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91-598: The Central Freeway begins at a directional "Y" interchange at the west end of Interstate 80 in the South of Market neighborhood, and travels west above Division Street and 13th Street. This interchange also includes access between the Bayshore Freeway , which carries US 101 to the south, and the one-way pair of 9th and 10th Streets. As it approaches the end, US 101 exits onto Mission Street to access Van Ness Avenue , which it follows north to Lombard Street and

182-412: A limited-access highway (expressway), though they are sometimes used at junctions between surface streets. Note: The descriptions of interchanges apply to countries where vehicles drive on the right side of the road. For left-side driving, the layout of junctions is mirrored. Both North American (NA) and British (UK) terminology is included. The concept of the controlled-access highway developed in

273-407: A teardrop shape, with the points facing towards the center of the interchange. Longer ramps are often required due to line-of-sight requirements at roundabouts. A partial cloverleaf interchange (often shortened to the portmanteau, parclo ) is an interchange with loops ramps in one to three quadrants, and diamond interchange ramps in any number of quadrants. The various configurations are generally

364-399: A complex appearance and are often colloquially described as Mixing Bowls , Mixmasters (for a Sunbeam Products brand of electric kitchen mixers ), or as Spaghetti Bowls or Spaghetti Junctions (being compared to boiled spaghetti ). However, they consume a significantly smaller area of land compared to a cloverleaf interchange. A combination interchange (sometimes referred to by

455-435: A design seen in an Argentinian magazine. A system interchange connects multiple controlled-access highways, involving no at-grade signalised intersections. A cloverleaf interchange is a four-legged junction where left turns across opposing traffic are handled by non-directional loop ramps. It is named for its appearance from above, which resembles a four-leaf clover . A cloverleaf is the minimum interchange required for

546-475: A directional T interchange) is typically used when a three-way interchange is required for two or three highways interchanging in semi-parallel/perpendicular directions, but it can also be used in right-angle case as well. Their connecting ramps can spur from either the right or left side of the highway, depending on the direction of travel and the angle. Directional T interchanges use flyover/underpass ramps for both connecting and mainline segments, and they require

637-412: A dumbbell interchange or a dogbone interchange, is similar to the diamond interchange, but uses a pair of roundabouts in place of intersections to join the highway ramps with the crossroad. This typically increases the efficiency of the interchange when compared to a diamond, but is only ideal in light traffic conditions. In the dogbone variation, the roundabouts do not form a complete circle, instead having

728-659: A four-legged system interchange. Although they were commonplace until the 1970s, most highway departments and ministries have sought to rebuild them into more efficient and safer designs. The cloverleaf interchange was invented by Maryland engineer Arthur Hale, who filed a patent for its design on May   24, 1915. The first one in North America opened on December   15, 1929, in Woodbridge, New Jersey, connecting New Jersey Route   25 and Route   4 (now U.S. Route   1/9 and New Jersey Route   35). It

819-519: A full list of prefixes, see California postmile § Official postmile definitions ). Segments that remain unconstructed or have been relinquished to local control may be omitted. The entire route is in San Francisco . Directional %22Y%22 interchange In the field of road transport , an interchange (American English) or a grade-separated junction (British English) is a road junction that uses grade separations to allow for

910-667: A moderate amount of land and moderate costs since only two levels of roadway are typically used. Their name derives from their resemblance to the capital letter T, depending upon the angle from which the interchange is seen and the alignment of the roads that are interchanging. It is sometimes known as the "New England Y", as this design is often seen in the northeastern United States, particularly in Connecticut. This type of interchange features directional ramps (no loops, or weaving right to turn left) and can use multilane ramps in comparatively little space. Some designs have two ramps and

1001-478: A pair of ramps would split to the east, taking downtown traffic to and from the one-way pair of Bush and Pine Streets. At Clay Street, the freeway would descend to meet the rising terrain, ending at Broadway just east of Van Ness Avenue as a single level depressed roadway . A short tunnel would curve northwest to a portal in Van Ness Avenue north of Broadway, taking traffic onto Van Ness Avenue towards

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1092-454: A parclo AB features a loop ramp approaching the crossroad in one direction, and beyond the crossroad in the opposing direction, as in the example image. A diverging diamond interchange (DDI) or double crossover diamond interchange (DCD) is similar to a traditional diamond interchange, except the opposing lanes on the crossroad cross each other twice, once on each side of the highway. This allows all highway entrances and exits to avoid crossing

1183-463: A patent for the design of a cloverleaf interchange on May   24, 1915, though the conceptual roadwork was not realised until a cloverleaf opened on December   15, 1929, in Woodbridge, New Jersey , connecting New Jersey Route 25 and Route 4 (now U.S. Route 1/9 and New Jersey Route 35 ). It was designed by Philadelphia engineering firm Rudolph and Delano, based on

1274-623: A result, the only freeway within city limits is the Trans-Canada Highway, which passes through the north-eastern corner of the city. Very few major roads have been built in decades although the population would likely have doubled. The conflicting opinions of the City of Vancouver's residents, as represented by their successive councils, and the British Columbia Ministry of Transportation continue in 2013. Many of

1365-439: A safer modification of the cloverleaf design, due to a partial or complete reduction in weaving, but may require traffic lights on the lesser-travelled crossroad. Depending on the number of ramps used, they take up a moderate to large amount of land, and have varying capacity and efficiency. Parclo configurations are given names based on the location of and number of quadrants with ramps. The letter A denotes that, for traffic on

1456-543: A small angle and meet the non-freeway at almost right angles. These ramps at the non-freeway can be controlled through stop signs , traffic signals , or turn ramps. Diamond interchanges are much more economical in use of materials and land than other interchange designs, as the junction does not normally require more than one bridge to be constructed. However, their capacity is lower than other interchanges and when traffic volumes are high they can easily become congested. A double roundabout diamond interchange, also known as

1547-401: A three-level semi-directional T at Highway 407 and a two-level semi-directional T at Highway 401 . Service interchanges are used between a controlled-access route and a crossroad that is not controlled-access. A full cloverleaf may be used as a system or a service interchange. A diamond interchange is an interchange involving four ramps where they enter and leave the freeway at

1638-509: A three-way interchange. However, in a semi-directional T, some of the splits and merges are switched to avoid ramps to and from the passing lane , eliminating the major disadvantage of the directional T. Semi-directional T interchanges are generally safe and efficient, though they do require more land and are costlier than trumpet interchanges. Semi-directional T interchanges are built as two- or three-level junctions, with three-level interchanges typically used in urban or suburban areas where land

1729-442: A toll road meets another toll road or a free highway. They are also useful when most traffic on the terminating highway is going in the same direction. The turn that is used less often would contain the slower loop ramp. Trumpet interchanges are often used instead of directional or semi-directional T or Y interchanges because they require less bridge construction but still eliminate weaving. A full Y-interchange (also known as

1820-422: A traditional stack interchange. A three-level roundabout interchange features a grade-separated roundabout which handles traffic exchanging between highways. The ramps of the interchanging highways meet at a roundabout , or rotary, on a separated level above, below, or in the middle of the two highways. These interchanges can also be used to make a "linking road" to the destination for a service interchange, or

1911-446: Is a 3-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 4-level stack. Stacks are significantly more expensive than other four-way interchanges are due to the design of the four levels; additionally, they may suffer from objections of local residents because of their height and high visual impact. Large stacks with multiple levels may have

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2002-428: Is an alternative four-way directional interchange. The turbine interchange requires fewer levels (usually two or three) while retaining directional ramps throughout. It features right-exit, left-turning ramps that sweep around the center of the interchange in a clockwise spiral . A full turbine interchange features a minimum of 18 overpasses, and requires more land to construct than a four-level stack interchange; however,

2093-477: Is braided when at least one of the roadways reverses sides. It seeks to make left and right turns equally easy. In a pure braided interchange, each roadway has one right exit, one left exit, one right on-ramp, and one left on-ramp, and both roadways are flipped. The first pure braided interchange was built in Baltimore at Interstate 95 at Interstate 695 ; however, the interchange was reconfigured in 2008 to

2184-470: Is more expensive. In a three-level semi-directional T, the two semi-directional ramps from the terminating highway cross the surviving highway at or near a single point, which requires both an overpass and underpass. In a two-level semi-directional T, the two semi-directional ramps from the terminating highway cross each other at a different point than the surviving highway, necessitating longer ramps and often one ramp having two overpasses. Highway 412 has

2275-624: Is now the new portion of Yaletown, where the roundhouse is. It would likely have been adjacent to or above the current Pacific Avenue, between Old and New Yaletown. The Dunsmuir tunnel, a former freight railroad line of the CPR would also have been part of the freeway. This tunnel is now used by the SkyTrain Expo Line , a rapid transit line using the Bombardier Innovia Metro technology developed for Toronto. An attempt

2366-612: The 1969 Melbourne Transportation Plan , mostly by those in the affected inner-city areas. In 1974, 150 residents protesting plans for the F-19 freeway through Collingwood put themselves in front of construction equipment in an attempt to halt construction. In 1978, protesters rallied to defend Gardiners Creek in Kooyong , which was in the path of the South Eastern Freeway . In 1984, over 100 protesters rallied against

2457-494: The 1978 Commonwealth Games in which Edmonton built an LRT system instead. In Halifax, Nova Scotia the construction of an elevated waterfront freeway, Harbour Drive, was halted in the 1970s after local opposition to the proposed destruction of many historic buildings. All that remains of the project today is the Cogswell Interchange , a massive concrete structure widely considered a barrier between sections of

2548-626: The Bonaventure Expressway with an urban boulevard in the Griffintown neighborhood. A large area of the Saint-Roch neighbourhood was destroyed to make room for Autoroute 440 (A-440) in the late 1960s. A-440 was supposed to run aside the cliff to connect the other section of the highway, but this part was never built due to local opposition. This led to a massive 6-lane structure ending on Rue Saint-Vallier. This structure

2639-472: The Dutch Parliament had to decide whether to build or not. A narrow majority of 71 was in favour, 69 opposed. Parts of Amelisweerd were occupied by activists after the decision. The encampment, established by the activists, was evacuated by police and 465 trees were cut down and bulldozed. At the same time a procedure opposing the tree felling was started, however, a municipality lawyer reported that

2730-988: The Federal Highway Administration in August 1965 and by the state in 1968. There was a plan promulgated in February 1962 to relieve traffic congestion on the Golden Gate Bridge by constructing a "San Francisco-Tiburon Bridge" from Van Ness Ave. at Aquatic Park in San Francisco north across the Golden Gate Strait to Tiburon to connect with the Redwood Highway , which would have been anchored on Angel Island . Had this bridge actually been constructed, it would have probably been eventually necessary to construct

2821-539: The Golden Gate Bridge . Along with the Embarcadero and Broadway Tunnel , which were listed for rebuilding as ground-level expressways rather than the freeway ( Embarcadero Freeway ) that was later partially built and demolished, the Central Freeway would have provided a full traffic distributor loop around downtown. The route was also included in the 1955 city master plan, by then extending north beyond

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2912-441: The Golden Gate Bridge . The remainder of the freeway is signed as exit 434B from US 101, and comes to the surface at Market Street and Octavia Boulevard , the latter continuing north to Oak and Fell Streets, a one-way pair west to Golden Gate Park . No traffic from Market Street is allowed to turn onto the freeway, but traffic from the freeway may turn right onto Market. The first opportunity for traffic that instead continues onto

3003-712: The IJtunnel , along with the plans of the Amsterdam Metro around Nieuwmarkt . It would have demolished thousands of houses and monuments on its path, and therefore it led to the Nieuwmarkt riots in 1975. The metro was built, but the highway plans were removed. In Utrecht , plans to build the A27 led to years of protests and juridical procedures, with a big demonstration occurring in October 1978. Eventually, in 1982,

3094-556: The James MacDonald Bridge . This explains the bizarre look of the James MacDonald Bridge's nearby interchange, which was only meant to be temporary, however serves in its original state today. The plan would have also built a Downtown Freeway Loop encircling the city's downtown core , with freeways reaching out to all corners of Edmonton via present-day Fort Road/ Manning Drive /Wayne Gretzky Drive as

3185-710: The Provincial Legislature and stated, "Cities were built for people and not cars. If we are building a transportation system to serve the automobile, the Spadina Expressway would be a good place to start. But if we are building a transportation system to serve people, the Spadina Expressway is a good place to stop." The expressway plan was dead; construction of the Spadina Expressway ended. The successful outcome of inspired protests of varying degrees to other expressway projects in Toronto including

3276-519: The South of Market neighborhood actually got a wider freeway, closer to ground level, in the space where the double-decked road had been. The newer section of the Central Freeway between Mission Street and Market Street still remains unsigned, but is maintained by Caltrans. Between early 2010 and 2013, when it was partially redeveloped for housing, a 2.2-acre site between Laguna, Oak, Fell, and Octavia Streets in Hayes Valley that had been ramps for

3367-608: The Thousand Islands Parkway and onward to the Quebec border. Plans were announced to extend the freeway along Huron Church Road to the Ambassador Bridge , but residents and business owners along the route protested and killed the plan, leaving the freeway's terminus at Highway 3 . Since then, traffic had increased, and a new bridge and freeway was needed. Expropriation of nearby properties began in

3458-400: The controlled-access highway , the loop ramps are located in advance of (or approaching ) the crossroad, and thus provide an onramp to the highway. The letter B indicated that the loop ramps are beyond the crossroad, and thus provide an offramp from the highway. These letters can be used together when opposite directions of travel on the controlled-access highway are not symmetrical, thus

3549-403: The "inside" through road (on the same side as the freeway that ends) crossing each other at a three-level bridge. The directional T interchange is preferred to a trumpet interchange because a trumpet requires a loop ramp by which speeds can be reduced, but flyover ramps can handle much faster speeds. The disadvantage of the directional T is that traffic from the terminating road enters and leaves on

3640-521: The 1920s and 1930s in Italy, Germany, the United States, and Canada. Initially, these roads featured at-grade intersections along their length. Interchanges were developed to provide access between these new highways and heavily-travelled surface streets. The Bronx River Parkway and Long Island Motor Parkway were the first roads to feature grade-separations. Maryland engineer Arthur Hale filed

3731-601: The Board of Supervisors banned any new freeway construction north of Market Street ; a city task force recommended its replacement with a surface boulevard in 1995. Caltrans closed the double-deck freeway north of Mission Street for rebuilding in late 1996. A fight began between the primarily Chinese American residents of western San Francisco (the Richmond District and the Sunset District ), who favored

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3822-583: The Caltrans plan to rebuild it because it provided easy access for prospective customers to get to their businesses in the Richmond and Sunset districts, and the primarily White and Black Hayes Valley local residents, who regarded the freeway as urban blight, and were supported by Mayor Willie Brown . Caltrans reopened the northbound (lower) deck to Fell Street in 1997, but did not put a route designation on that deck; several initiatives were passed to remove

3913-452: The Central Freeway and other nearby elevated freeways. Except where prefixed with a letter, postmiles were measured on the road as it was in 1964 , based on the alignment that existed at the time, and do not necessarily reflect current mileage. R reflects a realignment in the route since then, M indicates a second realignment, L refers to an overlap due to a correction or change, and T indicates postmiles classified as temporary ( for

4004-810: The Northeast Freeway, St. Albert/Mark Messier Trail as the Northwest Freeway, 111 Street as the South Freeway, 91 Street as the Southeast Freeway and would have the designation of Highway 2, and a freeway running along present-day River Valley Road/ Stony Plain Road and 100 Avenue /Baseline Road, which was to be named the Jasper Freeway. While the projects were approved, they were ultimately killed because of cost and

4095-475: The Quebec government presented a project of a new tunnel from Lévis to downtown Quebec City. The tunnel would have two exit connecting to A-440 which leads to opposition from Saint-Roch residents who do not want more cars in the neighbourhood. During the 1950s, Toronto experienced the same sort of urban sprawl that was sweeping through the United States. Suburbs grew along existing highway corridors, stretching

4186-563: The Scarborough, Richview, Crosstown and East Metro Expressway Projects. This led to none of the other planned expressways ever being built. Instead of expressways, Davis and his new Minister of Transport, Charles MacNaughton , outlined the " GO-Urban " plan, an Intermediate Capacity Transit System that will serve the Greater Toronto Area in place of expressways. This led to the development of Bombardier Innovia Metro . By

4277-485: The United States opened on July   7, 2009, in Springfield, Missouri , at the junction of Interstate 44 and Missouri Route 13 . A single-point urban interchange (SPUI) or single-point diamond interchange (SPDI) is a modification of a diamond interchange in which all four ramps to and from a controlled-access highway converge at a single, three-phase traffic light in the middle of an overpass or underpass. While

4368-531: The boulevard to leave it is east on Page Street. Before the Loma Prieta earthquake, the freeway continued beyond Fell Street and then curved northeast, with the northbound side ending at a ramp to Golden Gate Avenue and Franklin Street, and the southbound level touching down to the northwest at Turk and Gough Streets. Until 2007, this land remained mainly undeveloped, filled primarily by parking lots . However,

4459-401: The bridges are generally short in length. Coupled with reduced maintenance costs, a turbine interchange is a less costly alternative to a stack. A windmill interchange is similar to a turbine interchange, but it has much sharper turns, reducing its size and capacity. The interchange is named for its similar overhead appearance to the blades of a windmill . A variation of the windmill, called

4550-705: The bypass will suffer the loss of their heritage. In 1969, plans called for Alberta Highway 2 to continue into Edmonton , akin to the Deerfoot Trail in Calgary , using 91 Street then descending into the Mill Creek Ravine . However, residents along Mill Creek as well as many others who did not wish to have portions of the river valley destroyed at the expense of a freeway opposed the plans and, as such, they were never completed. The only portions to be completed were 91 Street, Wayne Gretzky Drive and

4641-517: The citizens changed. By the mid-1960s, there was a growing awareness that the growth of the suburbs led to a flight of capital from the city cores, resulting in the urban decay being seen throughout the US. Additionally, several of the chosen routes ran through densely settled neighbourhoods, including some of the more upscale areas of Toronto, like Forest Hill and the University of Toronto . While

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4732-467: The city east and west, and then northward along the various provincial superhighways . These highways ended at the city limits, however, and there was little route capacity within the city itself. This caused enormous traffic problems within the city, and a network of new highways to address the problem became part of the Official Plan in 1959. As construction of the network started, the mood of

4823-411: The city off from the river. Many historic homes were demolished to make way for the western section of the autoroute, but the eastern section was reconceived as a tunnel skirting the southern edge of the downtown core and a sunken expressway along the inland edge of the old city. Since then, Old Montreal has undergone significant rehabilitation and is now a desirable residential and commercial district and

4914-473: The city's leading tourist area. Part of the sunken expressway has been covered over (see Quartier international de Montréal ) and the section immediately north of Montreal City Hall is also slated to be covered. Another cancelled project would have seen Rue Berri converted into a north–south expressway, demolishing much of the Plateau Mont-Royal district. Only the portion south of Rue Cherrier

5005-545: The city. Its demolition is currently planned. Several areas were destroyed to make room for highways in the 1960s and 1970s. At that time, a historical preservation movement involving figures such as Sandy van Ginkel and Phyllis Lambert prevented a project to run the Ville-Marie Expressway along the waterfront of the Old Port, which would have demolished much of the then-unloved Old Montreal and cut

5096-507: The compact design is safer, more efficient, and offers increased capacity—with three light phases as opposed to four in a traditional diamond, and two left turn queues on the arterial road instead of four—the significantly wider overpass or underpass structure makes them more costly than most service interchanges. Since single-point urban interchanges can exist in rural areas, such as the interchange of U.S. Route 23 with M-59 in Michigan ;

5187-537: The creation of a new basic road as a service interchange. Trumpet interchanges may be used where one highway terminates at another highway, and are named as such for to their resemblance to trumpets . They are sometimes called jug handles . These interchanges are very common on toll roads , as they concentrate all entering and exiting traffic into a single stretch of roadway, where toll plazas can be installed once to handle all traffic, especially on ticket-based tollways . A double-trumpet interchange can be found where

5278-574: The demolition of The Rocks historic precinct and The Domain gardens for freeway developments. In 1989, 200 protesters rallied against a proposed north-west tollway. In 1991, 150 anti-freeway protesters rallied outside Parliament House. In 1995, over 400 people protested the M2 Hills Motorway . In 2009, Tasmanian Aboriginals conducted protests against the construction of the Brighton Bypass . They have stated that construction of

5369-448: The diverging windmill, increases capacity by altering the direction of traffic flow of the interchanging highways, making the connecting ramps much more direct. There also is a hybrid interchange somewhat like the diverging windmill in which left turn exits merge on the left, but it differs in that the left turn exits use left directional ramps. A braided or diverging interchange is a two-level, four-way interchange. An interchange

5460-453: The elevated freeway was temporarily converted into Hayes Valley Farm . With a grant from the Mayor's Office of Economic and Workforce Development, raised beds using cardboard as mulch were constructed on the road bed and potted fruit trees and bee hives added. In 2022, State Senator Scott Wiener submitted a letter to a Caltrans district director requesting a study to investigate demolition of

5551-536: The former Broadway terminus to the proposed Golden Gate Freeway near Lombard Street . The first piece, connecting the Bayshore Freeway with Mission Street , opened March 1, 1955, at about the same time as the Bayshore. The part of the Central Freeway to the one-way pair of Golden Gate Avenue and Turk Street opened in April 1959, and became part of U.S. Route 101 (and Legislative Route 2 ) via this one-way pair to

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5642-415: The heyday of the automobile have since been removed at public demand. One of the most prominent was a large interchange at the corner of Avenue du Parc and Avenue des Pins, which had long impeded pedestrian access along a major entryway into Mount Royal Park . The elevated structure was demolished in the early 2000s and replaced with a simpler, at-grade intersection. Another project nearing completion replaces

5733-400: The last tree had already been cut down. Thus the short-term procedure failed to achieve its aim. After the motorway was completed in 1986, more congestion arose on the motorway. In 2009, new plans were made to extend the road from 2x4 lanes to 2x6 or even 2x7. The start of the construction in 2011 led again to protests, with clearly visible banners along the motorway. There were protests when

5824-730: The late 2000s for Highway 401's extension to a new border crossing, the Gordie Howe International Bridge connecting with I-75 in Detroit . Construction of the Rt. Hon. Herb Gray Parkway , much of it below-grade, began in late 2011 and was completed in 2015. The bridge is planned to open in 2025. In Amsterdam in the 1970s, plans existed for a highway between the end of the A2 at the President Kennedylaan to

5915-409: The lower deck. The final compromise took a two-way freeway down to ground level at Market Street, where Octavia Boulevard  – a widened Octavia Street on the former freeway right-of-way — would continue to Fell Street. The completed project opened on September 9, 2005. Unfortunately, this compromise design has resulted in creating one of the most dangerous intersections in the city. Furthermore,

6006-417: The movement of traffic between two or more roadways or highways , using a system of interconnecting roadways to permit traffic on at least one of the routes to pass through the junction without interruption from crossing traffic streams. It differs from a standard intersection , where roads cross at grade . Interchanges are almost always used when at least one road is a controlled-access highway (freeway) or

6097-484: The old route on Van Ness Avenue. In January of that year, as one of the opening events in the freeway revolts , the San Francisco Board of Supervisors passed Resolution 45-59, removing the remainder of the Central Freeway and most other proposed freeways from the city's highway plan. Interstate 80 , which had been assigned to the Central Freeway southeast of the proposed Panhandle Freeway, was truncated by

6188-594: The opposite direction of travel and saves one signal phase of traffic lights each. The first DDIs were constructed in the French communities of Versailles ( A13 at D182), Le Perreux-sur-Marne ( A4 at N486) and Seclin ( A1 at D549), in the 1970s. Despite the fact that such interchanges already existed, the idea for the DDI was "reinvented" around 2000, inspired by the freeway-to-freeway interchange between Interstate 95 and I-695 north of Baltimore . The first DDI in

6279-608: The opposition was growing, Jane Jacobs moved to Toronto after having successfully rallied groups to cancel the construction of the Lower Manhattan Expressway in New York City . Applying the same formula in Toronto, Jacobs rallied local groups to oppose development of the Spadina Expressway project, while twice being arrested in the process. On June 3, 1971, Premier Bill Davis rose in

6370-526: The parcels were sold off to developers in the 2010s and as of 2020, most of it has been converted into a mix of affordable and market-rate housing. The 1948 Transportation Plan for San Francisco, prepared by De Leuw, Cather and Company, included the Central Freeway. This elevated roadway would begin at the Bayshore Freeway  – the approach to the San Francisco–Oakland Bay Bridge  – near Division Street and head west and north around

6461-513: The passing lane, so the semi-directional T interchange (see below) is preferred. The interchange of Highway 416 and Highway 417 in Ontario, constructed in the early 1990s, is one of the few directional T interchanges, as most transportation departments had switched to the semi-directional T design. As with a directional T interchange, a semi-directional T interchange uses flyover (overpass) or underpass ramps in all directions at

6552-641: The periphery of downtown San Francisco . This portion would include junctions with the Mission Freeway (south and southwest along Mission Street to Daly City ) at the southwest corner and the Panhandle Freeway (west through the Panhandle into Golden Gate Park ) along the west side. After swinging northeast and back north to the east side of Van Ness Avenue (continuing as a double-decked structure between Van Ness Ave. and Polk Street ),

6643-744: The plan was intended to link an eight-lane freeway from the Trans-Canada Highway through the East End, destroying much of Chinatown . Before it was stopped, Vancouver's Hogan's Alley neighbourhood was largely demolished. The complete proposal in reports prepared by Swan-Wooster included a six lane tunnel to North Vancouver. An elevated freeway would have run along the Burrard Inlet waterfront, right through property where two Fairmont hotels and many other buildings have since been built. Another elevated freeway would have run through what

6734-540: The planning or construction of highways , freeways , expressways , and other civil engineering projects that prioritize motor vehicle traffic over pedestrian movement or other considerations. Freeway revolts first took place in developed countries during the 1960s and 1970s, in response to plans for the construction of new freeways, as advocated for by the highway lobby . Some highways were abandoned or scaled back due to widespread public opposition, especially in neighborhoods that would be disrupted or displaced by

6825-543: The portmanteau, cloverstack ) is a hybrid of other interchange designs. It uses loop ramps to serve slower or less-occupied traffic flow , and flyover ramps to serve faster and heavier traffic flows. If local and express ways serving the same directions and each roadway is connected righthand to the interchange, extra ramps are installed. The combination interchange design is commonly used to upgrade cloverleaf interchanges to increase their capacity and eliminate weaving. Some turbine-stack hybrids: The turbine interchange

6916-467: The problem of weaving, and due to the semi-directional flyover ramps and directional ramps, they are generally safe and efficient at handling high traffic volumes in all directions. A standard stack interchange includes roads on four levels, also known as a 4-level stack, including the two perpendicular highways, and one more additional level for each pair of left-turn ramps. These ramps can be stacked (cross) in various configurations above, below, or between

7007-696: The proposed freeways, and by those opposed to freeways' other negative effects . Freeway revolts have gained renewed interest in the 21st century, with activists pushing to bury highways underground or remove freeways from cities to repair the damage to neighborhoods displaced by highway construction in the 20th century. While anti-freeway/anti-road activism in Australia has not been as vocal as in North America, small-scale revolts against freeway construction have occurred in Sydney and Melbourne, with many protesting toll collection. Melbourne saw protests against

7098-512: The proposed northern section of the Central Freeway from Turk Street north to Aquatic Park in order to adequately funnel traffic to it. In 1989, the Loma Prieta earthquake damaged the northern part of the elevated roadway, and in 1992 Caltrans removed the freeway north of Fell Street and rerouted U.S. 101 to exit at Mission Street and onto the portion of Van Ness Avenue between the Central Freeway and Turk Street/Golden Gate Avenue. That year

7189-455: The rightmost lane. After demerging from right-turning traffic, they complete their left turn by crossing both highways on a flyover ramp or underpass. The penultimate step is a merge with the right-turn on-ramp traffic from the opposite quadrant of the interchange. Finally, an on-ramp merges both streams of incoming traffic into the left-bound highway. As there is only one off-ramp and one on-ramp (in that respective order), stacks do not suffer from

7280-421: The road is extended. US 70 and US 17 west of New Bern, North Carolina is an example. A stack interchange is a four-way interchange whereby a semi-directional left turn and a directional right turn are both available. Usually, access to both turns is provided simultaneously by a single off-ramp. Assuming right-handed driving, to cross over incoming traffic and go left, vehicles first exit onto an off-ramp from

7371-468: The suburbs also want more automobile access to Vancouver. The city resists additional cars entering from the suburbs. The province continues to build bridges and freeways throughout the region, but they end at the city limits. Windsor, Ontario is an interesting case of freeway revolt that was later partially reversed. By 1965, the MTO had completed construction of Highway 401 from the south end of Windsor to

7462-642: The term single-point diamond interchange is considered the correct phrasing. Single-point interchanges were first built in the early 1970s along U.S. Route 19 in the Tampa Bay area of Florida , including the SR 694 interchange in St. Petersburg and SR 60 in Clearwater . Freeway revolts Highway revolts (also freeway revolts , expressway revolts , or road protests ) are organized protests against

7553-588: The time the prototype was ready for service in the early 1980s, changes in the provincial government ended support for the entire GO-Urban project. Only a single short demonstration line was built in Toronto, the Scarborough RT . In Vancouver , a freeway project that began with the construction of the Georgia and Dunsmuir Viaducts in the Strathcona neighborhood was stopped by activists and residents;

7644-502: The two interchanging highways. This makes them distinct from turbine interchanges, where pairs of left-turn ramps are separated but at the same level. There are some stacks that could be considered 5-level; however, these remain four-way interchanges, since the fifth level actually consists of dedicated ramps for HOV /bus lanes or frontage roads running through the interchange. The stack interchange between I-10 and I-405 in Los Angeles

7735-628: The widening of Punt Road to become the Hoddle Highway . Many of the unbuilt freeways were eventually cancelled by change of government, but some projects were later resurrected. An umbrella organisation known as the Coalition Against Freeway Expansion (CAFE) was formed in 1994, and in the following year, 14 of its activists were arrested whilst protesting an Eastern Freeway extension and the partial demolition of Alexandra Parade. The aggressive police response

7826-552: Was built. In recent years, protests took place regarding a proposal to extend the Ville-Marie in the axis of Rue Notre-Dame Est, as an 8-lane entrenched highway that would separate the residential neighborhood of Hochelaga-Maisonneuve from the St. Lawrence River. The current plan is to widen the current 4-lane road into a six-lane "urban boulevard" rather than converting it into a full-scale expressway. Some large road projects from

7917-540: Was considered a revolutionary design at the time of its construction. A cloverleaf offers uninterrupted connections between two roads but suffers from weaving issues. Along the mainline, a loop ramp introduces traffic prior to a second loop ramp providing access to the crossroad, between which ingress and egress traffic mixes. For this reason, the cloverleaf interchange has fallen out of favour in place of combination interchanges . Some may be half cloverleaf containing ghost ramps which can be upgraded to full cloverleafs if

8008-558: Was criticised, and led to the eventual disbandment of the group. One of the largest protests occurred in 2008 in Kensington , one of the areas most impacted by the proposed East-West road connection ; it drew wider support due to opposition to the Eddington Transport Report . Sydney freeway protests have included large-scale green bans in the 1970s, which prevented freeway proposals that would have required

8099-596: Was designed by Philadelphia engineering firm Rudolph and Delano based on a design seen in an Argentinian magazine. The first cloverleaf in Canada opened in 1938 at the junction of Highway 10 and what would become the Queen Elizabeth Way . The first cloverleaf outside of North America opened in Stockholm on October   15, 1935. Nicknamed Slussen , it was referred to as a "traffic carousel" and

8190-495: Was made in 1995 to revive part of the project, adding three lanes of traffic to the north shore; it was also killed by public protest. Successive city councils in the 1970s and 1980s prohibited the construction of freeways as part of a long-term plan. This was taken as far as refusing to have a cloverleaf where the provincially authorized and funded Oak Street Bridge entered the city. It was allowed to enter directly onto Oak Street, but no other approaches were allowed for decades. As

8281-566: Was partially demolished in 2007, along with two ghost ramps reaching the cliff for an abandoned tunnel below downtown. The highway was also supposed to run right through the Saint Lawrence River , until pressure from Beauport residents forced its rerouting to the shore. The elevated six-lane freeway opened in 1974 in Saint-Roch and the ground level 6-to-8 lanes from Saint-Roch to Autoroute 40 (A-40) opened in 1982. In 2020,

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