roadway, calculated by dividing the total distance traveled by the total time taken. It is often used in traffic studies to assess overall traffic performance.

Space Mean Speed (SMS)

The average speed of all vehicles on a given stretch of roadway, calculated by taking the total distance traveled divided by the total time for all vehicles, accounting for variations in individual speeds.

Traffic Headway

The time interval between two vehicles as they pass a specific point on the roadway, usually measured in seconds. It is an important metric for analyzing traffic flow and capacity.

Traffic Gap

The time interval between the passing of two successive vehicles in the same lane, indicating the space available for a vehicle to merge or change lanes. It is crucial for assessing the safety and efficiency of traffic movements.

Traffic Capacity

The maximum number of vehicles that can pass a given point on a roadway in a specified time period under prevailing conditions. It is a critical factor for roadway design and traffic management.

Level of Service (LOS)

A measure used to evaluate the operational conditions of a traffic facility, considering factors such as speed, travel time, congestion, and freedom to maneuver. LOS is typically categorized from A (best) to F (worst) to assess the quality of service provided to drivers.

Peak Hour Factor (PHF)

A measure of traffic fluctuation within one hour. Always between (0.25-1.0) with 1.0 = good and 0.7 = congestion.