Развязки дорог с разделением уровней

Road junction that uses grade separation

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 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 motorway) or a limited access divided highway (expressway), though they are sometimes used at junctions between surface streets.

A system interchange connects multiple controlled access highways, involving no at grade signalised intersections. It is named for its appearance from above, which resembles a four leaf clover. The first cloverleaf outside of North America opened in Stockholm on October15, 1935. Nicknamed Slussen, it was referred to as a "traffic carousel" and 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. 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.

The turbine interchange 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, 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 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 three level roundabout interchange features a grade separated roundabout which handles traffic exchanging between highways. 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 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 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 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 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 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 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 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 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 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 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 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 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 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 the United States opened on July7, 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 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; 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.