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73-649: The Interstate Highways in Illinois are all segments of the Interstate Highway System that are owned and maintained by the U.S. state of Illinois . The Illinois Department of Transportation (IDOT), Illinois State Toll Highway Authority (ISTHA), and Skyway Concession Company (SCC) are responsible for maintaining these highways in Illinois. The Interstate Highway System in Illinois consists of 13 primary highways and 11 auxiliary highways which cover 2,248.93 miles (3,619.30 km). The Interstate Highway with

146-522: A concurrency or overlap. For example, I‑75 and I‑85 share the same roadway in Atlanta ; this 7.4-mile (11.9 km) section, called the Downtown Connector , is labeled both I‑75 and I‑85. Concurrencies between Interstate and US Highway numbers are also allowed in accordance with AASHTO policy, as long as the length of the concurrency is reasonable. In rare instances, two highway designations sharing

219-637: A 28-year-old brevet lieutenant colonel, accompanied the trip "through darkest America with truck and tank," as he later described it. Some roads in the West were a "succession of dust, ruts, pits, and holes." As the landmark 1916 law expired, new legislation was passed—the Federal Aid Highway Act of 1921 (Phipps Act). This new road construction initiative once again provided for federal matching funds for road construction and improvement, $ 75 million allocated annually. Moreover, this new legislation for

292-476: A change in the numbering system as a result of a new policy adopted in 1973. Previously, letter-suffixed numbers were used for long spurs off primary routes; for example, western I‑84 was I‑80N, as it went north from I‑80 . The new policy stated, "No new divided numbers (such as I-35W and I-35E , etc.) shall be adopted." The new policy also recommended that existing divided numbers be eliminated as quickly as possible; however, an I-35W and I-35E still exist in

365-569: A circular green indication to show that turns in the direction of the arrow are prohibited, but other movements are allowed. In some jurisdictions, a red arrow prohibits a turn on red . In Europe, if different lanes have differing phases, red, yellow and green traffic lights corresponding to each lane have blacked-out areas in the middle in the shape of arrows indicating the direction(s) drivers in that lane may travel in. This makes it easier for drivers to be aware which traffic light they need to pay attention to. A green arrow may also be provided; when it

438-576: A numbering scheme in which primary Interstates are assigned one- or two-digit numbers, and shorter routes which branch off of longer ones are assigned three-digit numbers where the last two digits match the parent route. The Interstate Highway System is partially financed through the Highway Trust Fund , which itself is funded by a combination of a federal fuel tax and transfers from the Treasury's general fund. Though federal legislation initially banned

511-481: A proposal for an interstate highway system, eventually resulting in the enactment of the Federal-Aid Highway Act of 1956 . Unlike the earlier United States Numbered Highway System, the interstates were designed to be all freeways, with nationally unified standards for construction and signage. While some older freeways were adopted into the system, most of the routes were completely new. In dense urban areas,

584-540: A report called Toll Roads and Free Roads , "the first formal description of what became the Interstate Highway System" and, in 1944, the similarly themed Interregional Highways . The Interstate Highway System gained a champion in President Dwight D. Eisenhower, who was influenced by his experiences as a young Army officer crossing the country in the 1919 Motor Transport Corps convoy that drove in part on

657-409: A single digit prefixed to the two-digit number of its parent Interstate Highway. Spur routes deviate from their parent and do not return; these are given an odd first digit. Circumferential and radial loop routes return to the parent, and are given an even first digit. Unlike primary Interstates, three-digit Interstates are signed as either east–west or north–south, depending on the general orientation of

730-769: A speed limit of 45 mph (70 km/h) because it is a parkway that consists of only one lane per side of the highway. On the other hand, Interstates 15, 80, 84, and 215 in Utah have speed limits as high as 70 mph (115 km/h) within the Wasatch Front , Cedar City , and St. George areas, and I-25 in New Mexico within the Santa Fe and Las Vegas areas along with I-20 in Texas along Odessa and Midland and I-29 in North Dakota along

803-456: A speed limit of 80 mph (130 km/h). Other Interstates in Idaho, Montana, Oklahoma, South Dakota and Wyoming also have the same high speed limits. In some areas, speed limits on Interstates can be significantly lower in areas where they traverse significantly hazardous areas. The maximum speed limit on I-90 is 50 mph (80 km/h) in downtown Cleveland because of two sharp curves with

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876-467: A suggested limit of 35 mph (55 km/h) in a heavily congested area; I-70 through Wheeling, West Virginia , has a maximum speed limit of 45 mph (70 km/h) through the Wheeling Tunnel and most of downtown Wheeling; and I-68 has a maximum speed limit of 40 mph (65 km/h) through Cumberland, Maryland , because of multiple hazards including sharp curves and narrow lanes through

949-603: A turn lane does not normally indicate a prohibition of turns in that direction. Instead, traffic control signs are used to prohibit specific turns. Turn lanes can increase the capacity of an intersection or improve safety. Turn lanes can have a dramatic effect on the safety of a junction. In rural areas, crash frequency can be reduced by up to 48% if left turn lanes are provided on both main-road approaches at stop-controlled intersections. At signalized intersections, crashes can be reduced by 33%. Results are slightly lower in urban areas. Turn lanes are marked with an arrow bending into

1022-534: Is also commonly believed the Interstate Highway System was built for the sole purpose of evacuating cities in the event of nuclear warfare . While military motivations were present, the primary motivations were civilian. The numbering scheme for the Interstate Highway System was developed in 1957 by the American Association of State Highway and Transportation Officials (AASHTO). The association's present numbering policy dates back to August 10, 1973. Within

1095-481: Is known from the crossing at Shibuya Station , Tokyo. In 2020, NHTSA reported that more than 50% of pedestrian deaths in the United States (3,262 total) were attributed to failure to yield the right of way-- which typically occurs at intersections. Poor visibility at junctions can lead to drivers colliding with cyclists and motorcyclists. Some junctions use advanced stop lines which allow cyclists to filter to

1168-446: Is on, drivers heading in the direction of the arrow may proceed, but must yield to all other vehicles. This is similar to the right turn on red in the US. Disadvantages to turn lanes include increased pavement area, with associated increases in construction and maintenance costs, as well as increased amounts of stormwater runoff. They also increase the distance over which pedestrians crossing

1241-525: Is to have the highway route extend from Tamaulipas , Mexico to Ontario , Canada. The planned I-11 will then bridge the Interstate gap between Phoenix, Arizona and Las Vegas, Nevada , and thus form part of the CANAMEX Corridor (along with I-19 , and portions of I-10 and I-15 ) between Sonora , Mexico and Alberta , Canada. Political opposition from residents canceled many freeway projects around

1314-474: The Dallas–Fort Worth metroplex in Texas, and an I-35W and I-35E that run through Minneapolis and Saint Paul , Minnesota, still exist. Additionally, due to Congressional requirements, three sections of I-69 in southern Texas will be divided into I-69W , I-69E , and I-69C (for Central). AASHTO policy allows dual numbering to provide continuity between major control points. This is referred to as

1387-538: The Federal Aid Highway Act of 1956 into law. Under the act, the federal government would pay for 90 percent of the cost of construction of Interstate Highways. Each Interstate Highway was required to be a freeway with at least four lanes and no at-grade crossings. The publication in 1955 of the General Location of National System of Interstate Highways , informally known as the Yellow Book , mapped out what became

1460-603: The Grand Forks area have higher speed limits of 75 mph (120 km/h). As one of the components of the National Highway System , Interstate Highways improve the mobility of military troops to and from airports, seaports, rail terminals, and other military bases. Interstate Highways also connect to other roads that are a part of the Strategic Highway Network , a system of roads identified as critical to

1533-515: The Lincoln Highway , the first road across America. He recalled that, "The old convoy had started me thinking about good two-lane highways... the wisdom of broader ribbons across our land." Eisenhower also gained an appreciation of the Reichsautobahn system, the first "national" implementation of modern Germany's Autobahn network, as a necessary component of a national defense system while he

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1606-1178: The Michigan left / Superstreet (RCUT/MUT) and continuous flow intersection (CFI/DLT), to improve traffic flow, and also interchange types like Diverging diamond interchange (DDI/DCD) design as part of the Federal Highway Administration 's Every Day Counts initiative which started in 2012. Vulnerable road users include pedestrians, cyclists, motorcyclists, and individuals using motorized scooters and similar devices. Compared to people who are in motor vehicles (like cars and trucks), they are much more likely to suffer catastrophic or fatal injuries at an intersection. Intersections generally must manage pedestrian as well as vehicle traffic. Pedestrian aids include crosswalks , pedestrian-directed traffic signals ("walk light") and over / underpasses . Traffic signals can be time consuming to navigate, especially if programmed to prioritise vehicle flow over pedestrians, while over and underpasses which rely on stairs are inaccessible to those who can not climb them. Walk lights may be accompanied by audio signals to aid

1679-643: The National Highway System in the United States . The system extends throughout the contiguous United States and has routes in Hawaii , Alaska , and Puerto Rico . In the 20th century, the United States Congress began funding roadways through the Federal Aid Road Act of 1916 , and started an effort to construct a national road grid with the passage of the Federal Aid Highway Act of 1921 . In 1926,

1752-499: The US Department of Defense . The system has also been used to facilitate evacuations in the face of hurricanes and other natural disasters. An option for maximizing traffic throughput on a highway is to reverse the flow of traffic on one side of a divider so that all lanes become outbound lanes. This procedure, known as contraflow lane reversal , has been employed several times for hurricane evacuations. After public outcry regarding

1825-464: The US Highways , which increase from east to west and north to south). This numbering system usually holds true even if the local direction of the route does not match the compass directions. Numbers divisible by five are intended to be major arteries among the primary routes, carrying traffic long distances. Primary north–south Interstates increase in number from I-5 between Canada and Mexico along

1898-491: The United States Numbered Highway System was established, creating the first national road numbering system for cross-country travel. The roads were state-funded and maintained, and there were few national standards for road design. United States Numbered Highways ranged from two-lane country roads to multi-lane freeways. After Dwight D. Eisenhower became president in 1953, his administration developed

1971-541: The West Coast to I‑95 between Canada and Miami, Florida along the East Coast . Major west–east arterial Interstates increase in number from I-10 between Santa Monica, California , and Jacksonville, Florida , to I-90 between Seattle, Washington , and Boston, Massachusetts , with two exceptions. There are no I-50 and I-60, as routes with those numbers would likely pass through states that currently have US Highways with

2044-559: The Congress Hotel in Chicago. In the plan, Mehren proposed a 50,000-mile (80,000 km) system, consisting of five east–west routes and 10 north–south routes. The system would include two percent of all roads and would pass through every state at a cost of $ 25,000 per mile ($ 16,000/km), providing commercial as well as military transport benefits. In 1919, the US Army sent an expedition across

2117-506: The Interstate Highway System. Assisting in the planning was Charles Erwin Wilson , who was still head of General Motors when President Eisenhower selected him as Secretary of Defense in January 1953. Some sections of highways that became part of the Interstate Highway System actually began construction earlier. Three states have claimed the title of first Interstate Highway. Missouri claims that

2190-485: The Interstate Highway program. The Interstates of Alaska and Puerto Rico are numbered sequentially in order of funding without regard to the rules on odd and even numbers. They also carry the prefixes A and PR , respectively. However, these highways are signed according to their local designations, not their Interstate Highway numbers. Furthermore, these routes were neither planned according to nor constructed to

2263-775: The US to determine the difficulties that military vehicles would have on a cross-country trip. Leaving from the Ellipse near the White House on July 7, the Motor Transport Corps convoy needed 62 days to drive 3,200 miles (5,100 km) on the Lincoln Highway to the Presidio of San Francisco along the Golden Gate . The convoy suffered many setbacks and problems on the route, such as poor-quality bridges, broken crankshafts, and engines clogged with desert sand. Dwight Eisenhower , then

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2336-631: The United States, including: In addition to cancellations, removals of freeways are planned: The American Association of State Highway and Transportation Officials (AASHTO) has defined a set of standards that all new Interstates must meet unless a waiver from the Federal Highway Administration (FHWA) is obtained. One almost absolute standard is the controlled access nature of the roads. With few exceptions , traffic lights (and cross traffic in general) are limited to toll booths and ramp meters (metered flow control for lane merging during rush hour ). Being freeways , Interstate Highways usually have

2409-473: The act was signed, and paving started September 26, 1956. The state marked its portion of I-70 as the first project in the United States completed under the provisions of the new Federal-Aid Highway Act of 1956. The Pennsylvania Turnpike could also be considered one of the first Interstate Highways, and is nicknamed "Grandfather of the Interstate System". On October 1, 1940, 162 miles (261 km) of

2482-648: The cancellation of the Somerset Freeway . This situation was remedied when the construction of the Pennsylvania Turnpike/Interstate 95 Interchange Project started in 2010 and partially opened on September 22, 2018, which was already enough to fill the gap. However, I-70 remains discontinuous in Pennsylvania , because of the lack of a direct interchange with the Pennsylvania Turnpike at

2555-406: The choice of routing destroyed many well-established neighborhoods, often intentionally as part of a program of " urban renewal ". In the two decades following the 1956 Highway Act, the construction of the freeways displaced one million people, and as a result of the many freeway revolts during this era, several planned Interstates were abandoned or re-routed to avoid urban cores. Construction of

2628-650: The city. In some locations, low speed limits are the result of lawsuits and resident demands; after holding up the completion of I-35E in St. Paul, Minnesota , for nearly 30 years in the courts, residents along the stretch of the freeway from the southern city limit to downtown successfully lobbied for a 45 mph (70 km/h) speed limit in addition to a prohibition on any vehicle weighing more than 9,000 pounds (4,100 kg) gross vehicle weight . I-93 in Franconia Notch State Park in northern New Hampshire has

2701-401: The collection of tolls, some Interstate routes are toll roads , either because they were grandfathered into the system or because subsequent legislation has allowed for tolling of Interstates in some cases. As of 2022 , about one quarter of all vehicle miles driven in the country used the Interstate Highway System, which has a total length of 48,890 miles (78,680 km). In 2022 and 2023,

2774-497: The construction and improvement of highways. The nation's revenue needs associated with World War I prevented any significant implementation of this policy, which expired in 1921. In December 1918, E. J. Mehren, a civil engineer and the editor of Engineering News-Record , presented his "A Suggested National Highway Policy and Plan" during a gathering of the State Highway Officials and Highway Industries Association at

2847-407: The contiguous United States, primary Interstates—also called main line Interstates or two-digit Interstates—are assigned numbers less than 100. While numerous exceptions do exist, there is a general scheme for numbering Interstates. Primary Interstates are assigned one- or two-digit numbers, while shorter routes (such as spurs, loops, and short connecting roads) are assigned three-digit numbers where

2920-512: The direction of the turn which is to be made from that lane. Multi-headed arrows indicate that vehicle drivers may travel in any one of the directions pointed to by an arrow. Traffic signals facing vehicles in turn lanes often have arrow-shaped indications. North America uses various indication patterns. Green arrows indicate protected turn phases, when vehicles may turn unhindered by oncoming traffic. Red arrows may be displayed to prohibit turns in that direction. Red arrows may be displayed along with

2993-618: The discontinuity, but they have been blocked by local opposition, fearing a loss of business. The Interstate Highway System has been expanded numerous times. The expansions have both created new designations and extended existing designations. For example, I-49 , added to the system in the 1980s as a freeway in Louisiana , was designated as an expansion corridor, and FHWA approved the expanded route north from Lafayette, Louisiana , to Kansas City, Missouri . The freeway exists today as separate completed segments, with segments under construction or in

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3066-448: The dissemination of public information. As a result, the 2005 evacuation of New Orleans, Louisiana, prior to Hurricane Katrina ran much more smoothly. According to urban legend , early regulations required that one out of every five miles of the Interstate Highway System must be built straight and flat, so as to be usable by aircraft during times of war. There is no evidence of this rule being included in any Interstate legislation. It

3139-492: The eastern end of the concurrency near Breezewood . Traveling in either direction, I-70 traffic must exit the freeway and use a short stretch of US 30 (which includes a number of roadside services) to rejoin I-70. The interchange was not originally built because of a legacy federal funding rule, since relaxed, which restricted the use of federal funds to improve roads financed with tolls. Solutions have been proposed to eliminate

3212-450: The economy. Not just as a public works measure, but for future growth. Clay's committee proposed a 10-year, $ 100 billion program ($ 1.13 trillion in 2023), which would build 40,000 miles (64,000 km) of divided highways linking all American cities with a population of greater than 50,000. Eisenhower initially preferred a system consisting of toll roads , but Clay convinced Eisenhower that toll roads were not feasible outside of

3285-488: The existing, largely non-freeway, United States Numbered Highways system. By the late 1930s, planning had expanded to a system of new superhighways. In 1938, President Franklin D. Roosevelt gave Thomas MacDonald , chief at the Bureau of Public Roads, a hand-drawn map of the United States marked with eight superhighway corridors for study. In 1939, Bureau of Public Roads Division of Information chief Herbert S. Fairbank wrote

3358-426: The federal government, Interstate Highways are owned by the state in which they were built. With few exceptions , all Interstates must meet specific standards , such as having controlled access, physical barriers or median strips between lanes of oncoming traffic, breakdown lanes , avoiding at-grade intersections , no traffic lights , and complying with federal traffic sign specifications. Interstate Highways use

3431-507: The first three contracts under the new program were signed in Missouri on August 2, 1956. The first contract signed was for upgrading a section of US Route 66 to what is now designated Interstate 44 . On August 13, 1956, work began on US 40 (now I-70) in St. Charles County. Kansas claims that it was the first to start paving after the act was signed. Preliminary construction had taken place before

3504-594: The first time sought to target these funds to the construction of a national road grid of interconnected "primary highways", setting up cooperation among the various state highway planning boards. The Bureau of Public Roads asked the Army to provide a list of roads that it considered necessary for national defense. In 1922, General John J. Pershing , former head of the American Expeditionary Force in Europe during

3577-474: The front of a traffic queue which makes them more visible to drivers. A European study found that in Germany and Denmark, the most important crash scenario involving vulnerable road users was: These findings are supported by data elsewhere. According to the U.S. National Highway Traffic Safety Administration , roughly half of all U.S. car crashes occurred at intersections or were intersection related in 2019. In

3650-542: The highest speed limits in a given area. Speed limits are determined by individual states. From 1975 to 1986, the maximum speed limit on any highway in the United States was 55 miles per hour (90 km/h), in accordance with federal law. Typically, lower limits are established in Northeastern and coastal states, while higher speed limits are established in inland states west of the Mississippi River . For example,

3723-542: The highly populated coastal regions. In February 1955, Eisenhower forwarded Clay's proposal to Congress. The bill quickly won approval in the Senate, but House Democrats objected to the use of public bonds as the means to finance construction. Eisenhower and the House Democrats agreed to instead finance the system through the Highway Trust Fund , which itself would be funded by a gasoline tax. In June 1956, Eisenhower signed

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3796-607: The highway now designated I‑70 and I‑76 opened between Irwin and Carlisle . The Commonwealth of Pennsylvania refers to the turnpike as the Granddaddy of the Pikes, a reference to turnpikes . Milestones in the construction of the Interstate Highway System include: The initial cost estimate for the system was $ 25 billion over 12 years; it ended up costing $ 114 billion (equivalent to $ 425 billion in 2006 or $ 618 billion in 2023 ) and took 35 years. The system

3869-454: The inefficiency of evacuating from southern Louisiana prior to Hurricane Georges ' landfall in September 1998, government officials looked towards contraflow to improve evacuation times. In Savannah, Georgia , and Charleston, South Carolina , in 1999, lanes of I-16 and I-26 were used in a contraflow configuration in anticipation of Hurricane Floyd with mixed results. In 2004, contraflow

3942-405: The intersection shown in the diagram, left turn lanes are present in the right-left street. Turn lanes allow vehicles, to cross oncoming traffic (i.e., a left turn in right-side driving countries, or a right turn in left-side driving countries), or to exit a road without crossing traffic (i.e., a right turn in right-side driving countries, or a left turn in left-side driving countries). Absence of

4015-431: The last two digits match the parent route (thus, I-294 is a loop that connects at both ends to I-94 , while I-787 is a short spur route attached to I-87 ). In the numbering scheme for the primary routes, east–west highways are assigned even numbers and north–south highways are assigned odd numbers. Odd route numbers increase from west to east, and even-numbered routes increase from south to north (to avoid confusion with

4088-506: The longest section in Illinois is Interstate 57 at 358.57 miles (577.06 km); the shortest is Interstate 41 at 0.90 miles (1.45 km). Interstate Highway System [REDACTED] The Dwight D. Eisenhower National System of Interstate and Defense Highways , commonly known as the Interstate Highway System , or the Eisenhower Interstate System , is a network of controlled-access highways that forms part of

4161-450: The mainline. Some auxiliary highways do not follow these guidelines, however. The Interstate Highway System also extends to Alaska , Hawaii , and Puerto Rico , even though they have no direct land connections to any other states or territories. However, their residents still pay federal fuel and tire taxes. The Interstates in Hawaii, all located on the most populous island of Oahu , carry

4234-737: The maximum speed limit is 75 mph (120 km/h) in northern Maine, varies between 50 and 70 mph (80 and 115 km/h) from southern Maine to New Jersey, and is 50 mph (80 km/h) in New York City and the District of Columbia. Currently, rural speed limits elsewhere generally range from 65 to 80 miles per hour (105 to 130 km/h). Several portions of various highways such as I-10 and I-20 in rural western Texas, I-80 in Nevada between Fernley and Winnemucca (except around Lovelock) and portions of I-15 , I-70 , I-80 , and I-84 in Utah have

4307-404: The number of fatalities on the Interstate Highway System amounted to more than 5,000 people annually, with nearly 5,600 fatalities in 2022. The United States government's efforts to construct a national network of highways began on an ad hoc basis with the passage of the Federal Aid Road Act of 1916 , which provided $ 75 million over a five-year period for matching funds to the states for

4380-496: The official Interstate Highway standards . On one- or two-digit Interstates, the mile marker numbering almost always begins at the southern or western state line. If an Interstate originates within a state, the numbering begins from the location where the road begins in the south or west. As with all guidelines for Interstate routes, however, numerous exceptions exist. Intersection (road) This article primarily reflects practice in jurisdictions where vehicles are driven on

4453-561: The original Interstate Highway System was proclaimed complete in 1992, despite deviations from the original 1956 plan and several stretches that did not fully conform with federal standards . The construction of the Interstate Highway System cost approximately $ 114 billion (equivalent to $ 618 billion in 2023). The system has continued to expand and grow as additional federal funding has provided for new routes to be added, and many future Interstate Highways are currently either being planned or under construction. Though heavily funded by

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4526-633: The planning phase between them. In 1966, the FHWA designated the entire Interstate Highway System as part of the larger Pan-American Highway System, and at least two proposed Interstate expansions were initiated to help trade with Canada and Mexico spurred by the North American Free Trade Agreement (NAFTA). Long-term plans for I-69 , which currently exists in several separate completed segments (the largest of which are in Indiana and Texas ),

4599-411: The prefix H . There are three one-digit routes in the state ( H-1 , H-2 , and H-3 ) and one auxiliary route ( H-201 ). These Interstates connect several military and naval bases together, as well as the important communities spread across Oahu, and especially within the urban core of Honolulu . Both Alaska and Puerto Rico also have public highways that receive 90 percent of their funding from

4672-775: The right . If not otherwise specified, "right" and "left" can be reversed to reflect jurisdictions where vehicles are driven on the left . One way to classify intersections is by the number of road segments (arms) that are involved. Another way of classifying intersections is by traffic control technology: At intersections, turns are usually allowed, but are often regulated to avoid interference with other traffic. Certain turns may be not allowed or may be limited by regulatory signs or signals, particularly those that cross oncoming traffic. Alternative designs often attempt to reduce or eliminate such potential conflicts. At intersections with large proportions of turning traffic, turn lanes (also known as turn bays ) may be provided. For example, in

4745-524: The route, without regard to the route number. For instance, I-190 in Massachusetts is labeled north–south, while I-195 in New Jersey is labeled east–west. Some looped Interstate routes use inner–outer directions instead of compass directions, when the use of compass directions would create ambiguity. Due to the large number of these routes, auxiliary route numbers may be repeated in different states along

4818-419: The same numbers, which is generally disallowed under highway administration guidelines. Several two-digit numbers are shared between unconnected road segments at opposite ends of the country for various reasons. Some such highways are incomplete Interstates (such as I-69 and I-74 ) and some just happen to share route designations (such as I-76 , I-84 , I‑86 , I-87 , and I-88 ). Some of these were due to

4891-503: The same roadway are signed as traveling in opposite directions; one such wrong-way concurrency is found between Wytheville and Fort Chiswell , Virginia, where I‑81 north and I‑77 south are equivalent (with that section of road traveling almost due east), as are I‑81 south and I‑77 north. Auxiliary Interstate Highways are circumferential, radial, or spur highways that principally serve urban areas . These types of Interstate Highways are given three-digit route numbers, which consist of

4964-438: The street are exposed to vehicle traffic. If a turn lane has a separate signal phase, it often increases the delay experienced by oncoming through traffic. Without a separate phase, left crossing traffic does not get the full safety benefit of the turn lane. Alternative intersection configurations, formerly called unconventional intersections, can manage turning traffic to increase safety and intersection throughput. These include

5037-460: The visually impaired. Medians can offer pedestrian islands, allowing pedestrians to divide their crossings into a separate segment for each traffic direction, possibly with a separate signal for each. Some intersections display red lights in all directions for a period of time . Known as a pedestrian scramble , this type of vehicle all-way stop allows pedestrians to cross safely in any direction, including diagonally. All green for non motorists

5110-490: The war, complied by submitting a detailed network of 20,000 miles (32,000 km) of interconnected primary highways—the so-called Pershing Map . A boom in road construction followed throughout the decade of the 1920s, with such projects as the New York parkway system constructed as part of a new national highway system. As automobile traffic increased, planners saw a need for such an interconnected national system to supplement

5183-541: Was employed ahead of Hurricane Charley in the Tampa, Florida area and on the Gulf Coast before the landfall of Hurricane Ivan ; however, evacuation times there were no better than previous evacuation operations. Engineers began to apply lessons learned from the analysis of prior contraflow operations, including limiting exits, removing troopers (to keep traffic flowing instead of having drivers stop for directions), and improving

5256-422: Was proclaimed complete in 1992, but two of the original Interstates— I-95 and I-70 —were not continuous: both of these discontinuities were due to local opposition, which blocked efforts to build the necessary connections to fully complete the system. I-95 was made a continuous freeway in 2018, and thus I-70 remains the only original Interstate with a discontinuity. I-95 was discontinuous in New Jersey because of

5329-494: Was serving as Supreme Commander of Allied Forces in Europe during World War II . In 1954, Eisenhower appointed General Lucius D. Clay to head a committee charged with proposing an interstate highway system plan. Summing up motivations for the construction of such a system, Clay stated, It was evident we needed better highways. We needed them for safety, to accommodate more automobiles. We needed them for defense purposes, if that should ever be necessary. And we needed them for

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