The Atlanta area with its spider web structure.
There is virtually no grid network in Atlanta, and there is also little hierarchy in the underlying road network. The through roads are often not well developed, so that the majority of traffic is concentrated on the motorway network. Atlanta’s trunk road network has been called the least efficient in the United States, which has not grown along with suburbanization. Many important connections are still in the same condition as when they were still in rural areas.
Due to the large distances in the agglomeration and the spread of work and residential locations, the car is the only efficient means of transport. The road network is radial with a ring road. 8 highways radiate out from the center, with a number of smaller connections. Suburban highway connections are often lacking. Given the size of the conurbation, the highway network is not very large, but it does handle enormous amounts of traffic, making the highways in Atlanta particularly wide, up to 8 lanes in each direction, and quite massive in character. However, the layout of the motorway network does not match the traffic flows. Like public transport, the highway network is radial in character, while most movements are tangential, requiring many detour kilometers and seriously congesting the I-285 ring road. It is argued that the highway network was designed for the Atlanta of 1960, and not that of today. The secondary road network is not efficient enough to provide an alternative for traffic. The nodes are also large and complex, with many direct connecting curves, but lack of capacity is a problem at connections and nodes. There are no toll roads (anymore) in Atlanta, but there are HOT lanes.
In Atlanta, the highways are commonly referred to as freeways, unlike many surrounding states, where they are more commonly referred to as expressways. Atlanta is sometimes referred to as the ” Los Angeles of the South”.
According to jibin123, Atlanta has one ring road, the 100 kilometer long I-285. A ring around the urban area would have to be about 290 kilometers long, with suburbs still outside the ring.
|Road name||length||first opening||last opening||max AADT 2016|
|Interstate 20||97 km||1963||1966||215,000|
|Interstate 75||98 km||1952||1965||404,000|
|Interstate 85||135 km||1952||1965||404,000|
|The Perimeter||103 km||1963||1969||248,000|
|Interstate 575||50 km||1980||1985||102,000|
|Interstate 675||18 km||1987||1987||82,000|
|Interstate 985||39 km||1970||1970||68,000|
|Stone Mountain Freeway||16 km||1970||1970||117,000|
|Peachtree Industrial Boulevard||6 km||1996||1996||128,000|
|Langford Parkway||11 km||1960||1961||64,000|
|University Parkway||11 km||1971||1971||99,000|
|Georgia 400||60 km||1971||1993||209,000|
The highway plan of 1955.
Atlanta was a relatively small city in 1950, with a population of 330,000 and a small suburban area nearby. The plans for the highway network from that time envisaged a relatively small highway network with three through highways through the city and one ring road. These highways were mostly planned with 2×2 lanes, only around the center are 2×3 lanes planned from the start.
In 1952, Atlanta’s first freeway stretches, both part of the Downtown Connector, opened south of the city to the airport, and a short stretch north of downtown. In the next few years, most of the construction was done on the north side of downtown, namely the highway to the northeast (I-85) and northwest (I-75). After the Interstate Highway program was created in 1956, the construction of the highways went a lot faster. Interestingly, the Downtown Connector had a missing link in downtown for 12 years, it wasn’t until 1964 that this link opened with 2×3 lanes with a narrow grass median strip. The first highway to other parts of the country to be significantly completed from Atlanta was Interstate 85 to the northeast, which reached the South Carolina border as early as 1966.
The Interstate Highways were built within the ring in the 1960s. I-20 through Atlanta was completed in 1966, and the ring road was completed in 1969. Outside the ring road, there were still missing links until the 1970s. I-75 south of Atlanta was completed in 1972 and north of Atlanta in 1978. In 1979, I-85 southwest of Atlanta was completed and in 1979, I-20 west of Atlanta was completed, connecting the city to other cities in the southeastern United States.
Freeing the Freeways
What was not expected, however, was the gigantic population growth from the late 1960s. The urban area sometimes grew by 50,000 inhabitants per year, and the city became notorious for the enormous traffic jams from the late 1970s. During the 1980s, the “freeing the freeways” program was implemented, a $1.4 billion construction program designed to drastically improve highways. The Downtown Connector was then doubled from 2×3 to 2×6 lanes, I-85 was drastically widened from 2×2 to 2×5 to 2×6 lanes, as well as parts of I-75 and Interstate 285 as a ring road was then widened to 2×4 lanes. This program was completed in the early 1990s. For the 1996 Olympic Games in Atlanta, the road network was renovated again, albeit on a more limited scale. Thus, the Peachtree Industrial Boulevard (State Route 141) was converted to a freeway and I-285 on the north side of Atlanta was upgraded.
As in many American cities, Atlanta also saw Freeway Revolts in the 1970s, protests against the construction of new highways. These have partly been successful, because a number of important projects have also been canceled in Atlanta. For example, this was the extension of Interstate 675 as a north-south route through eastern Atlanta, between the Downtown Connector and I-285. An extension, State Route 400 was built in 1993 as a toll road in northern Atlanta. Another canceled plan was the Stone Mountain Freeway (US 78), which was to connect to the Downtown Connector from the eastern suburbs. Only the eastern suburbs have been built, as has the interchange with the Downtown Connector in the form of the Freedom Parkway. However, the missing link through eastern Atlanta has been called off. This project was also planned under the number I-475, which was later used for the bypass of Macon.
In addition, Interstate 420 was planned, a southern bypass of Atlanta, of which State Route 154 at East Point should have become part. This bypass was to branch off I-20 west of Atlanta, then parallel it south, then rejoin I-20 east of Atlanta, similar to I-470 in Wheeling, West Virginia.. Interstate 485 was also planned in the 1960s, but was also part of other plans, such as the Stone Mountain Freeway and I-675/State Route 400.
Following on from other metropolitan cities in the United States, the Georgia Department of Transportation has decided to build express lanes on the highways in and around Atlanta to help deal with congestion. The first express lanes opened in 2011 on I-85 northeast of Atlanta. In 2017 and 2018, express lanes opened on I-75, consisting of interchange lanes north and south of Atlanta. For the time being, the express lanes have only been realized in the suburbs and not within I-285. Express lanes are further planned on I-285 on the north side of Atlanta and on State Route 400 north of Atlanta. This will provide express lanes to all Atlanta approach roads from the north.
The traffic volumes on the Downtown Connector have decreased in recent years from 365,000 to 290,000 vehicles.
In Atlanta there are quite a lot of traffic jams, but due to the large number of lanes, long-term stationary traffic is an exception, often it is slow driving or standing still for short pieces and then driving on again. Also, the traffic jam length is usually limited to around connections, especially obsolete nodes. The downtown connector is the busiest in the agglomeration, but usually has 10 to 12 lanes and is usually not completely fixed, just here and there tufts of stationary traffic. One of the larger bottlenecks in the agglomeration is the SR-400, which has quite a lot of traffic jams due to the rapid growth of the suburbs in the north and an outdated interchange with the I-285. Traffic jams are also possible outside the I-285 ring road, as many work centers have been built on this ring road and the ring road has not yet been adapted to this everywhere.
Outside the center of Atlanta there are about 5 larger centers that draw a lot of traffic. These are usually located at nodes. The intensities on the motorway network are quite high, which is also due to the low number of through roads in the secondary road network. Almost all traffic has to take the highway for slightly longer trips. This is a substantial difference with many other cities that have a dense underlying road network with good capacity. The highway network is not very extensive according to the size of the agglomeration, but the large number of lanes on most highways compensates for this. During rush hours, one should count at least one hour for a distance of 50 kilometers.
On January 28-29, 2014, the most extreme congestion in Atlanta’s history occurred. Due to snowfall and the massive closure of governments, companies and schools around noon, there was extreme congestion, with the roads completely iced up. Within 30 minutes, almost the entire highway network changed from free-flow to gridlock. For the first time, all freeways in the Atlanta area were closed in both directions. On some freeways, traffic jams lasted all night, and on some freeways, traffic was blocked for 30 hours at a time. Travel times of more than 7 hours for commuting were observed.
On March 30, 2017, a fire broke out under an I-85 overpass at Piedmont Road, northeast of Downtown Atlanta. I-85 and adjacent GA-13 had to be closed, a segment of the northbound overpass collapsed and the adjacent southbound overpass was so damaged that it had to be demolished. As a result, 222,000 vehicles had to be diverted daily on alternative routes, demonstrating the vulnerability of the limited network of freeways in Atlanta. Due to the incident, a state of emergency was declared, it was called a ‘transportation crisis’.
The intensities are very high in Atlanta, many routes handle more than 200,000 vehicles per day. Previously, the Downtown Connector was the busiest route with 365,000 vehicles per day, but in recent years this has fallen sharply to about 290,000 vehicles, probably due to the emergence of the so-called Edge Cities, where many jobs can be found. The share of Downtown and Midtown as a commuter destination has declined in the last 10 years. traffic is now better distributed, many highways are very busy in both directions during rush hour.
Other busy routes include I-75 just north of I-285 in Marietta with 265,000 vehicles, the double-numbered I-85 and I-285 in College Park with 230,000 vehicles, I-285 in Sandy Springs with 240,000 vehicles, the I-285 at I-85 in northeast Atlanta with 242,000 vehicles, I-85 in Norcross with 260,000 vehicles per day. Interstate 20 is less crowded with a maximum of 180,000 vehicles.