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51-653: 25°46′52″N 80°19′15″W  /  25.781044°N 80.320885°W  / 25.781044; -80.320885 The Dolphin–Palmetto Interchange , also known as 826–836 , is a complex four-level stack interchange in Miami-Dade County , Florida . It primarily serves as a highway interchange between SR 826 (Palmetto Expressway) and SR 836 (Dolphin Expressway), but also has ramps to surface streets such as SR 968 (Flagler Street) and SR 969 (Milam Dairy Road). The reconstruction project

102-577: A Task Force Committee on Transportation to study the state transportation system and recommend major reforms. One of the proposals of the task force was the creation of a State Transportation Board as a permanent advisory board on state transportation policy; the board would later merge into the California Transportation Commission in 1978. In September 1971, the State Transportation Board proposed

153-499: A grid of nearby one-way streets . A common setup is for one mainline to go below grade and another to go above grade. The intersection of the frontage roads is typically at grade or close to it. Two pairs of left-turn connectors are built above these. The Dallas–Fort Worth metroplex has several five-level stacks, most notably the High Five Interchange between US 75 and I-635 ; completed in 2005 and currently

204-634: A new project to add express lanes to the Palmetto Expressway was proposed, to begin construction in 2016. Much work also remains for the Dolphin Expressway. Work took place with phased detours, closures, and openings. All roads involved were kept open throughout construction. Much of the new interchange opened in October 2015, including the two highest flyovers, with completion at that point scheduled for March 2016. By summer 2016,

255-514: A railway line bisecting it at its lowest level. The M4/M25 junction is slightly offset so there is no point where all four levels are directly above each other. M25 (a north–south road at this junction) is offset to the east by approximately 60 metres (200 ft). The junction of the A19 and A66 in Teesside uses a three-level variant, with a 270-degree loop allowing southbound A19 traffic to exit to

306-481: A viaduct, with connector flyover ramps crossing on two further levels. This type of interchange does not usually permit U-turns . The four-level stack creates two "inverse" dual-carriageways —the turn ramps crossing the middle section have traffic driving on the opposite side of oncoming traffic to usual (see diagram for clarity). The first stack interchange was the Four Level Interchange (renamed

357-584: Is a six-level stack on the Yan'an East Road Interchange ( Chinese : 延安东路立交 ) in Puxi, Shanghai, with no dedicated HOV/bus/truck lanes. It is six-level stack because it is formed by two elevated highways, Nanbei Elevated Road and Yan'an Elevated Road with service roads and a footbridge underneath. The centrally located interchange has a central pillar known as the Nine-Dragon Pillar ( 九龙柱 ). The story

408-624: Is also the only true four-level stack in Canada. Highway 407's other proposed four-level stacks at Highway 410 and Highway 404 were reduced to three-level cloverstack interchanges , with loop ramps being built instead of a fourth level of semi-directional ramps. Similarly, the interchange with Highway 427 has four levels but only two semi-directional flyover ramps that cross each other connecting to Highway 427 south of that junction. Two loop ramps link Highway 407 with Highway 427 north of that junction. In Belgium, on

459-514: Is not located near a body of water, most of the city's exports travel through the Port of Durban . The N2 connects Cape Town with Durban and serves the South African cities of Port Elizabeth , East London and George and the towns of Grahamstown , Port Shepstone , Richards Bay and the iSimangaliso Wetland Park . Two busy roads intersect at the junction. A four-level stack interchange

510-570: Is that after several construction accidents, a monk suggested the nine-dragon be welcomed with a bas relief sculpture depicting the dragon. An unusual six-level stack is located at the junction between Interstate 35E and I-635 in Dallas, Texas , and does not contain any service or frontage roads. The interchange features two levels of highway with the top three levels consisting of direct connection ramps and HOV connectors. A single ramp leading from I-635 westbound to I-35E southbound weaves underneath

561-746: The Brussels Ring there are two four-level stack interchanges: The Grand-Bigard and Machelen interchange (only partly in use). In Germany, there is one, the Wetzlarer Kreuz . In Greece, there is also one four stack interchange near Metamorfosi , which connects the A1 and A6 (Attiki Odos) motorways. In the Netherlands there is currently one four-level stack interchange: the Prins Clausplein near The Hague . It forms

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612-673: The Federal-Aid Highway Act of 1956 for the construction of its portion of the Interstate Highway System . Over the next two decades after Collier-Burns, the state "embarked on a massive highway construction program" in which nearly all of the now-extant state highway system was either constructed or upgraded. In hindsight, the period from 1940 to 1969 can be characterized as the "Golden Age" of California's state highway construction program. The history of Caltrans and its predecessor agencies during

663-772: The National Environmental Policy Act and the California Environmental Quality Act forced Caltrans to devote significant time, money, people, and other resources to confronting issues such as "air and water quality, hazardous waste, archaeology, historic preservation, and noise abatement." The devastating 1971 San Fernando earthquake compelled the agency to recognize that its existing design standards had not adequately accounted for earthquake stress and that numerous existing structures needed expensive seismic retrofitting . Maintenance and construction costs grew at twice

714-403: The 1970s, as its institutional focus shifted from highway construction to highway maintenance. The agency was forced to contend with declining revenues, increasing construction and maintenance costs (especially the skyrocketing cost of maintaining the vast highway system built over the past three prior decades), widespread freeway revolts , and new environmental laws . In 1970, the enactment of

765-650: The 20th century was marked by many firsts. It was one of the first agencies in the United States to paint centerlines on highways statewide; the first to build a freeway west of the Mississippi River ; the first to build a four-level stack interchange ; the first to develop and deploy non-reflective raised pavement markers, better known as Botts' dots ; and one of the first to implement dedicated freeway-to-freeway connector ramps for high-occupancy vehicle lanes . In 1967, Governor Ronald Reagan formed

816-784: The Bill Keene Memorial Interchange), built in Los Angeles , California, and completed in 1949, at the junction of US Route 101 (US 101) and State Route 110 (SR 110). Since then, the California Department of Transportation (Caltrans) has built eight more four-level stacks throughout the state of California , notably the Judge Harry Pregerson Interchange , as well as a larger number of three-level and four-level stack– cloverleaf hybrids (where

867-500: The Department of Transportation, of which the most important was the Department of Public Works and its Division of Highways. The California Department of Transportation began official operations on July 1, 1973. The new agency was organized into six divisions: Highways, Mass Transportation, Aeronautics, Transportation Planning, Legal, and Administrative Services. Caltrans went through a difficult period of transformation during

918-643: The I-635 eastbound bridge, making the interchange six levels. The interchange between I-35E and the Sam Rayburn Tollway in Lewisville, Texas , although similar in design to five-level stacks elsewhere in Texas, also qualifies as a six-level stack, since the ramp connecting the eastbound Sam Rayburn Tollway with northbound I-35E goes over the fifth-level ramps connecting I-35E in both directions with

969-530: The Nanjing's Yingtian Street Elevated has one each where it intersects the Inner Ring Road twice. Sometimes a fifth level is added for HOV connectors. An example of this exists in Los Angeles, California , at the Judge Harry Pregerson Interchange . The connector from HOV southbound 110 to HOV westbound 105 can be at the same level as the connector from mixed eastbound 105 to mixed northbound 110, but

1020-631: The Palmetto-to-Dolphin left-hand flyovers on top. As of 2016, it's the largest stack interchange in Miami (surpassing the Midtown Interchange ). Stack interchange A directional interchange , colloquially known as a stack interchange , is a type of grade-separated junction between two controlled-access highways that allows for free-flowing movement to and from all directions of traffic. These interchanges eliminate

1071-597: The Sam Rayburn Tollway. The ramp connecting the westbound Sam Rayburn Tollway with southbound I-35E is on the fourth level of the interchange, going under the fifth-level ramps connecting both directions of I-35E with the Sam Rayburn Tollway. California Department of Transportation Caltrans manages the state's highway system , which includes the California Freeway and Expressway System , supports public transportation systems throughout

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1122-512: The State of California into 12 districts, supervised by district offices. Most districts cover multiple counties ; District 12 ( Orange County ) is the only district with one county. The largest districts by population are District 4 ( San Francisco Bay Area ) and District 7 ( Los Angeles and Ventura counties). Like many state agencies, Caltrans maintains its headquarters in Sacramento , which

1173-508: The beltway's northwest quadrant. The newly reconstructed interchange of I-610 and I-69, with the new I‑610 northbound feeder road built underground and the new I-610 southbound feeder road overpass, is also a five-level stack interchange. Though not a Texas-style stack in the above sense, an unusual stack is nonetheless found in Houston that features more than four levels of traffic but whose fifth level exists in only one direction. In 2011,

1224-454: The city of Hartford . Most of the I‑291 beltway was later cancelled, and the sprawling stack lay dormant for almost 25 years. In 1992 the extension of Connecticut Route 9 to I-84 used the I‑291 right-of-way and some sections of the abandoned interchange. Several ramps still remain unused, including abandoned roadbed for I-291 both north and south of the complex. Four-level stacks are used for

1275-662: The connector from HOV southbound 110 to HOV eastbound 105 needs to be higher level, since it crosses over the former connector. Another case is where connection to nearby arterials suggests that another level may be useful, thus making the interchange more complicated but easier to use. In the Atlanta area, a side ramp forms the fifth level of the Tom Moreland Interchange , colloquially known as Spaghetti Junction , found in DeKalb County, Georgia . There

1326-464: The creation of a state department of transportation charged with responsibility "for performing and integrating transportation planning for all modes ." Governor Reagan mentioned this proposal in his 1972 State of the State address , and Assemblyman Wadie P. Deddeh introduced Assembly Bill 69 to that effect, which was duly passed by the state legislature and signed into law by Reagan later that same year. AB 69 merged three existing departments to create

1377-562: The eastern end of C-470 and the southern end of E-470 . In Thornton, Colorado , there is another stack serving I-25 and E-470 at its northern end as it continues west as the Northwest Parkway . The initial design of Highway 407 had several four-level stack interchanges planned at junctions with existing 400-series highways , but only one example was built: the interchange at Highway 400 in Vaughan, Ontario , which

1428-561: The founding of the Transportation Laboratory and the creation of seven administrative divisions, which are the predecessors of the 12 district offices in use as of 2018 . The original seven division headquarters were located in: In 1913, the California State Legislature began requiring vehicle registration and allocated the resulting funds to support regular highway maintenance, which began

1479-481: The inflation rate in this era of high inflation; the reluctance of one governor after another to raise fuel taxes in accordance with inflation meant that California ranked dead last in the United States in per capita transportation spending by 1983. During the 1980s and 1990s, Caltrans concentrated on "the upgrading, rehabilitation, and maintenance of the existing system," plus occasional gap closure and realignment projects. For administrative purposes, Caltrans divides

1530-568: The interchange the fifth level, as US 90 to I-10 westbound merges onto I-10 before crossing I-610. (None of the frontage roads for these highways cross the interchange itself, and thus do not factor into the complexity of the stack.) More than 40 bridges make up the five-level stack interchange known as the Big ;I between I-40 and I-25 in Albuquerque, New Mexico . China is also home to many Texas-style stack interchanges. For example

1581-574: The interchange was objectively complete. The official announcement came in early October, very near budget ($ 563 million) but a couple years over time. The project included moving a drainage canal and construction of 45 individual bridges, with the interchange serving 430,000 vehicles daily. The main four levels of the interchange are the Palmetto at ground level under the Dolphin Expressway, the Dolphin-to-Palmetto left-hand flyovers, then

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1632-409: The interchanges between: Another well-known stack interchange lies west of Baltimore, Maryland , serving as the junction between I-695 and I-70 . It was originally built for a planned extension of I‑70 into the city. Due to strong opposition, I‑70 ends at a park and ride three miles (4.8 km) east. As a result, the road east of I‑695 sees little traffic compared to the high volumes to and from

1683-954: The junction of the A4 and A12. In the United Kingdom there are three four-level stacks: at the junction of the M4 and M25 near Heathrow Airport in London (the Thorney Interchange ), at the junction of the M23 and M25 to the south of London (the Merstham Interchange), and at the junction of the M4 and M5 near Bristol (the Almondsbury Interchange ). The M4/M25 junction is particularly unusual as it also has

1734-550: The least-used left-turning ramp is built as a cloverleaf-like 270-degree loop). The stack interchange between I-10 and I-405 is a three-level stack, since the semi-directional ramps are spaced out far enough so they do not need to cross each other at a single point as in a conventional four-level stack. The first four-level stack interchange in Texas was built in Fort Worth at the intersection of I-35W and I-30 (originally I-20) near downtown. This interchange, finished in 1958,

1785-582: The next year. In 1921, the state legislature turned the Department of Engineering into the Department of Public Works, which continued to have a Division of Highways. That same year, three additional divisions (now districts) were created, in Stockton, Bishop, and San Bernardino. In 1933, the state legislature enacted an amendment to the State Highway Classification Act of 1927, which added over 6,700 miles of county roads to

1836-449: The opposite road's lanes of travel to complete the turn utilize ramps that make a direct or semi-direct connection. The difference between direct and semi-direct connections is how much the motorist deviates from the intended direction of travel while on the ramp. Direct ramps are shorter and can handle higher traveling speeds than semi-direct. The four-level stack (or simply four-stack ) has one major freeway crossing another freeway with

1887-404: The previously four-level stack interchange between I-610 and I-10 on the city's east side gained a new (though long-planned) level of complexity with the opening of four ramps connecting the new US 90 (Crosby Freeway) to the east, featuring direct movements for the new freeway to and from the southeast quadrant of I-610, to westbound I-10, and from eastbound I-10. It is the latter ramp which gives

1938-414: The problems of weaving , have the highest vehicle capacity, and vehicles travel shorter distances when compared to different types of interchanges. The first directional interchange built in the world was the Four Level Interchange which opened to Los Angeles traffic in 1949. A directional interchange is a grade separated junction between two roads where all turns that require crossing over or under

1989-445: The state and provides funding and oversight for three state-supported Amtrak intercity rail routes ( Capitol Corridor , Pacific Surfliner and San Joaquins ) which are collectively branded as Amtrak California . In 2015, Caltrans released a new mission statement: "Provide a safe, sustainable, integrated and efficient transportation system to enhance California's economy and livability." The earliest predecessor of Caltrans

2040-811: The state highway system. To help manage all the additional work created by this massive expansion, an eleventh district office was founded that year in San Diego. The enactment of the Collier–Burns Highway Act of 1947 after "a lengthy and bitter legislative battle" was a watershed moment in Caltrans history. The act "placed California highway's program on a sound financial basis" by doubling vehicle registration fees and raising gasoline and diesel fuel taxes from 3 cents to 4.5 cents per gallon. All these taxes were again raised further in 1953 and 1963. The state also obtained extensive federal funding from

2091-741: The tallest interchange in the world. Others can be found at the interchanges between State Highway 121 (SH 121) and the Dallas North Tollway , SH 121 and I-35E / US 77 , I-30 and I-35W , I-30 and President George Bush Turnpike and others which are technically five levels but do not fit under a Texas-style stack configuration (i.e. the extra level being located away from the central stack or existing in only one direction). The Houston area has seven five-level stack interchanges along Beltway 8 : at I-10 east and west of downtown, I-69 northeast and southwest of downtown, I-45 north and south of downtown, and US 290 in

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2142-400: The upgraded interchange opened in October 2018. A four-level stack interchange was chosen to serve the increasing volumes of traffic in the uMhlanga/Mount Edgecombe area. In Texas , many stacks contain five levels. They usually have the same configuration as four-level stacks, but frontage roads add a fifth level. The frontage roads usually intersect with traffic lights and are similar to

2193-458: The west. Another four-level stack interchange in the Baltimore area is located at the northeastern junction between I-695 and I-95 . The stack was built as part of a massive I-95 reconstruction project that includes high-occupancy toll lanes (HOT lanes), designed to relieve congestion between Baltimore and its northeastern suburbs. The Springfield Interchange , south of Washington, D.C. ,

2244-621: The westbound A66. The Light Horse Interchange at the junction of the M4 and M7 is a four-level stack interchange in Sydney , New South Wales, Australia. Opened in late 2005, it is the largest in the Southern Hemisphere. The EB Cloete Interchange just outside Durban, South Africa , is another four-level stack interchange. The N3 is the busiest highway in South Africa and a very busy truck route. Because Johannesburg

2295-449: Was a Division of Highways. California voters approved an $ 18 million bond issue for the construction of a state highway system in 1910, and the first California Highway Commission was convened in 1911. On August 7, 1912, the department broke ground on its first construction project, the section of El Camino Real between South San Francisco and Burlingame , which later became part of California State Route 82 . The year 1912 also saw

2346-504: Was chosen to serve the high volumes of traffic. The Mount Edgecombe Interchange is another four-level stack interchange just outside Durban, South Africa , and is the intersection between the N2 (to Durban and KwaDukuza ) and the M41 (to Mount Edgecombe and uMhlanga ). The interchange which was previously a simple diamond interchange was upgraded to a four-level/four-stack interchange, with

2397-411: Was completed in phases from 2012 to 2015-2016, at a cost of about $ 560 million, with related construction beginning in 2009, replacing the old two-level clover-directional interchange. The interchange was considered well beyond safe capacity, serving over 400,000 vehicles per day. The reconstruction was the final phase in a 12-step program to improve the highly trafficked Palmetto Expressway, though in 2014

2448-494: Was known as "The Pretzel" or the "Mixmaster" by locals. The original contract cost was $ 1,220,000. Improvements to the old Mixmaster over the past 60 years include an upgrade to a Texas-style five-level stack exchange (see below). One of the first four-level stack interchanges in the northeastern United States was constructed in the late 1960s over I-84 in Farmington, Connecticut , for the controversial I-291 beltway around

2499-501: Was no longer adequate for the needs of the state's rapidly growing population. After the commissioners submitted their report to the governor on November 25, 1896, the legislature replaced the Bureau with the Department of Highways. Due to the state's weak fiscal condition and corrupt politics, little progress was made until 1907, when the legislature replaced the Department of Highways with the Department of Engineering, within which there

2550-584: Was rebuilt into a four-level stack to accommodate I-95 's transition from the Capital Beltway to its own alignment further south into Virginia. This was necessitated by the inadequacy of the original configuration that was caused by the rerouting of I-95 onto the Beltway after its cancellation within Washington and points north. In Lone Tree, Colorado , there is a four-level stack serving I-25 ,

2601-609: Was the Bureau of Highways, which was created by the California Legislature and signed into law by Governor James Budd in 1895. This agency consisted of three commissioners who were charged with analyzing the roads of the state and making recommendations for their improvement. At the time, there was no state highway system, since roads were purely a local responsibility. California's roads consisted of crude dirt roads maintained by county governments, as well as some paved streets in certain cities, and this ad hoc system

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