Алмазная транспортная развязка: типы и особенности

Common type of road junction

A diamond interchange is a common type of road junction, used where a controlled access highway crosses a minor road.

The freeway itself is grade separated from the minor road, one crossing the other over a bridge. Approaching the interchange from either direction, an off ramp diverges only slightly from the freeway and runs directly across the minor road, becoming an on ramp that returns to the freeway in similar fashion. The two places where the ramps meet the road are treated as conventional intersections. In the United States, where this form of interchange is very common, particularly in rural areas, traffic on the off ramp typically faces a stop sign at the minor road, while traffic turning onto the freeway is unrestricted. The diamond interchange uses less space than most types of freeway interchange, and avoids the interweaving traffic flows that occur in interchanges such as the cloverleaf. Thus, diamond interchanges are most effective in areas where traffic is light and a more expensive interchange type is not needed. But where traffic volumes are higher, the two intersections within the interchange often feature additional traffic control measures such as traffic lights and extra lanes dedicated to turning traffic. The at grade variant of the diamond interchange is the split intersection.

A variation of the dumbbell interchange, often called a dogbone interchange (due to its aerial resemblance to a real or toy dog bone), and sometimes also called a double roundabout interchange, more compact examples, which show less of the characteristic "dog bone" shape, are located along Keystone Parkway in Carmel, Indiana, United States. Several interchanges similar to those along Keystone Parkway are being built along the new US 31 freeway under construction in northern Indiana. There are some hybrid interchanges of dumbbell and dogbone having one raindrop and one full roundabout. This is made when the roundabout intersects more roads than the cross street and ramps. Some examples are at exit 38 of the N7 road in Groningen, Netherlands (at ); and Ennis Avenue (National Route 1) at Safety Bay Road (State Route 18 / Tourist Drive 202) on the border of the suburbs of Waikiki and Warnbro in the City of Rockingham, Western Australia (at ). A tennis ball interchange resembles a dogbone interchange, with the difference being that right turning movements (in a country where traffic drives on the left) cut through the roundabouts like a regular diamond interchange instead of going around the roundabout. Such a design is found in Perth, Western Australia, between Roe Highway (State Route 3) and Berkshire Road (at ).

A tight diamond interchange (TDI), also known as a compressed diamond interchange or a tight urban diamond interchange (TUDI), is sometimes used in areas where there is insufficient right of way for a standard diamond interchange. The pair of intersections where the ramps meet the minor road are closely spaced. This spacing forces the turn lanes for each direction to run beside each other, causing the minor road to be wider than it would be if it were a standard diamond. Caltrans classifies this type as Type L 1.

A single point urban interchange (SPUI) is built with a large over or clear underpass providing space for a single traffic signal controlled intersection with the ramps and the cross street. Caltrans classifies this type as Type L 13.

In a diverging diamond interchange (DDI) or (DCD), the two directions of traffic on the non freeway road cross to the opposite side on both sides of the bridge at the freeway to save the third traffic signal phase.

In a three level diamond interchange, the cross street is built in a third level with free flowing traffic as a second arterial road. The intersection is split up into four intersections, handling just two conflicting directions each. Its two level variant is the split diamond interchange. Its at grade variant is the town center intersection (TCI).

A single leg continuous flow intersection (CFI) was built in 2014 in San Marcos, Texas, at the intersection of Aquarena Springs Drive (Loop 82), Interstate 35's southbound frontage road and I 35's southbound to northbound Texas U turn. A two leg CFI, also in San Marcos, was built in 2015 at the intersection of Hopkins Street (State Highway 80), I 35's frontage roads and I 35's Texas U turns. In both intersections, the displaced left turn lanes merge with the Texas U turn lanes.

A split diamond interchange has its ramps "split" between two crossroads, typically with an exit ramp/entrance ramp pair serving each of the crossroads. The crossroads themselves may be one way or two way, and are most often connected by frontage roads, usually one way.

Where HOV lanes are present for carpooling, the ramps of a diamond interchange may be folded to the inside lanes instead of the outside. In urban areas this saves some space as well as requiring only one intersection instead of the two one way intersections, which in rural or suburban areas can be turned into a single point urban interchange. This in turn reduces waiting time for motorists at traffic lights on the smaller road, which may be a large local thoroughfare with heavy traffic.