A

Arterial

A major thoroughfare.

Automated Vehicle Identification (AVI)

system or Automatic Vehicle Monitoring System or Automatic Vehicle Location System. A system in which electronic equipment on a vehicle sends signals back to a central control facility, locating the vehicle and providing other information about its operations or about its mechanical condition. AVI is also referred to as Automatic Vehicle Monitoring System and Automatic Vehicle Location System.

Average Annual Daily Traffic (AADT)

The total traffic for a year divided by 365.

Average Daily Traffic

is defined as the total traffic volume during a given period (from 1 to 364 days) divided by the number of days in that period. Current ADT volumes can be determined by continuous traffic counts or periodic counts. Where only periodic traffic counts are taken, ADT volume can be established by applying correction factors such as for season or day of week. For roadways having traffic in two directions, the ADT includes traffic in both directions unless specified otherwise.

Average Weekday Daily Traffic (AWDT)

The total traffic for an average weekday. An average weekday is a representative weekday computed as the mathematical average of several typical weekdays selected at random throughout the year. A typical weekday has no anomaly such as heavy traffic due to a special public event or light traffic due to inclement weather. Average Saturday and Sunday data, including holiday service, are determined the same way.

B

Benefit/Cost (B/C) ratio

B/C is used to compare the benefit versus the cost of proposed alternatives. For highway projects, benefits may include reduced fuel consumption, travel time, and air pollution; costs may include construction, right of way, and maintenance.

Bottleneck

Highway sections that experience operational problems such as congestion. Bottlenecks may result from factors other than reduced roadway width. For example, the close spacing of exit and entrance ramps can cause weaving patterns that result in congestion. A less obvious example is a steep freeway grade that can slow trucks and cause a localized "bottleneck."

C

Capital Area Metropolitan Planning Organization (CAMPO) (formerly ATS)

CAMPO is the Metropolitan Planning Organization (MPO) for the Austin area.

Capacity

Capacity refers to a rate of vehicular or person flow that can be expected to traverse a point or uniform section of a lane or roadway during a specific period, which is most often a peak 15-minute period, and which is not the maximum volume that can be accommodated during an hour, under prevailing roadway, traffic, and control conditions. Capacity and Level of Service (LOS) are analyzed separately and are not simply related to each other; both must be fully considered to evaluate the overall operation of a facility. Capacity analysis may be used in the computation of Volume-to-Capacity (V/C) ratios. In some cases, the V/C ratio is used to define LOS.

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