Annual average daily traffic

Annual average daily traffic, abbreviated AADT, is a measure used primarily in transportation planning, transportation engineering and retail location selection. Traditionally, it is the total volume of vehicle traffic of a highway or road for a year divided by 365 days. AADT is a simple, but useful, measurement of how busy the road is. Newer advances from GPS traffic data providers are now providing AADT counts by side of the road, by day of week and by time of day.


Highway 401 east of Highway 400
Highway 401 in Ontario, Canada, has an AADT of over 400,000 in some sections of Toronto.[1]

One of the most important uses of AADT is for determining funding for the maintenance and improvement of highways.

In the United States the amount of federal funding a state will receive is related to the total traffic measured across its highway network. Each year on June 15, every state in the United States submits a Highway Performance Monitoring System HPMS report. The HPMS report contains various information regarding the road segments in the state based on a sample (not all of the road segments) of the road segments. In the report, the AADT is converted to vehicle miles traveled (VMT). VMT is the AADT multiplied by the length of the road segment. To determine the amount of traffic a state has, the AADT cannot be summed for all road segments since an AADT is a rate. The VMT is summed and is used as an indicator of the amount of traffic a state has. For federal-funding, formulas are applied to include the VMT and other highway statistics.

In the United Kingdom AADT is one of a number of measures of traffic used by local highway authorities, Highways England and the Department for Transport to forecast maintenance needs and expenditure.

Data collection

Traffic Counter on BIA Road J-9
A traffic counter on BIA Road J-9 in the United States

To measure AADT on individual road segments, traffic data is collected by an automated traffic counter, hiring an observer to record traffic or licensing estimated counts from GPS data providers. There are two different techniques of measuring the AADTs for road segments with automated traffic counters. One technique is called continuous count data collection method. This method includes sensors that are permanently embedded into a road and traffic data is measured for the entire 365 days. The AADT is the sum of the total traffic for the entire year divided by 365 days. There can be problems with calculating the AADT with this method. For example, if the continuous count equipment is not operating for the full 365 days due to maintenance or repair. Because of this issue, seasonal or day-of-week biases might skew the calculated AADT. In 1992, AASHTO released the AASHTO Guidelines for Traffic Data Programs,[2] which identified a way to produce an AADT without seasonal or day-of-week biases by creating an "average of averages." For every month and day-of-week, a Monthly Average Day of Week (MADW) is calculated (84 per year). Each day-of-week's MADW is then calculated across months to calculate an Annual Average Day of Week (AADW) (7 per year). Finally, the AADWs are averaged to calculate an AADT. The United States Federal Highway Administration (FHWA) has adopted this method as the preferred method in the [FHWA Traffic Monitoring Guide][1].

While providing the most accurate AADT, installing and maintaining continuous count stations method is costly. Most public agencies are only able to monitor a very small percentage of the roadway using this method. Most AADTs are generated using short-term data collection methods sometimes known as the coverage count data collection method. Traffic is collected with portable sensors that are attached to the road and record traffic data typically for 2 – 14 days. These are typically pneumatic road tubes although other more expensive technology such as radar, laser, or sonar exist. After recording the traffic data, the traffic counts on the same road segment are taken again in another three years. FHWA Traffic Monitoring Guide [2] recommends performing a short count on a road segment at a minimum of every three years. There are many methods used to calculate an AADT from a short-term count, but most methods attempt to remove seasonal and day-of-week biases during the collection period by applying factors created from associated continuous counters. Short counts are taken either by state agencies, local government, or contractors.

For the years when a traffic count is not recorded, the AADT is often estimated by applying a factor called the Growth Factor. Growth Factors are statistically determined from historical data of the road segment. If there is no historical data, Growth Factors from similar road segments are used.

Annual Average Weekday Traffic (AAWT)

Annual average weekday traffic (AAWT) is similar to AADT but only includes Monday to Friday data. Public holidays are often excluded from the AAWT calculation.

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.[3]

Average Daily Traffic

Average daily traffic or ADT, and sometimes also mean daily traffic, is the average number of vehicles two-way passing a specific point in a 24-hour period, normally measured throughout a year. ADT is not as highly referred to as the engineering standard of AADT which is the standard measurement for vehicle traffic load on a section of road, and the basis for most decisions regarding transport planning, or to the environmental hazards of pollution related to road transport.[4][5]


  1. ^ Ontario Ministry of Transportation. Traffic Volumes. 2010. Accessed 2015-12-09.
  2. ^ AASHTO Guidelines for Traffic Data Programs. American Association of State Highway and Transportation Officials. 1992.
  3. ^ "Traffic counting on the roadways of Croatia in 2009 - digest" (PDF). Hrvatske ceste. May 1, 2010. Archived from the original (PDF) on July 21, 2011.
  4. ^ Gauderman, W James; et al. (2005). "Childhood Asthma and Exposure to Traffic and Nitrogen Dioxide".
  5. ^ Gary A. Davis (2007). "Accuracy of Estimates of Mean Daily Traffic: A Review". Archived from the original on 2012-07-16.

The 1992 Edition of the AASHTO Guidelines is out of date. The current edition is from 2018. The Gary Davis article was published in Transportation Research Record 1593, 1997. the date currently shown in the article is the date of an on-line posting.

External links

Arasvika–Hennset Ferry

The Arasvika–Hennset Ferry is a ferry service on County Road 682 across Arasvik Fjord in the Nordmøre district in the Norwegian county of Møre og Romsdal. It connects the Arasvika ferry dock on the island of Ertvågsøya in the municipality of Aure to the Hennset ferry dock on the mainland in the municipality of Halsa. The route is operated by the transport conglomerate Fjord1.The duration of the passage is 15 minutes, and the 3.2-kilometer (2.0 mi) route is served by MF Driva with 22 departures per day in each direction every day. In 2014 the annual average daily traffic was 98 vehicles.

Davey Street, Hobart

Davey Street a major one way street passing through the outskirts of the Hobart Central business district in Tasmania, Australia. Davey street is named after Thomas Davey, the first Governor of Van Diemen's Land. The street forms a One-way couplet with nearby Macquarie Street connecting traffic from the Southern Outlet in the south with traffic from the Tasman Highway to the east and the Brooker Highway to the north of the city. With Annual average daily traffic of 37,200, the road is one of the busier streets in Hobart.

The Public Buildings in the street can be dated back to the 1840s It also was regularly photographed in the nineteenth century Davey Street is featured as a property in the Australian version of Monopoly.

Domain Highway

The Domain Highway is a highway in Tasmania, Australia. The highway acts as a link road connecting traffic between Hobart's two busiest highways; The Tasman Highway and the Brooker Highway while also bypassing the Hobart city centre. With recorded annual average daily traffic of 25,000, the single carriageway road is busier than some of Hobart's dual carriageway highways. Commencing at the Brooker Highway at Cornelian Bay and heading southeast between the banks of the Derwent River and the Domain and Botanical Gardens. The highway ends at the Tasman Highway, on the western approach of the Tasman Bridge.

K-104 (Kansas highway)

K-104 is a state highway in Saline County, Kansas. The route travels 2.3 miles (3.7 km) from a junction with Interstate 135/U.S. Route 81 (I-135/US-81), at I-135 exit 86, to a junction with K-4. It has an annual average daily traffic of between 1000 and 1300 and is paved with composite pavement. The highway is not a part of the National Highway System. The route was established around 1967, and has not been changed since.

K-140 (Kansas highway)

K-140 is a state highway in Ellsworth and Saline Counties in the U.S. state of Kansas. The highway travels 33.224 miles (53.469 km) through mostly rural land between the cities of Ellsworth and Salina. In addition to connecting Ellsworth and Salina, K-140 travels through the communities of Carneiro, Brookville, and Bavaria. The highway has junctions with Kansas state highways K-14, K-156, K-111, and K-141, as well as Interstate 135. The route was originally established as U.S. Route 40 and was redesignated K-140 after US-40 was made concurrent with Interstate 70. K-140 is not a part of the United States National Highway System, and the entire route is paved with composite pavement. The western part of the highway is less traveled than the eastern part, with annual average daily traffic between 590 and 940 west of Brookville and between 700 and 1200 east of Brookville.

K-143 (Kansas highway)

K-143 is a state highway in Saline County, Kansas. The route runs 4.658 miles (7.496 km) in a general north-south direction through lands mostly used for agriculture from an interchange at Interstate 70 (I-70) in northern Salina, Kansas to a junction with U.S. Route 81 (US-81). The southern part of the route is a four-lane divided highway while the rest is a two-lane highway. It has an annual average daily traffic (AADT) between 1,580 and 4,133 vehicles. The route is paved with three different pavement types, and is not a part of the National Highway System. It was first designated as US-81 Alternate in the early 1970s with the designation being changed to K-143 in the early 1980s.

K-1 (Kansas highway)

K-1 is a 13.363-mile (21.506 km) state highway in Comanche County in the U.S. state of Kansas. Its southern terminus is at the Oklahoma border south of Buttermilk, where it continues as Oklahoma State Highway 34. Its northern terminus is at U.S. Route 160 and U.S. Route 183 south of Coldwater. The highway is not a part of the United States National Highway System. The highway has annual average daily traffic values between 600 and 645, and the entire route of K-1 is paved with partial design bituminous pavement.

K-232 (Kansas highway)

K-232 is a 17.263-mile-long (27.782 km) north–south state highway in central Kansas connecting the towns of Wilson and Lucas. The highway was first established in 1962 and expanded over the following two years. K-232 is designated by the Kansas Department of Transportation as the Post Rock Scenic Byway. The scenic byway derives its name from the abundant Fencepost limestone, also known as the Post Rock, which early settlers used as fence posts and in other construction in place of wood. The route was designated as a scenic byway both for the natural beauty of the area and unique towns located each end of the highway. Annual average daily traffic on the highway ranges from 238 to 340, and the entire route is paved with partial design bituminous pavement.

K-284 (Kansas highway)

K-284 is a short east–west spur highway in northern Lincoln County, Kansas, connecting the town of Barnard to K-14 approximately ten miles (16 km) north of Lincoln. The highway runs for 5.618 miles (9.041 km) from K-14 to Barnard, at which point the road continues east as a county-maintained paved road toward Ada and Minneapolis. K-284 is paved with partial design bituminous pavement and has annual average daily traffic values between 70 and 120. The route is not a part of the United States National Highway System. K-284 was first established between 1973 and 1974.

K-360 (Kansas highway)

K-360 is a state highway in Cowley County the U.S. state of Kansas. It follows a route around the south and east sides of Winfield. The highway was established in 1997. It starts at US-77 south of Winfield and proceeds east and north for 3.469 miles (5.583 km), ending at US-160 east of Winfield. K-360 is not a part of the United States National Highway System. The highway has annual average daily traffic values ranging from 2235 to 1179.

K factor (traffic engineering)

In transportation engineering, the K factor is defined as the proportion of annual average daily traffic occurring in an hour.

This factor is used for designing and analyzing the flow of traffic on highways. K factors must be calculated at a continuous count station, usually an "automatic traffic recorder", for a year before being determined. Usually this number is the proportion of "annual average daily traffic" (AADT) occurring at the 30th-highest hour of traffic density from the year's-worth of data. This 30th-highest hour of traffic is also known as "K30" or the "Design Hour Factor". This factor improves traffic forecasting, which in turn improves the ability of designers and engineers to plan for efficiency and serve the needs of this particular set of traffic. Such forecasting includes the selection of pavement and inclusion of different geometric aspects of highway design, as well as the effects of lane closures and necessity of traffic lights. Engineers have reached consensus on identify K30 as reaching a reasonable peak of activity before high outliers of traffic volume are used as determinative of overall patterns.

The K factor has three general characteristics:

K generally decreases as AADT increases.

K generally decreases as development density increases.

K is generally highest near recreational facilities, next highest in rural and suburban areas, and lowest in urban areas.Another notable proportions of K is the measure of K100 (the proportion of AADT occurring during the 100th highest hour of the design year). This proportion is also known as the Planning Analysis Hour Factor.

Macquarie Street, Hobart

Macquarie Street a major one way street passing through the outskirts of the Hobart Central business district in Tasmania, Australia. Macquarie street is named after Lachlan Macquarie, who oversaw the planning of Hobart’s inner city grid layout. The street forms a One-way couplet with nearby Davey Street connecting traffic from the Southern Outlet in the south with traffic from the Tasman Highway to the east and the Brooker Highway to the north of the city. With annual average daily traffic of 28,500, the road is one of the busier streets in Hobart.

From the South Hobart intersection with Cascade Road, Washington Street and Darcy Street, Macquarie Street runs approximately 2 km (1.2 mi) east from the suburb of South Hobart as a two-way street until it reaches the intersection with the southern outlet where it becomes a one-way street for the duration of its length. It is primarily four lanes with the exception of its two-way section which is one lane both ways. The intersections on the one-way portion of the street are regulated by Synchronised traffic lights.

Macquarie Street borders the city garden Franklin Square. Prominent buildings in the street include the Hotel Grand Chancellor, the Lands Building, which houses the Department of Primary Industries, Water and Environment; the Mercury building; St Davids Cathedral; and the Reserve Bank Building.

Macquarie Street is featured as a property in the Australian version of Monopoly.

Ontario Highway 802

Tertiary Highway 802, commonly referred to as Highway 802, is a provincially maintained access road in the Canadian province of Ontario, located in Thunder Bay District.

Ontario Highway 805

Tertiary Highway 805, commonly referred to as Highway 805, is a provincially maintained access road, located within the Nipissing District. A northerly extension of Highway 539A, the road extends for approximately 40 kilometres (25 mi) to Obabika Lake, providing road access to the Chiniguchi Waterway, Obabika River and Sturgeon River provincial parks.

Quebec Autoroute 19

Autoroute 19, also known as Autoroute Papineau (Papineau Highway), is an autoroute in Quebec. It crosses the Rivière des Prairies via the Papineau-Leblanc Bridge, connecting the borough of Ahuntsic-Cartierville in Montreal and the Duvernay neighbourhood in Laval.

There are plans to widen Route 335 to four lanes, which would be a continuation of A-19 from Autoroute 440 to the Athanase David Bridge, on Rivière des Mille Îles, and Bois-des-Filion to relieve congestion along that stretch. The lands reserved for the project were expropriated in 1973 in conjunction of a future extension of the A-19. In 2007 Transport Minister Julie Boulet gave the green light for studies in the area.A super two highway exists in Bois-des-Filion, north of Route 344 and south of Autoroute 640, just north of Pont David, which runs on the Highway 19 right-of-way.

The city street Papineau Avenue in Montreal is signed as Autoroute 19, from Autoroute 40 northwards. It was once envisioned that A-19 would extend to the Jacques Cartier Bridge, and run below surface level south of the Metropolitan Expressway, like the Decarie Expressway. An autoroute-grade limited access expressway exists between the southern end of the Jacques Cartier Bridge and the northern end of the limited access expressway portion Route 116/Route 112 in St. Hubert, that is otherwise unsigned. The 112/116 expressway from the Jacques Cartier Bridge approach (the southern end of A-19) to Quebec Autoroute 30 was to have been designated Quebec Autoroute 16.

Quebec Autoroute 440 (Laval)

For Autoroute 440 in Quebec City, see Quebec Autoroute 440 (Quebec City).Autoroute 440 (or A-440, also known as Autoroute Jean-Noël-Lavoie and previously as Autoroute Laval) is a provincial highway that runs across the city of Laval, Quebec from Autoroute 13 to Autoroute 25. It is currently 18.2 km (11.3 mi) long, proceeding across Île Jésus on an east–west axis. It links every highway or expressway that connects Montreal to the North Shore.

Originally, it would have continued West in the Avenue des Bois corridor and crossed Rivière des Prairies on Bigras and Bizard Islands. On the latter island, the right-of-way is actually a public park. On the Island of Montreal, the A-440 right-of-way is just west of Boulevard Chateau-Pierrefonds. The autoroute would have ended at the Chemin Sainte-Marie interchange (Exit 49) on Autoroute 40.

Western terminus: Av. Des Bois (Ste-Dorothée neighbourhood) (km 16)

Eastern terminus: Autoroute 25 (St-Vincent-De-Paul neighbourhood) (km 34)

Lowest Annual Average Daily Traffic: 13 500 vpd (between R-117 and Avenue des Bois) (2000)

Highest Annual Average Daily Traffic: 131 000 vpd (between Des Laurentides blvd. and Industriel blvd.) (2000)

Rocky Hill–Glastonbury ferry

The Rocky Hill–Glastonbury ferry is a seasonal ferry crossing the Connecticut River between the towns of Glastonbury and Rocky Hill, Connecticut and is part of Route 160. It is believed to be the oldest continuously operated ferry service in the United States. The river crossing has an annual average daily traffic of 400.

South Arm Highway

The South Arm Highway (part of the B33 road route) is a highway serving the southern suburbs of Hobart, on the eastern shore of the River Derwent in Tasmania, Australia. The highway is a major trunk road that carries heavy commuter traffic south from the Eastern Outlet to Howrah and Rokeby.

As one of the Tasman Highway's principle Feeders and one of the eastern shore's major transport corridors, The South Arm Highway facilitates the movement of traffic between the suburbs and satellite communities to the south with the city centre and ultimately, other major cross city highways. With annual average daily traffic (AADT) of 17,000, the highway is considered a major traffic corridor within Hobart. The designation "South Arm Highway" arises from its journey south (via Rokeby Road) to South Arm.

Traffic count

A traffic count is a count of vehicular or pedestrian traffic, which is conducted along a particular road, path, or intersection. A traffic count is commonly undertaken either automatically (with the installation of a temporary or permanent electronic traffic recording device), or manually by observers who visually count and record traffic on a hand-held electronic device or tally sheet. Traffic counts can be used by local councils to identify which routes are used most, and to either improve that road or provide an alternative if there is an excessive amount of traffic. Also, some geography fieldwork involves a traffic count. Traffic counts provide the source data used to calculate the Annual Average Daily Traffic (AADT), which is the common indicator used to represent traffic volume. Traffic counts are useful for comparing two or more roads, and can also be used alongside other methods to find out where the central business district (CBD) of a settlement is located. Traffic counts that include speeds are used in speed limit enforcement efforts, highlighting peak speeding periods to optimise speed camera use and educational efforts.

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