# AADT Calculation

How do you calculate Average Annual Daily Traffic (aadt)?

## How to Calculate Average Annual Daily Traffic?

AADT is the abbreviation of Annual average daily traffic. It is the average vehicle traffic of one year on a highway. AADT is calculated by dividing the total volume of vehicle traffic on a highway for a year by 365 days. AADT is measured to determine the funding for maintenance and improvement of the roads.

Here is a brief tutorial on how to calculate AADT using the simple steps, knowing the total volume of daily traffic for the year.

**Formula:**

**AADT = (Total volume of vehicle traffic for 1 year) / 365 days**

**Measuring AADT and types of Daily Traffic:**

There are two techniques used to measure AADT, one is Continuous count data collection method and the other is Short-term data collection method, also known as Coverage count data collection method.

→ Using Continuous count data collection method, sensors are permanently embedded into a road and traffic data is measured all 365 days.

→ Using Short-term data collection method, traffic is collected with portable sensors that are placed on the roads and traffic data is recorded for 2 to 14 days.

The traffic data collection sensors are devices which use radar, laser, or sonar technologies.

The Annual Average Daily Traffic (AADT) is measured every three years for the same road.

**There are different types of measurements related to Daily Traffic, which are as follows:**

→ Annual Average Weekday Traffic (AAWT) - Includes only Monday to Friday Data. Public holidays are excluded.

→ Average summer daily traffic (ASDT) - Data is collected during summer only.

→ Average Daily Traffic (ADT) - The average number of vehicles passing both to and fro, at a particular point of the road in a 24-hour period. Data collected for a year and divided by 365 days.

Lets consider an example,

What will be the AADT (Annual Average Daily Traffic) for a highway of 800 kms, provided the traffic data collected by the sensors say the total volume number of vehicles passing to and fro in a year on the highway is 4380546.

**AADT Step by Step Calculation**

**Step 1: **Assigning the given values

Total Volume of Vehicle Traffic for 1 year = 4380546

**Step 2:** Substituting the values in the formula,

Annual Average Daily Traffic (AADT)

= (Total volume of vehicle traffic for 1 year) / 365 days

= 4380546/365

= 12001.4 Vehicles / day

Hence Annual Average Daily Traffic (AADT) for that particular highway is **12001.4** vehicles per day.

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