A quadrant roadway intersection adds an additional "quadrant roadway" between two legs of an intersection. This roadway adds two three-way intersections in addition to the original four-way intersection, moving all left turns (in right-hand traffic countries) or right turns (in left-hand traffic countries) from the main intersection. The design is intended to improve traffic flow by reducing signal timing phases from four to two in the main intersection. The design is intended for intersections where large artery routes meet in an area of dense development and high pedestrian volume. [1] [2]
Proponents also point to a reduction in places where accidents could occur from vehicles potentially crossing paths, as well as a low development cost compared to roundabouts or the more complex single-point urban interchange designs. [1] [3] [4] Opponents point to the increase in points where accidents could occur with merging traffic as well as the non-traditional nature of the design, which has the potential to confuse drivers. Opponents also rebut low-cost claims, pointing to right-of-way and construction costs of the quadrant road. [1] [3]
A related structure known as a jughandle accomplishes similar traffic movement from a more compact shape.
Single-quadrant intersections (pictured above) feature a single quadrant road.
A double-quadrant intersection (or two-quadrant intersection) adds a second quadrant road placed opposite another. [5] [6] [7]
An interchange variant of the quadrant roadway intersection links grade-separated roads, generally a faster road with denser traffic, to a less traveled, slower road, via the quadrant road. This design is referred to as a one-quadrant interchange [8] or as a single-loop intersection. [4] This type of junction is common in Germany, where it is called a "partial at-grade intersection" (German : Teilplangleicher Verkehrsknoten). [9] A so-called two-quadrant interchange also exists, which adds a second quadrant road (although the term "two-quadrant interchange" could be applied to any grade-separated junction in which there are ramps in two quadrants). [10]
Ohashi Junction in Tokyo, Japan, is also a one-quadrant interchange connecting the elevated Shibuya Route and the underground Central Circular Route of Shuto Expressway. With circular ramps built on the southwest quadrant of two expressways, the Ohashi JCT was designed in a four-leveled manner. [11]
A Michigan left or P-turn is an at-grade intersection design that replaces each left (farside) turn at an intersection between a (major) divided roadway and a secondary (minor) roadway with the combination of a right (nearside) turn followed by a U-turn, or a U-turn followed by a right (nearside) turn, depending on the situation. It is in use in numerous countries.
A cloverleaf interchange is a two-level interchange in which all turns are handled by slip roads. To go left, vehicles first continue as one road passes over or under the other, then exit right onto a one-way three-fourths loop ramp (270°) and merge onto the intersecting road. The objective of a cloverleaf is to allow two highways to cross without the need for any traffic to be stopped by traffic lights. The limiting factor in the capacity of a cloverleaf interchange is traffic weaving.
King's Highway 427, also known as Highway 427 and colloquially as the 427, is a 400-series highway in the Canadian province of Ontario that runs from the Queen Elizabeth Way (QEW) and Gardiner Expressway in Toronto to Major Mackenzie Drive in Vaughan. It is Ontario's second busiest freeway by volume and the third busiest in North America, behind Highway 401 and Interstate 405 in California. Like Highway 401, a portion of the route is divided into a collector-express system with twelve to fourteen continuous lanes. Notable about Highway 427 are its several multi-level interchanges; the junctions with the QEW/Gardiner Expressway and Highway 401 are two of the largest interchanges in Ontario and were constructed between 1967 and 1971, while the interchanges with Highway 409 and Highway 407 were completed in 1992 and 1995, respectively.
U.S. Route 35 (US 35) is a United States Highway that runs southeast-northwest for approximately 412 miles (663 km) from the western suburbs of Charleston, West Virginia to northern Indiana. Although the highway is physically southeast-northwest, it is nominally north–south. The highway's southern terminus is in Teays Valley, West Virginia, near Scott Depot, at Interstate 64 (I-64). Its northern terminus is near Michigan City, Indiana, at US 20. The West Virginia portion of the highway is mostly expressway, becoming a freeway shortly before it crosses the Ohio River into Ohio. The Ohio portion has been upgraded to a four-lane highway/freeway between the West Virginia state line and Trotwood, west of Dayton.
In civil engineering, grade separation is a method of aligning a junction of two or more surface transport axes at different heights (grades) so that they will not disrupt the traffic flow on other transit routes when they cross each other. The composition of such transport axes does not have to be uniform; it can consist of a mixture of roads, footpaths, railways, canals, or airport runways. Bridges, tunnels, or a combination of both can be built at a junction to achieve the needed grade separation.
A diamond interchange is a common type of road junction, used where a controlled-access highway crosses a minor road.
A single-point urban interchange, also called a single-point interchange (SPI) or single-point diamond interchange (SPDI), is a type of highway interchange. The design was created in order to help move large volumes of traffic through limited amounts of space safely and efficiently.
A partial cloverleaf interchange or parclo is a modification of a cloverleaf interchange.
The Hanlon Expressway or Hanlon Parkway is a high-capacity at-grade suburban limited-access road connecting Highway 401 with the city of Guelph in the Canadian province of Ontario. The 17 km (11 mi) route travels in a generally north-south direction on the city's west side. It is signed as Highway 6 for its entire length; from Wellington Street to Woodlawn Road it is concurrent with Highway 7. The speed limit alternates between 70 and 80 km/h.
Interstate 395 (I-395) in Washington D.C. and Virginia is a 13.79-mile-long (22.19 km) spur route of I-95 that begins at an interchange with I-95 in Springfield and ends at an interchange with US Route 50 (US 50) in Northwest Washington, D.C. It passes underneath the National Mall near the US Capitol and ends at a junction with US 50 at New York Avenue, roughly one mile (1.6 km) north of the 3rd Street Tunnel. Despite its proximity to I-395 in Maryland, the route is unrelated and unconnected.
In the field of road transport, an interchange or a grade-separated junction is a road junction that uses grade separations to allow for 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 or a limited-access divided highway (expressway), though they are sometimes used at junctions between surface streets.
Alberta Provincial Highway No. 201, officially named Stoney Trail and Tsuut'ina Trail, is an approximately 92-kilometre (57 mi) freeway in Calgary, Alberta. It forms part of the CANAMEX Corridor which connects Calgary to Edmonton and Interstate 15 in the United States via Highways 2, 3, and 4. Planned for a total length of 101 kilometres, the final segment of the ring road is currently under construction to be completed by 2024 at the latest, delayed from an original target of 2022. The freeway serves as a bypass for the congested routes of 16 Avenue N and Deerfoot Trail through Calgary. At its busiest point near Beddington Trail in north Calgary, the six-lane freeway carried nearly 79,000 vehicles per day in 2019.
A junction is where two or more roads meet.
In the field of road transport, a turnaround is a type of junction that allows traffic traveling in one direction on a road to efficiently make a U-turn typically without backing up or making dangerous maneuvers in the middle of the traffic stream. While many junction types permit U-turns, the term turnaround often applies to road junctions built specifically for this purpose.
U.S. Highway 52 (US 52) enters the state of Minnesota at the unincorporated community of Prosper, north of the town of Burr Oak, Iowa. The route is marked north–south in Minnesota along its independent segment from the Iowa state line to downtown St. Paul. US 52 is not signed along the length of its concurrency with Interstate 94 (I-94) from downtown St. Paul to the North Dakota state line at Moorhead and Fargo.
Glenmore Trail is a 22-kilometre (14 mi) expressway in Calgary, Alberta, Canada, named after the reservoir which it crosses. It is a freeway between Sarcee Trail in southwest Calgary to Ogden Road in the southeast, carrying nearly 160,000 vehicles per weekday at its busiest point placing it second only to Deerfoot Trail as the busiest road in Alberta. East of Calgary, Glenmore Trail becomes Highway 560 en route to Langdon.
State Route 500 (SR 500) is a state highway in Clark County, Washington, United States. The east–west highway runs through Vancouver as an expressway and its eastern suburbs as a country road, connecting Interstate 5 (I-5) to I-205 in eastern Vancouver and SR 14 in Camas. SR 500 runs concurrent to SR 503 within Orchards and also uses a section of the county-built Padden Parkway.
Terwillegar Drive is a developing freeway in south-west Edmonton, Alberta. It is under construction, with the majority of its intersection at-grade, it retains its arterial road status. Once completed, it will be the third freeway in Edmonton not to have a highway designation after Groat Road and Wayne Gretzky Drive. South of Windermere Boulevard the roadway goes by 170 Street SW.
Terminology related to road transport—the transport of passengers or goods on paved routes between places—is diverse, with variation between dialects of English. There may also be regional differences within a single country, and some terms differ based on the side of the road traffic drives on. This glossary is an alphabetical listing of road transport terms.
An offset T-intersection is an at-grade road intersection where a conventional four leg intersection is split into two three-leg T-intersections to reduce the number of conflicts and improve traffic flow. Building the offset T-intersections as continuous green T-intersections, there is a single stop on the arterial road, only. A higher volume of through traffic on the cross road, or on unsignalized intersections, a rebuild to a conventional four-leg intersection may be adequate, also when the offset is a few feet only like staggered junctions causing slower traffic for a longer time on the arterial road.
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