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. 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.
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.
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 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.
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.
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 or by going around a roundabout. RIRO is especially useful where left turns would require crossing in front of oncoming vehicles.
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.
The Arlington Expressway, which carries the unsigned State Road 10A (SR 10A) and mostly also the signed State Road 115 in Jacksonville, Florida, is a freeway that heads east from Downtown Jacksonville over the Mathews Bridge to Atlantic Boulevard (State Road 10) at the Regency Square Mall.Crowchild Trail
Crowchild Trail is a major expressway in west of Calgary, Alberta, Canada. The segment from 12 Mile Coulee Road to 16 Avenue NE (Trans-Canada Highway, Highway 1) is designated as Highway 1A by Alberta Transportation.Intersection (road)
This article primarily reflects practice in jurisdictions where vehicles are driven on the right. If not otherwise specified, "right" and "left" can be reversed to reflect jurisdictions where vehicles are driven on the left.
An intersection is an at-grade junction where two or more roads meet or cross. Intersections may be classified by number of road segments, traffic controls, and/or lane design.Lloyd Expressway
The Lloyd Expressway is a major east-west traffic artery located in Vanderburgh County, Indiana. The route primarily runs through Evansville, Indiana, reaching from Interstate 69 on the east side of the city to the Posey County line west of the city limits. West of US 41, the expressway is signed as Indiana State Road 62 (SR 62). East of US 41, it is signed as Indiana State Road 66 (SR 66).Macleod Trail
Macleod Trail is a major road in Calgary, Alberta, Canada. It is a six- to eight-lane principal arterial road extending from downtown Calgary to the south of the city, where it merges into Highway 2. South of Anderson Road, Macleod Trail is an expressway and is slated to be upgraded to a freeway in the future. It is named for its destination to the south, Fort Macleod.Maryland Route 18
Maryland Route 18 (MD 18) is a state highway in the U.S. state of Maryland. The state highway runs 20.37 miles (32.78 km) from the beginning of state maintenance at Love Point east to MD 213 in Centreville. MD 18 is the main east–west local highway on Kent Island and east to Centreville, serving the centers of Stevensville, Chester, Kent Narrows, Grasonville, and Queenstown that are bypassed by U.S. Route 50 (US 50) and US 301. What is signed as MD 18 is actually a set of four suffixed highways: MD 18A, MD 18B, MD 18S, and MD 18C. There are also several unsigned segments of MD 18 scattered along the length of the signed portions.
What is now MD 18 was first paved in the 1910s from Centreville to Queenstown along with short segments in Grasonville and Chester. Gaps in the Stevensville–Queenstown highway were filled throughout the 1920s, leaving only a crossing of Kent Narrows to be completed in the early 1930s. MD 18 between Stevensville and Love Point was constructed in the early 1930s. The Stevensville–Queenstown highway was designated part of MD 404, while the highways on both ends to Love Point and Centreville were designated MD 18. US 50 replaced MD 404 when the former highway was extended east of Annapolis in 1949. When US 50 was relocated as a divided highway between the Chesapeake Bay Bridge and Queenstown in the early 1950s, MD 18 was assigned to the bypassed highway. Since the mid-1980s, several suffixed sections of MD 18 have been created, relocated, or received new designations due to expansion of US 50 and US 301 to a freeway.Maryland Route 575
Maryland Route 575 (MD 575) is a state highway in the U.S. state of Maryland. Known as Worcester Highway, the state highway runs 2.70 miles (4.35 km) from U.S. Route 113 (US 113) in Friendship north to MD 589 and US 113 in Showell. MD 575 is the old alignment of US 113 in northern Worcester County. The state highway was assigned in 2000 when US 113 was relocated as a four-lane divided highway through the area. As part of the overall project to expand US 113 to four lanes from Berlin to the Delaware state line, 14 unsigned auxiliary routes of MD 575 were designated on old alignments or service roads between 2002 and 2004.New Jersey Route 17
Route 17 is a state highway in Bergen County, New Jersey, United States, that provides a major route from the George Washington Bridge, Lincoln Tunnel and other northeast New Jersey points to the New York State Thruway at Suffern, New York. It runs 27.20 mi (43.77 km) from Route 7/County Route 507 in North Arlington north to the New York border along Interstate 287 in Mahwah, where New York State Route 17 continues into New York. Between Route 7 and Route 3 in Rutherford, Route 17 serves as a local road. From Route 3 north to the junction with U.S. Route 46 in Hasbrouck Heights, the road is a suburban arterial with jughandles. The portion of Route 17, from US 46 to Interstate 287 near the state line in Mahwah, is a limited-access road with all cross traffic handled by interchanges, and many driveways and side streets accessed from right-in/right-out ramps from the right lane. For three miles (5 km) north of Route 4, well over a hundred retail stores and several large shopping malls line the route in the borough of Paramus. The remainder of this portion of Route 17 features lighter suburban development. The northernmost portion of Route 17 in Mahwah runs concurrent with Interstate 287 to the New York border.
Prior to 1927, the route was designated as Route 17N, which was to run from Newark to the New York state line. This route had followed various local streets, including the Franklin Turnpike north of Hackensack. In 1927, Route 17N became Route 2, which was designated along the portion of Route 17N between Route 7 in North Arlington to the New York border near Suffern, New York. This route was moved to a multilane divided highway alignment north of Rutherford by 1937. Route 2 became Route 17 in 1942 to match the designation of New York State Route 17 for defense purposes during World War II. The entire Route 17 corridor was once planned to be a freeway until the 1960s and later plans to extend the route south of Route 3 to Interstate 280 in 1972 and to the New Jersey Turnpike in 1987 both failed. Over the years, the portion of Route 17 north of Route 3 has seen many improvements, including the widening of much of the road to six lanes and the removal of most at-grade intersections in the 1950s as well as more recent improvements to the interchanges with Route 4 in Paramus in 1999 and Essex Street on the Lodi/Maywood border in 2008. The route is currently undergoing improvements between Route 3 and U.S. Route 46 and is expected to see improvements from Williams Avenue in Hasbrouck Heights to south of Route 4 in Paramus.New Jersey Route 4
Route 4 is a state highway in Bergen County and Passaic County, New Jersey, United States. The highway stretches 10.83 mi (17.43 km) from Route 20 (McLean Boulevard) in Paterson east to an interchange with Interstate 95, U.S. Route 1/9, U.S. Route 46, and U.S. Route 9W at the George Washington Bridge approach in Fort Lee.
The route is a four- to six-lane 40 to 50 mph (64 to 80 km/h) divided highway its entire length, with the portion east of the Route 208 interchange in Fair Lawn a limited-access road consisting of interchanges and right-in/right-out intersections with many businesses along the road, particularly in Paramus, where the route passes through a major shopping area consisting of numerous malls, Hackensack, Englewood, and Fort Lee. West of Route 208, the route is a surface arterial that runs through commercial areas. Route 4 intersects many important roads, including Route 208 in Fair Lawn and the Garden State Parkway and Route 17 in Paramus. The highway is officially named the Mackay Highway, but is rarely referred to as such.
Originally legislated to traverse the state from Cape May to the George Washington Bridge, Route 4 was reduced to its current alignment in 1953. Today's stretch of the route was completed by 1934; the state planned to upgrade it to a full freeway, but plans never materialized. Despite this, the route has seen improvements, such as to the interchanges with Route 17 in 1999 and with Route 208 in 2002.
Route 4 is a heavily used commuter, retail, and long-distance artery. As well as providing a critical commuter route from the Hudson Valley and Bergen’s County into New York City via the George Washington Bridge, it gives New Yorkers access to popular shopping areas such as Garden State Plaza and Bergen Town Center, and forms part of the straightest route from New York City and Long Island to Upstate and Western New York destinations. Locally, especially west of the Hackensack River, it is seen as a socioeconomic dividing line between wealthier, more affluent suburbs like Ridgewood and Oradell to the north, and more urbanized, industrialized, working-class areas like Hackensack to the south. Trucks are permitted on Route 4, but due to its narrow lanes and short on/off ramps, tractor trailers tend to prefer nearby I-80 when traveling through the area.Ontario Highway 115
King's Highway 115, commonly referred to as Highway 115 is a provincially maintained highway in the Canadian province of Ontario that connects Peterborough with Toronto via Highway 401. The highway begins at a junction with Highway 401 southwest of Newcastle and ends at an at-grade intersection with Highway 7 east of Peterborough.
Highway 115 is part of the Algonquin Trail and concurrent with Highway 35 from its southern terminus in Clarington to Enterprise Hill, where it veers towards Peterborough and Highway 35 continues north into the Kawarthas. It is also part of the Trans-Canada Highway from the interchange with Highway 7 south of Springville, Ontario to the northern terminus of the highway. Highway 115 is a freeway northeast of Enterprise Hill and a Right-in/right-out (RIRO) expressway south of it, featuring short ramps with abrupt right turns to and from the highway. By January 2010, exit numbers were added to the freeway section north of the Highway 35 concurrency.Overpass
An overpass (called an overbridge in the United Kingdom and Australia, and a flyover in the United Kingdom as well as some other Commonwealth countries) is a bridge, road, railway or similar structure that crosses over another road or railway. An overpass and underpass together form a grade separation. Stack interchanges are made up of many overpasses.Taconic State Parkway
The Taconic State Parkway (often called the Taconic or the TSP and known administratively as New York State Route 987G or NY 987G) is a 104.12-mile (167.56 km) divided highway between Kensico Dam and Chatham, the longest parkway in the U.S. state of New York. It follows a generally northward route midway between the Hudson River and the Connecticut and Massachusetts state lines, along the Taconic Mountains. Its southernmost three miles (4.8 km) are a surface road; from the junction with the Sprain Brook Parkway northward it is a limited-access highway. It has grade-separated interchanges from that point to its northern terminus; in the three northern counties, there are also at-grade intersections, many with closed medians, allowing only right-in/right-out turns. It is open only to passenger vehicles, as with other parkways in New York, and maintained by the state Department of Transportation (NYSDOT), the fourth agency to have that responsibility.
Franklin D. Roosevelt, who had long envisioned a scenic road through the eastern Hudson Valley, was instrumental in making it a reality as a way to provide access to existing and planned state parks in the region. Its winding, hilly route was designed by landscape architect Gilmore Clarke to offer scenic vistas of the Hudson Highlands, Catskills, and Taconic regions. The bridges and now-closed service areas were designed to be aesthetically pleasing. It has been praised for the beauty of not only the surrounding landscape and views it offers, but the way the road itself integrates with and presents them.
It was completed in its present form in the early 1960s. In 2005 the entire highway, including its supporting structures, was listed on the National Register of Historic Places in recognition of its historic importance in the development of parkways in the 20th century, and Roosevelt's role in creating it. It is the second-longest continuous road listed on the Register after Virginia's Skyline Drive, and the longest limited-access highway.The parkway continues to provide access to several state parks, including one named for Roosevelt. It has also become an important regional artery, one of the primary routes to northern New England and upstate New York from New York City and Long Island. The southern sections, particularly in Westchester County, have become a commuter route into the city for residents who moved into towns that became suburbanized as a result of the parkway. The state and regional transportation planners have worked to adapt to this change since the 1940s.Taschereau Boulevard
Taschereau Boulevard is a major suburban boulevard located on the south shore of Montreal, Quebec, Canada. It is a section of Quebec Route 134 and runs from Longueuil to Candiac (junction of Autoroute 15). It is named after the prominent Quebec family that included former premier Louis-Alexandre Taschereau. At 17.5 km (10.9 mi), it is one of the longest commercial arteries in Canada. It serves the heart of an area with an estimated population of 400,000.Between its approach near the Jacques-Cartier Bridge and the Quebec Route 112 and Quebec Route 116 expressway that links Longueuil with the Saint-Hubert and Saint-Bruno sectors, Route 134 is a 6-lane expressway with interchanges to local areas within Longueuil and LeMoyne. In some sections, it is designed as a right-in/right-out freeway with at-grade intersections on the municipality-maintain lane (usually right lane) to local streets from one side of the highway.Three-way junction
A 3-way junction (or 3-way intersection) is a type of road intersection with three arms. A Y junction (or Y intersection) generally has 3 arms of equal size. A T junction (or T intersection) also has 3 arms, but one of the arms is generally a minor road connecting to a larger road.Turnaround (road)
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 (to reverse course and travel the opposite direction) 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. Route 301 in Maryland
U.S. Route 301 (US 301) in the state of Maryland is a major highway that runs from Delaware to the Governor Harry W. Nice Memorial Bridge into Virginia. It passes through three of Maryland's four main regions: the Eastern Shore, the Baltimore-Washington Metropolitan Area, and Southern Maryland. US 301 serves mainly as a bypass of Baltimore and Washington from Delaware to Virginia.U.S. Route 50 in Maryland
U.S. Route 50 (US 50) is a major east–west route of the U.S. Highway system, stretching just over 3,000 miles (4,800 km) from Ocean City, Maryland on the Atlantic Ocean to West Sacramento, California. In the U.S. state of Maryland, US 50 exists in two sections. The longer of these serves as a major route connecting Washington, D.C. with Ocean City; the latter is the eastern terminus of the highway. The other section passes through the southern end of Garrett County for less than 10 miles (16 km) as part of the Northwestern Turnpike, entering West Virginia at both ends. One notable section of US 50 is the dual-span Chesapeake Bay Bridge across the Chesapeake Bay, which links the Baltimore–Washington metropolitan area with the Eastern Shore region, allowing motorists to reach Ocean City and the Delaware Beaches.
US 50 has received numerous upgrades during its existence in Maryland, including the construction of the John Hanson Highway (which is also the unsigned Interstate 595), its extension onto the Eastern Shore and replacement of U.S. Route 213 due to the construction of the Chesapeake Bay Bridge, and the full conversion of the eastern segment of the route into a four-lane divided highway. Many of the older alignments of US 50 are still part of the Maryland and US highway systems, such as U.S. Route 50 Business in Salisbury, Maryland. US 50 continues to be upgraded on the Eastern Shore.Virginia State Route 150
State Route 150 (SR 150) is a state highway in the U.S. state of Virginia. Known as Chippenham Parkway, the state highway runs 15.19 miles (24.45 km) from Interstate 95 (I-95) and SR 895 in Bensley north to Parham Road and River Road near Tuckahoe in Henrico County. SR 150 is a four- to six-lane circumferential highway that connects the Chesterfield County suburbs of Richmond with western Henrico County and, via SR 895, eastern Henrico County and Richmond International Airport. The highway is a freeway except for a short stretch east of SR 147 in Richmond. SR 150 has junctions with all of the radial highways south of the James River, including I-95, U.S. Route 1, US 301, US 360, US 60, and SR 76.Washington State Route 500
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.
The highway originally followed Fourth Plain Boulevard, a local road built in the 1820s by fur traders and later extended east to Camas in the 1920s. It was added to the state highway system in 1937 as Secondary State Highway 8A (SSH 8A) and widened by the state government in the late 1960s. SSH 8A was replaced by SR 500 in the 1964 state highway renumbering, concurrent with state plans to build a parallel freeway to relieve traffic congestion on Fourth Plain Boulevard.
The state government constructed an expressway for SR 500 in the 1970s and 1980s, including an interchange with I-205 near the new Vancouver Mall. The expressway included several at-grade intersections with traffic signals that led to a high rate of rear-end collisions. The state government began converting these intersections into grade-separated interchanges in the 1990s, with the final right-in/right-out junctions opened in 2018. The eastern section of SR 500 in Orchards on Fourth Plain Boulevard was replaced with the Padden Parkway in 2005.