Right-in/right-out

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Right-in/right-out (RIRO) and left-in/left-out (LILO) refer to a type of three-way road intersection where turning movements of vehicles are restricted. A RIRO permits only right turns and a LILO permits only left turns. "Right-in" and "left-in" refer to turns from a main road into an intersection (or a driveway or parcel); "right-out" and "left-out" refer to turns from an intersection (or a driveway or parcel) to a main road. [1] [2] [3] RIRO is typical when vehicles drive on the right, and LILO is usual where vehicles drive on the left. This is because minor roads usually connect to the outsides of two-way roads. However, on a divided highway, both RIRO and LILO intersections can occur.

Contents

The remainder of this article refers only to RIRO but applies equally to LILO.

A RIRO intersection differs from a 3/4 intersection (right in/right out/left in) and an unrestricted intersection.

(Lower left) RIRO ramps on and off a divided highway connecting to the Remetinec Roundabout in Zagreb, Croatia. Rotor Zagreb-crop.jpg
(Lower left) RIRO ramps on and off a divided highway connecting to the Remetinec Roundabout in Zagreb, Croatia.
A right-in/right-out intersection at the entrance to the National Institutes of Health along Maryland Route 355 in Bethesda, Maryland, United States. 2007 09 14 - MD355 @ NIH Visitor Access 2.JPG
A right-in/right-out intersection at the entrance to the National Institutes of Health along Maryland Route 355 in Bethesda, Maryland, United States.
King's Highway 11, looking north from overpass, toward South Sparrow Lake Road/Goldstein Road in Severn, Ontario, Canada.
Several characteristics of a RIRO expressway are shown in the image: there is an unbroken median, there are right-in/right-out turns at the side roads, there are businesses with direct right-in/right-out frontage along the highway, and there is a sign indicating that access to the southbound lanes of the highway is via a right turn onto the side road (in this case, by following Goldstein Road to the overpass road, crossing over the highway, then continuing on the overpass road to South Sparrow Lake Road). 11 cl km 141-1 north lg.jpg
King's Highway 11, looking north from overpass, toward South Sparrow Lake Road/Goldstein Road in Severn, Ontario, Canada.
Several characteristics of a RIRO expressway are shown in the image: there is an unbroken median, there are right-in/right-out turns at the side roads, there are businesses with direct right-in/right-out frontage along the highway, and there is a sign indicating that access to the southbound lanes of the highway is via a right turn onto the side road (in this case, by following Goldstein Road to the overpass road, crossing over the highway, then continuing on the overpass road to South Sparrow Lake Road).
King's Highway 11, looking south from same overpass. In addition to the unbroken median, this image shows another characteristic of a RIRO expressway: direct right-in/right-out access to driveways (in this case, residential). 11 cl km 141-1 south lg.jpg
King's Highway 11, looking south from same overpass. In addition to the unbroken median, this image shows another characteristic of a RIRO expressway: direct right-in/right-out access to driveways (in this case, residential).

Design

RIRO is an important tool of access management, itself an important component of transportation planning. A study applying access management guidelines to the redesign of Missouri Route 763 in Columbia, Missouri [4] illustrates how RIRO, combined with signalized intersections designed to permit U-turns, can accommodate high volumes of traffic with low delay and high safety.

The RIRO restriction typically is enforced through physical barriers such as a traffic island in an intersection to direct vehicles into the permitted turn, and to restrict vehicles from traveling through the intersection. The major road itself often has a median separating the two directions of traffic. The restriction may also be achieved by signage, but when a median or other barrier is not present in the median of the major road, RIRO configurations have been found to result in significant violation rates.[ citation needed ]

RIRO roads may also have grade-separated interchanges, but vehicles on these roads do not yield the right-of-way to other vehicles entering the roadway, nor encounter cross traffic. Such roads are sometimes called RIRO expressways. In the United States, they are sometimes called Jersey freeways, due to their prevalence in the state of New Jersey, although they are not limited to that state.

Use

RIRO road configurations are an important tool for access management. General types of RIRO road configuration include limited access roads (divided highways, etc.) and roundabouts. To travel in the restricted direction, vehicles must first turn in the permitted direction, then reverse direction in a U-turn, by going around a roundabout or by going left around a block. RIRO is especially useful where left turns would require crossing in front of oncoming vehicles.

Safety

RIRO configurations generally improve road-traffic safety and efficiency by reducing the number of conflict points between vehicles.

A RIRO configuration may improve safety and operations at one intersection while consequently worsening them at another intersection upstream or downstream.[ citation needed ]

Related Research Articles

Traffic Phenomenon of movement by humans on foot or using vehicles

Traffic comprises pedestrians, vehicles, ridden or herded animals, trains, and other conveyances that use public ways (roads) for travel and transportation.

Roundabout Traffic intersection

A roundabout is a type 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 junction.

Intersection (road) Road junction where two or more roads either meet or cross at grade

An intersection or an at-grade junction is a junction where two or more roads converge, diverge, meet or cross at the same height, as opposed to an interchange, which uses bridges or tunnels to separate different roads. Major intersections are often delineated by gores and may be classified by road segments, traffic controls and lane design.

Three-way junction Type of road intersection with three arms

A three-way junction is a type of road intersection with three arms. A Y junction generally has three arms of equal size. A T junction also has three arms, but one of the arms is generally a minor road connecting to a larger road.

U.S. Route 46 (US 46) is an east–west U.S. Highway completely within the state of New Jersey, running for 75.34 mi (121.25 km), making it the shortest signed, non-spur U.S. Highway. The west end is at an interchange with Interstate 80 (I-80) and Route 94 in Columbia, Warren County on the Delaware River. The east end is in the middle of the George Washington Bridge over the Hudson River in Fort Lee, Bergen County while the route is concurrent with I-95 and US 1-9. Throughout much of its length, US 46 is closely paralleled by I-80. US 46 is a major local and suburban route, with some sections built to or near freeway standards and many other sections arterials with jughandles. The route runs through several communities in the northern part of New Jersey, including Hackettstown, Netcong, Dover, Parsippany-Troy Hills, Wayne, Clifton, Ridgefield Park, Palisades Park, and Fort Lee. It crosses over the Upper Passaic River at several points. The road has been ceremonially named the United Spanish–American War Veterans Memorial Highway.

Michigan left Type of intersection

A Michigan left is an at-grade intersection design that replaces each left turn at an intersection between a (major) divided roadway and a secondary (minor) roadway with the combination of a right turn followed by a U-turn, or a U-turn followed by a right turn, depending on the situation.

Dual carriageway Type of road

A dual carriageway or divided highway is a class of highway with carriageways for traffic travelling in opposite directions separated by a central reservation (BrE) or median (AmE). Roads with two or more carriageways which are designed to higher standards with controlled access are generally classed as motorways, freeways, etc., rather than dual carriageways.

U-turn Driving technique used when someone performs a 180° rotation

A U-turn in driving refers to performing a 180° rotation to reverse the direction of travel. It is called a "U-turn" because the maneuver looks like the letter U. In some areas, the maneuver is illegal, while in others, it is treated as a more ordinary turn, merely extended. In still other areas, lanes are occasionally marked "U-turn permitted" or even "U-turn only."

Diamond interchange 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.

Limited-access road High-speed road with many characteristics of a controlled-access highway (freeway or motorway)

A limited-access road, known by various terms worldwide, including limited-access highway, dual-carriageway, expressway, and partial controlled access highway, is a highway or arterial road for high-speed traffic which has many or most characteristics of a controlled-access highway, including limited or no access to adjacent property, some degree of separation of opposing traffic flow, use of grade separated interchanges to some extent, prohibition of some modes of transport such as bicycles or horses, and very few or no intersecting cross-streets or level crossings. The degree of isolation from local traffic allowed varies between countries and regions. The precise definition of these terms varies by jurisdiction.

Superstreet Type of high capacity intersection

A superstreet, also known as a restricted crossing U-turn (RCUT), J-turn, or reduced conflict intersection (RCI), is a type of road intersection that is a variation of the Michigan left. In this configuration, in contrast to the Michigan left, traffic on the minor road is not permitted to proceed straight across the major road or highway. Drivers on the minor road wishing to turn left or go straight must turn right onto the major road, then, a short distance away, queue (wait) into a designated U-turn lane in the median. When traffic clears, they complete the U-turn and then either go straight or make a right turn when they intersect the other half of the minor road.

Ohio State Route 235

State Route 235 is a 133.2-mile-long (214.4 km) north–south state highway in the western portion of the U.S. state of Ohio. Its southern terminus is at US 68 near the small town of Oldtown just north of Xenia, and its northern terminus is at State Route 65 at the Maumee River nearly 5 miles (8.0 km) east of Grand Rapids, west of Otsego.

Continuous-flow intersection Type of large road intersection

A continuous flow intersection (CFI), also called a crossover displaced left-turn, is an alternative design for an at-grade road junction. Vehicles attempting to turn across the opposing direction of traffic cross before they enter the intersection. No left turn signal in the intersection is then necessary. Instead, vehicles traveling in both directions can proceed, including through vehicles and those turning right or left, when a generic traffic signal/stop sign permits.

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.

Access management, also known as access control, when used in the context of traffic and traffic engineering, generally refers to the regulation of interchanges, intersections, driveways and median openings to a roadway. Its objectives are to enable access to land uses while maintaining roadway safety and mobility through controlling access location, design, spacing and operation. This is particularly important for major roadways intended to provide efficient service to through-traffic movements.

All-way stop Road intersection with stop signs on all approaches

An all-way stop – also known as a four-way stop – is a traffic management system which requires vehicles on all the approaches to a road intersection to stop at the intersection before proceeding through it. Designed for use at low traffic-volume locations, the arrangement is common in the United States, Canada, Mexico, South Africa, and Liberia, as well as in a number of, usually rural, locations in Australia where visibility on the junction approaches is particularly poor. The stop signs at such intersections may be supplemented with additional plates stating the number of approaches.

Seagull intersection Type of three-way road intersection

A seagull intersection or continuous green T-intersection is a type of three-way road intersection, usually used on high traffic volume roads and dual carriageways. This form of intersection is popular in Australia and New Zealand, and sometimes used in the United States and other countries.

Glossary of road transport terms Wikipedia glossary

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.

References

  1. "Title 930 (Transportation, Preconstruction), Rule R930-6 (Access Management)" (PDF). Utah Administrative Code. Utah Department of Transportation. August 2013. Retrieved September 12, 2015.
  2. "Title 930 (Transportation, Preconstruction), Rule R930-6-5 (Access Management, Definitions)". Utah Administrative Code. Utah Department of Administrative Services, Division of Administrative Rules. August 1, 2015. Retrieved September 12, 2015.
  3. "Access Management Manual, Chapter 3 (Guidelines for Public Street and Driveway Connections), 3.4.6 (Restricted Movements and Median Openings)" (PDF). Minnesota Department of Transportation. January 2, 2008. Retrieved September 12, 2015.
  4. Kenny Voss and Trent Brooks and Tim Rogaczewski and Michael Trueblood (2008). "Implementing MoDOT's Access Management Guidelines Along Route 763" (PDF). 7th National Conference on Access Management. Transportation Research Board, Access Management Committee AHB70: 13. Retrieved 2009-06-24.