A quadrant roadway intersection adds an additional "quadrant roadway" between two legs of an

intersection In mathematics, the intersection of two or more objects is another object consisting of everything that is contained in all of the objects simultaneously. For example, in Euclidean geometry, when two lines in a plane are not parallel, their ...

. 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 Left-hand traffic (LHT) and right-hand traffic (RHT) are the practices, in bidirectional traffic, of keeping to the left side or to the right side of the road, respectively. They are fundamental to traffic flow, and are sometimes called the ' ...

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. 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

roundabout A roundabout, a rotary and a traffic circle are types of circular intersection or junction in which road traffic is permitted to flow in one direction around a central island, and priority is typically given to traffic already in the junct ...

s or the more complex

single-point urban interchange A single-point urban interchange (SPUI, or ), 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 th ...

designs. 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. A related structure known as a

jughandle A jughandle is a type of ramp or slip road that changes the way traffic turns left at an at-grade intersection (in a country where traffic drives on the right). Instead of a standard left turn being made from the left lane, left-turning traffic ...

accomplishes similar traffic movement from a more compact shape.

Double-quadrant intersections

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.

Quadrant interchanges

interchange Interchange may refer to: Transport * Interchange (road), a collection of ramps, exits, and entrances between two or more highways * Interchange (freight rail), the transfer of freight cars between railroad companies * Interchange station, a rai ...

variant of the quadrant roadway intersection links

grade-separated In civil engineering (more specifically highway 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 tr ...

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 or as a single-loop intersection. This type of junction is common in Germany, where it is called a "partial at-grade intersection" (). 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). Ohashi Junction in

Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

, is also a one-quadrant interchange connecting the elevated Shibuya Route and the underground

Central Circular Route The , signed as Route C2, is one of the routes of the Shuto Expressway system serving the central part of the Greater Tokyo Area. The route is a circumferential highway running through the outer wards of Tokyo. The route is the middle of fou ...

Shuto Expressway The is a network of Toll road, tolled expressways in the Greater Tokyo Area of Japan. It is operated and maintained by the . Most routes are Grade separation, grade separated and have many sharp curves and multi-lane merges that require cauti ...

. With circular ramps built on the southwest quadrant of two expressways, the Ohashi JCT was designed in a four-leveled manner.

Examples

United Kingdom

An example of a left-hand drive double-quadrant interchange can be found in Newport at the intersection of Corporation Road and the

A48 A48 may refer to: * A48 motorway (France), a road connecting the A43 and Grenoble * A48 road (Great Britain), a road connecting Gloucester, England and Carmarthen, Wales * Autovía A-48, a motorway under construction connecting Cadiz and Algecira ...

().

References

{{Road junction types Road junction types