# Annual average daily traffic: Wikis

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# Encyclopedia

Annual average daily traffic, abbreviated AADT, is a measure used primarily in transportation planning and transportation engineering. It is the total volume of vehicle traffic of a highway or road for a year divided by 365 days. AADT is a useful and simple measurement of how busy the road is. It is also sometimes reported as "average annual daily traffic".

## Data collection

To measure AADT on individual road segments, traffic data is collected either by an automated traffic counter or hiring an observer to record traffic. There are two different techniques of measuring the AADTs for road segments. One technique is called continuous count data collection method. This is where sensors are permanently embedded into a road and traffic data is measured all 365 days. The AADT would be the sum of the total traffic for the entire year divided by 365 days. There is a problem with calculating the AADT with this method. The continuous count equipment is not operating for the full 365 days due to being shut down for maintenance or repair. A better calculation method is to average the daily traffic for each of the 12 months - MADT Monthly Average Daily Traffic - and take the average of the MADTs. This method is outlined in the [FHWA Traffic Monitoring Guide][1]. The continuous count method is costly. There are monthly maintenance fees involved and it is expensive to install and purchase the sensors. It can cost money to power the sensors if it is connected to the local power grid. It can cost money to maintain the communication connection whether it is a phone line or an IP address.

Annual average daily traffic, abbreviated AADT, is a measure used primarily in transportation planning and transportation engineering. It is the total volume of vehicle traffic of a highway or road for a year divided by 365 days. AADT is a useful and simple measurement of how busy the road is. It is also sometimes reported as "average annual daily traffic".

## Data collection

To measure AADT on individual road segments, traffic data is collected either by an automated traffic counter or hiring an observer to record traffic. There are two different techniques of measuring the AADTs for road segments. One technique is called continuous count data collection method. This is where sensors are permanently embedded into a road and traffic data is measured all 365 days. The AADT would be the sum of the total traffic for the entire year divided by 365 days. There is a problem with calculating the AADT with this method. The continuous count equipment is not operating for the full 365 days due to being shut down for maintenance or repair. A better calculation method is to average the daily traffic for each of the 12 months - MADT Monthly Average Daily Traffic - and take the average of the MADTs. This method is outlined in the [FHWA Traffic Monitoring Guide][1]. The continuous count method is costly. There are monthly maintenance fees involved and it is expensive to install and purchase the sensors. It can cost money to power the sensors if it is connected to the local power grid. It can cost money to maintain the communication connection whether it is a phone line or an IP address.

## Average summer daily traffic

Average summer daily traffic (abbreviated to ASDT) is a similar measure to the annual average daily traffic. Data collecting methods of the two are exactly the same, however the ASDT data is collected during summer only. The measure is useful in areas where there are significant seasonal traffic volumes carried by a given road.[1]