Traffic Count Frequently Asked Questions
A traffic count is a count of traffic on State Routes, major county roads, and major city streets. All traffic counts represent a typical 24 hour period, counting traffic in each direction of traffic flow.
Contact GDOT's Office of Transportation Data (OTD) by fax at (770) 986-1448 or by completing the OTD Inquiry Form or select "Georgia's State Traffic And Report Statistics (STARS)" or "Georgia ATR Traffic Data Reports" on the Transportation Statistics and Reports page.
Monday-Friday 8:00 AM - 4:45 PM (EST).
The most recent traffic counts are available for 2011. Select "Georgia's State Traffic And Report Statistics (STARS)" or "Georgia ATR Traffic Data Reports" on the Transportation Statistics and Reports page.
Normally, traffic counts are available by the spring of each year.
AADT stands for Annual Average Daily Traffic.
No, currently we do not provide traffic speed data.
The state of Georgia is required to collect a certain amount of traffic counts on the roadways throughout the state. The counts are compiled and reported in federal reports prepared each year. These reports help the federal government decide how much money the state of Georgia will get for transportation and road infrastructure projects each year.
Contact Georgia's Traffic Management Center (TMC) at (404) 624-1300, or visit Georgia NaviGAtor.
Contact Georgia's Office of Transportation Data by fax at (770) 986-1448 or by completing the OTD Inquiry Form.
One of the key variables in determining the VMT (Vehicle Miles Traveled) is the AADT (Annual Average Daily Traffic). The VMT is calculated by multiplying the AADT for a given road section times the length of the road section. This calculated value is the VMT for this road section.
To accumulate this figure by route or to summarize for reporting purposes, this number is accumulated for every road section.
For Example: You want to calculate the VMT for I-75. Since I-75 is a long route (355 miles) we know that it will have many road segments and AADT values to consider. For each road segment, the section length is multiplied by the applicable AADT for that segment and is accumulated. After this calculation has been performed on all of the road segments for I-75, the accumulated value is the VMT for I-75. In 2010, the Daily Vehicle Miles Traveled on I-75 was 14.2 million. This same calculation process is performed on all road segments for the State and is typically "rolled up" by functional classification road system, by county, by State, or any other jurisdiction or stratification that is available in our database.
Traffic counts are used to determine traffic patterns and flows for modeling purposes. They are also used in developing plans to aid in alleviating congestion with the construction of new routes or alternate designs.
For example, Georgia's Office of Materials Research uses a combination of truck percentages and Annual Average Daily Traffic (AADT) data to develop factors that assess the deterioration of pavement.
Georgia's Traffic Operations Office uses the volume data for safety related purposes (calculating crash rates and addressing safety issues).
The Federal Highway Administration (FHWA) requires every state to submit an annual Highway Performance Monitoring System (HPMS) report containing traffic count data, physical characteristics, and other pertinent road data. This submittal is used in legislation, and to determine State funding of highway and road projects.
Customers of the data include transportation planning professionals, educational institutions, design engineers, contractors, real estate agencies, private companies, and other government agencies. The data is used on national, state, and local levels for planning, modeling, allocation of funding, and informational purposes. Select "Designer's Manual - Georgia Highway System Administrative Review" on the Transportation Statistics and Reports page for general uses of traffic data.
There are two types of traffic counts, portable and permanent.
Portable traffic collection devices are placed on all types of road systems to collect traffic data during a typical 48 hour period. As of January 2011, there is an estimated 25,000 portable traffic count location sites in Georgia.
Permanent Automatic Traffic Recorder (ATR) sites count traffic seven days a week, 24 hours a day, 365 days a year. There is an estimated 354 permanent traffic count location sites.
Portable and permanent traffic counts are collected by our Road Data Collection Branch.
Roads are designated as State Routes (SR), County Roads (CR), and City Streets (CS), depending upon ownership.
The roads are divided into sections designated with Traffic Count (TC) numbers. Each TC number has an Average Annual Daily Traffic (AADT) count.
In order to ensure the most reasonable traffic data is reported in the long term, Georgia's Office of Transportation's portable traffic count program collects data on an annual cycle in which data is collected at each station for a 48-hour period Portable data is collected at locations that are distributed among the following stratification groups, known as Functional Classification Groups. Select "Highway System Status Map Series on the Maps page.
Permanent traffic data collection devices are used to continuously collect traffic data.
Portable traffic data collection devices are used to collect the traffic counts during typical travel conditions (not on holidays or weekends).
The raw hourly counts are adjusted by seasonal, daily, and axle factors to determine the Annual Average Daily Traffic (AADT).
Seasonal factors are developed according to 16 factor groups and calculated by dividing the average AADT by the monthly AADT for each location.
Daily factors are calculated by dividing the average AADT by the daily AADT. Factors are based on data provided by Automatic Traffic Recorders (ATR).
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