California State Route 178
State Route 178 is a route that exists in two constructed segments. The gap in between segments is connected by various local roads and State Route 190 through Death Valley National Park. SR 178 serves many different purposes, it connects Downtown Bakersfield with East Bakersfield and Lake Isabella. It is one of two crossings over the Sierra Nevada south of Yosemite, connecting the southern San Joaquin Valley with the upper Mojave Desert and the Owens Valley; this provides access to Death Valley National Park. If the unconstructed portion were built, it would provide an easy route between Ridgecrest and Las Vegas, via Pahrump, Nevada. SR 178 is part of the California Freeway and Expressway System, through Bakersfield and Ridgecrest is part of the National Highway System, a network of highways that are considered essential to the country's economy and mobility by the Federal Highway Administration, it is eligible for the State Scenic Highway System, but it is not designated as a scenic highway by the California Department of Transportation.
The first segment starts at State Route 99 just west of Downtown Bakersfield. The road continues as 24th Street but splits at B Street, utilizing 24th Street for westbound traffic and 23rd Street for eastbound traffic through Downtown Bakersfield. SR 178 becomes a freeway; the freeway travels east as it enters Northeast Bakersfield. A mile east of the Morning Drive interchange, the freeway segment ends with the first at-grade intersection at Canteria Drive. From here, the road narrows to a 4-lane highway; the highway continues through the rural, but growing Rio Bravo section of Bakersfield, crossing SR 184. Turning northeast, the route continues to the mouth of Kern Canyon. For the next 8 miles, the route is a narrow 2-lane road, as it ascends the lower Sierra Nevada. Average speed is 35 mph, with steep dropoffs. After 8 miles, the road becomes a much gentler 4-lane, 60 ft. expressway. The route continues east and reaches the town of Lake Isabella, just south of the Lake Isabella Reservoir; the road expands to a divided freeway through Lake Isabella, before narrowing to a 2-lane conventional highway at the intersection with Lake Isabella Boulevard.
The road continues to wind until it ascends to an elevation of over 5,000 feet. The highway descends from the mountains to its junction with State Route 14, it proceeds eastward across US 395 into the town of Ridgecrest. The constructed highway ends at the turnoff for the Trona Pinnacles National Natural Landmark; the second segment resumes four miles west of Salisberry Pass in the southeasterly part of Death Valley National Park in Inyo County at what had been the former boundary of Death Valley National Monument until 1994. It meets up with State Route 127. SR 178 branches northward from SR 127 to the California-Nevada State Line. In Nevada, the roadway continues as State Route 372 ending at State Route 160 near the center of Pahrump in Nye County; the segment of State Route 178 from State Route 127 to the California-Nevada state line, as well as all of Nevada State Route 372, are both known as the Charles Brown Highway. Charles Brown, a former California State Legislator, was a major proponent for the incorporation of the segment of State Route 178 between State Route 14 and the California-Nevada state line into the California Highway System.
SR 178 was one of the routes created with the third bond act of 1919. It defined a route 202 miles long between Freeman Junction through Bakersfield. Freeman does not exist today; the route was defined as Legislative Route 57. The 1919 bond act created the first segment of LRN 58; the route was extended several times since 1919. In 1933, the final segment was added to LRN 58, which created a route from US 101 near Santa Margarita to the Nevada state line via Bakersfield. Construction on the route between Bakersfield and Isabella through Kern Canyon started in 1922. Progress moved as sheer rock walls had to be blasted with dynamite. In 1931, 9 years after construction started, the 26-mile highway segment was completed. In 1933, with the creation of signed routes, portions of LRN 57 and LRN 58 would be signed as Route 178. LRN 58 would be signed between Route 33 and US 99, LRN 57 would be signed between US 99 and US 6. In 1947, LRN 212 was created, defined to run from LRN 23 near Inyokern, east to the Nevada state line.
It was an unsigned route. From 1950 to 1953, a portion of SR 178 in Lake Isabella was rerouted around the Isabella Auxiliary Dam; the dam was built over the old route and parts of it are inundated by Isabella Lake. The new route goes over the dam's southern abutment and along the shoreline of Isabella Lake toward Onyx. In 1964, all of the California routes were renumbered. LRN 58 was dropped from Route 178 and combined with the eastern portion of the decommissioned US 466 to create SR 58; the remaining Route 178 was combined with LRN 212 to create SR 178. It was defined to start at SR 99 in Bakersfield, but that year it was changed to start in Bakersfield; this change was done to avoid a cosign with SR 58 along 23rd/24th St. After SR 58 was moved to the freeway south of Brundage Lane in 1976, SR 178 was extended west to SR 99. Construction on the initial freeway in Bakersfield was completed in 1968, it ran from M St, on the eastern edge of Downtown, through East Bakersfield to Haley Street
Federal Highway Administration
The Federal Highway Administration is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program and the Federal Lands Highway Program, its role had been performed by the Office of Road Inquiry, Office of Public Roads and the Bureau of Public Roads. The organization has a complicated history; the Office of Road Inquiry was founded in 1893. In 1905 that organization's name was changed to the Office of Public Roads which became a division of the United States Department of Agriculture; the name was changed again to the Bureau of Public Roads in 1915 and to the Public Roads Administration in 1939. It was shifted to the Federal Works Agency, abolished in 1949 when its name reverted to Bureau of Public Roads under the Department of Commerce. With the coming of the bicycle in the 1890s, interest grew regarding the improvement of streets and roads in America; the traditional method of putting the burden on maintaining roads on local landowners was inadequate.
New York State took the lead in 1898, by 1916 the old system had been discarded everywhere area. Demands grew for local and state government to take charge. With the coming of the automobile after 1910, urgent efforts were made to upgrade and modernize dirt roads designed for horse-drawn wagon traffic; the American Association for Highway Improvement was organized in 1910. Funding came from automobile registration, taxes on motor fuels, as well as state aid. In 1916, federal-aid was first made available to improve post-roads, promote general commerce. Congress appropriated $75 million over a five-year period, with the Secretary of Agriculture in charge through the Bureau of Public Roads, in cooperation with the state highway departments. There were 2.4 million miles of rural dirt rural roads in 1914. The increasing speed of automobiles, trucks, made maintenance and repair high-priority item. Concrete was first used in 1893, expanded until it became the dominant surfacing material in the 1930s. Federal aid began in 1917.
From 1917 through 1941, 261,000 miles of highways were built with federal aid, cost $5.31 billion. Federal funds totaled $3.17 billion, state-local funds were $2.14 billion. The FHWA was created on October 15, 1966. In 1967 the functions of the Bureau of Public Roads were transferred to the new organization, it was one of three original bureaus along with the'Bureau of Motor Carrier Safety' and the'National Highway Safety Bureau'. The FHWA’s role in the Federal-aid Highway Program is to oversee federal funds used for constructing and maintaining the National Highway System; this funding comes from the federal gasoline tax and goes to state departments of transportation. FHWA oversees projects using these funds to ensure that federal requirements for project eligibility, contract administration and construction standards are adhered to. Under the Federal Lands Highway Program, the FHWA provides highway design and construction services for various federal land-management agencies, such as the Forest Service and the National Park Service.
In addition to these programs, the FHWA performs and sponsors research in the areas of roadway safety, highway materials and construction methods, provides funding to local technical assistance program centers to disseminate research results to local highway agencies. The FHWA publishes the “Manual on Uniform Traffic Control Devices”, used by most highway agencies in the United States; the MUTCD specifies such things as the size and height of traffic signs, traffic signals and road surface markings. The Federal Highway Administration is overseen by an Administrator appointed by the President of the United States by and with the consent of the United States Senate; the Administrator works under the direction of the Secretary of Transportation and Deputy Secretary of Transportation. The internal organization of the FHWA is as follows: Administrator Executive Director Office of Infrastructure Office of Research and Technology Public Roads magazine Office of Planning and Realty Office of Policy and Government Affairs Office of the Chief Financial Officer Office of Administration Office of Operations Office of Safety Office of Federal Lands Highway Office of Chief Counsel Office of Civil Rights Office of Public Affairs Long-Term Pavement Performance is a program supported by FHWA to collect and analyse road data.
The LTPP program was initiated by the Transportation Research Board of the National Research Council in the early 1980s. Federal Highway Administration with the cooperation of the American Association of State Highway and Transportation Officials sponsored the program; as a result of this program, FHWA has collected a huge database of road performance. FHWA and ASCE hold an annual contest known as LTPP International Data Analysis Contest, based on challenging researchers to answer a question based on the LTPP data. Current: Administrator: Brandye Hendrickson Deputy Administrator: Brandye Hendrickson Executive Director: Thomas Everett Alph Bartelsmeyer August 10, 1970- January 25, 1974 Alinda Burke - January 1, 1980 -? J. Richard Capka August 5, 2002 - May 31, 2006 Gregory G. Nadeau July 8, 2009 – July 30, 2014 Brandye Hendrickson July 24, 2017 - Present Federal Motor Carrier Safety Administration Hi
In the field of road transport, an interchange is a road junction that uses grade separation, one or more ramps, to permit traffic on at least one highway to pass through the junction without interruption from other crossing traffic streams. It differs from a standard intersection. Interchanges are always used when at least one road is a controlled-access highway or a limited-access divided highway, though they are sometimes used at junctions between surface streets. Note: The descriptions of interchanges apply to countries where vehicles drive on the right side of the road. For left-side driving, layout of the junctions is the only left/right is reversed. A freeway junction or highway interchange or motorway junction is a type of road junction linking one controlled-access highway to another, to other roads, or to a rest area or motorway service area. In the UK, most junctions are numbered sequentially. In the US, interchanges are either numbered by interchange number. A highway ramp or slip road is a short section of road that allows vehicles to enter or exit a controlled-access highway.
A directional ramp tends toward the desired direction of travel: A ramp that makes a left turn exits from the left side of the roadway. Left directional ramps are uncommon, as the left lane is reserved for high-speed through traffic. Ramps for a right turn are always right directional ramps. A non-directional ramp goes opposite to the desired direction of travel. Many loop ramps are non-directional. A semi-directional ramp exits in a direction opposite from the desired direction of travel turns toward the desired direction. Many flyover ramps are semi-directional. A U-turn ramp leaves the road in one direction, turns over or under it, rejoins in the opposite direction. Weaving is an undesirable situation where traffic veering right and left must cross paths within a limited distance, to merge with traffic on the through lane; the German Autobahn system has Autobahn-to-Autobahn interchanges of two types: a four-way interchange, the Autobahnkreuz, where two motorways cross. Some on-ramps have a ramp meter, a dedicated mid-ramp traffic light that controls the flow of entering vehicles.
A complete interchange has enough ramps to provide access from any direction of any road in the junction to any direction of any other road in the junction. A complete interchange between a freeway and another road requires at least four ramps. Complete interchanges between two freeways have at least eight ramps, as having fewer would reduce capacity and increase weaving. Using U-turns, the number for two freeways can be reduced to six, by making cars that want to turn left either pass by the other road first make a U-turn and turn right, or turn right first and make a U-turn. Depending on the interchange type and the connectivity offered other numbers of ramps may be used. For example, if a highway interchanges with a highway containing a collector/express system, additional ramps can be used to link the interchanging highway with the collector and express lanes respectively. For highways with high-occupancy vehicle lanes, ramps can be used to service these carriageways directly, thereby increasing the number of ramps used.
An incomplete interchange has at least one or more missing ramps that prevent access to at least one direction of another road in the junction from any other road in the junction. A cloverleaf interchange is a two-level, four-way interchange where all turns across opposing traffic are handled by non-directional loop ramps. Assuming right-handed traffic, to go left vehicles first cross over or under the target route bear right onto a curved ramp that turns 270 degrees, merging onto the target route from the right, crossing the route just departed; these loop ramps produce the namesake cloverleaf shape. Two major advantages of cloverleaves are that they require only one bridge which makes such junctions inexpensive as long as land is plentiful, that they do not require any traffic signals to operate. However, weaving is a major shortcoming of cloverleaves, as the four total offramps and onramps are present, merge on the main routes; the capacity of this design is comparatively low. Cloverleaves use a considerable area of land, are more found along older highways, in rural areas and within cities with low population densities.
A variant design separates all turning traffic into a parallel carriageway to minimize the problem of weaving. Collector and distributor roads are similar, but are separated from the main carriageway by a divider, such as a guard rail or Jersey barrier. A stack interchange is a four-way interchange whereby a semi-directional left turn and a directional right turn are both available. Access to both turns is provided by a single offramp. Assuming right-handed driving, in order to cross over incoming traffic and go left, vehicles first exit onto an off-ramp from the rightmost lane. After demerging from right-turning traffic, they complete their left turn by crossing both highways on a flyover ramp or underpass; the penultimate step is a merge with the right-turn on-ramp traffic from the opposite quadrant of the interchange. An onramp merges both streams o
State highways in California
The state highway system of the U. S. state of California is a network of highways that are owned and maintained by the Highway Division of the California Department of Transportation. Each highway is assigned a Route number in the Streets and Highways Code. Most of these are numbered in a statewide system, are known as State Route X. United States Numbered Highways are labeled US X, Interstate Highways are Interstate X. Under the code, the state assigns a unique Route X to each highway, does not differentiate between state, US, or Interstate highways; the California Highway Patrol is tasked with patrolling all state highways to enforce traffic laws. California's highway system is governed pursuant to Division 1 of the California Streets and Highways Code. Since July 1 of 1964, the majority of legislative route numbers, those defined in the Streets and Highways Code, match the sign route numbers. For example, Interstate 5 is listed as "Route 5" in the code. On the other hand, some short routes are instead signed as parts of other routes — for instance, Route 112 and Route 260 are signed as part of the longer State Route 61, Route 51 is part of Interstate 80 Business.
Concurrences are not explicitly codified in the Streets and Highways Code. The state may turn them over to local control. If the relinquished segment is in the middle of the highway's route, the local jurisdiction is required to install and maintain signs directing drivers to the continuation of that highway; the state may delete a highway and turn over an entire state route to local control. Business routes are not maintained by the state unless they are assigned legislative route numbers. A few routes or sections of routes are considered unrelinquished - a new alignment has been built, or the legislative definition has changed to omit the section, but the state still maintains the roadway — and are Route XU. There are two such unrelinqushed routes, with State Route 14U, an old alignment of State Route 14, as the most recent example of such, where the process to relinquish 14U started on January 1 of 2018, along with State Route 103U being the other unrelinquished route within the system; some new alignments are considered supplemental and have a suffix of S.
Both types of suffixed routes are considered spurs. Current or former unsigned suffixed routes include State Route 156U, signed as State Route 156 Business through Hollister, State Route 180S, the freeway replacement for State Route 180 in Fresno; the first legislative routes were defined by the State Highway Bond Act in 1909, passed by the California State Legislature and signed by Governor James Gillett. These, extensions to the system, were numbered sequentially. No signs were erected for these routes; the United States Numbered Highways were assigned by the American Association of State Highway Officials in November 1926, but posting did not begin in California until January 1928. These were assigned to some of the main legislative routes in California. Signs were posted by the Automobile Club of Southern California and California State Automobile Association, active in signing national auto trails and local roads since the mid-1900s. In 1934, after the major expansion of the state highway system in 1933 by the California Legislature, California sign route numbers were assigned by the California Division of Highways.
The California sign route numbers were assigned in a geographical system independent of the legislative routes. Odd-numbered routes ran north–south and even-numbered routes ran east–west; the routes were split among southern California and central and northern California as follows: 0 or 1 modulo 4: central and northern California 2 or 3 modulo 4: southern CaliforniaFor instance, State Route 1 and State Route 4 were in central and northern California, State Route 2 and State Route 3 were in southern California. A rough grid was used inside the two regions, with the largest numbers — all less than 200 - in eastern California and near the border between the two regions; the Interstate Highway System numbers were assigned by AASHO in late 1959. In 1963 and 1964, a total renumbering of the legislative routes was made, aligning them with the sign routes; some changes were made to the sign routes related to decommissionings of U. S. Routes in favor of Interstates. Since the 1990s, many non-freeway routes in urban areas, have been deleted and turned over to local control.
This transfers the cost of maintaining them from state to local budgets, but gives local governments direct control over urban arterial roads th
Mojave is a census-designated place in Kern County, United States. Mojave is located 50 miles east at an elevation of 2,762 feet; the town is located in the southwestern region of the Mojave Desert and east of Oak Creek Pass and the Tehachapi Mountains. The population was 4,238 at the 2010 census, up from 3,836 at the 2000 census. Telephone numbers in Mojave follow the format 824-xxxx and the area includes three postal ZIP Codes; the town of Mojave began in 1876 as a construction camp on the Southern Pacific Railroad. From 1884 to 1889, the town was the western terminus of the 165-mile, twenty-mule team borax wagon route originating at Harmony Borax Works in Death Valley, it served as headquarters for construction of the Los Angeles Aqueduct. Located near Edwards Air Force Base, Naval Air Weapons Station China Lake, Palmdale Regional Airport, Mojave has a rich aerospace history as well. Besides being a general-use public airport, Mojave has three main areas of activity: flight testing, space industry development, aircraft heavy maintenance and storage.
The closest airfield to the city known as the Mojave Airport, is now part of the Mojave Air and Space Port. In 1935, Kern County established the Mojave Airport 0.5 miles east of town to serve the gold and silver mining industry in the area. The airport consisted of two dirt runways, one of, oiled, but it lacked any fueling or servicing facilities. In 1941, the Civil Aeronautics Board began improvements to the airport for national defense purposes that included two 4,500 by 150 foot asphalt runways and adjacent taxiway. Kern County agreed. Following the Japanese attack on Pearl Harbor in December 1941, the U. S. Marine Corps took over the airport and expanded it into Marine Corps Auxiliary Air Station Mojave; the two existing runways were extended and a third one added. Barracks were constructed to house 2,734 376 female military personnel. Civilian employment at the base would peak at 176; the Marines would spend more than $7 million on the base, which totaled 2,312 acres. Many of the Corps' World War II aces received their gunnery training at Mojave.
During World War II, Mojave hosted 29 aircraft squadrons, four Carrier Aircraft Service Detachments, three Air Warning Squadrons. At its peak, the air station had other aircraft. Mojave had a 75 by 156 foot swimming pool, used to train aviators in emergency water egress and for recreation; the base's 900-seat auditorium hosted several USO shows that featured Bob Hope, Frances Langford and Marilyn Maxwell. With the end of WWII, MCAAS was dis-established on February 7, 1946. S. Navy Air Station was established the same day; the Navy used the airport for drone operations for less than a year, closing it on January 1, 1947. The base remained closed for four years until the outbreak of the Korean War. Mojave was reactivated as an auxiliary landing field to MCAS El Toro; the airport was recommissioned as a MCAAS on December 31, 1953. Squadrons used Mojave for ordnance training. Marine Corps reserve units were temporarily deployed to Mojave for two week periods. MCAAS Mojave personnel peaked at 200 civilians during this period.
In 1961, after the USMC transferred operations to MCAS El Centro, Kern County obtained title to the airport. In February 1972, the East Kern Airport District was formed to administer the airport. To a great extent EKAD was the brainchild of Dan Sabovich who lobbied the state for the airport district's creation and ran EKAD until 2002. During the 1970s, Mojave Airport was served by commuter air carrier Golden West Airlines with scheduled passenger flights operated with de Havilland Canada DHC-6 Twin Otter turboprops direct to Los Angeles. On November 20, 2012, the EKAD Board of Directors voted to change the name of the district to the Mojave Air and Space Port. Officials said that the spaceport name is well known around the world; the change took effect on January 1, 2013. The airport is now the home of various aerospace companies and institutions such as Scaled Composites and the civilian National Test Pilot School; the town was home to the Rutan Voyager, the first aircraft to fly around the world nonstop and unrefueled.
The airport is the first inland spaceport in the United States, was the location of the first private spaceflight, the launch of SpaceShipOne on June 21, 2004. Mojave has a Mojave Transportation Museum. Mojave is located at 35°03′09″N 118°10′26″W. According to the United States Census Bureau, the town has a total area of 58.4 square miles, over 99% of it land. Mojave has a desert climate (Köppen: BWk, cold desert for using an isotherm of mean annual temperature of less than 18 °C or hot desert for using an isotherm of less than 0 °C for the mean temperature of the coldest month, it has cool winters. Average January temperatures are a maximum of 57.8 °F and a minimum of 34.3 °F. Average July temperatures are a maximum of 97.7 °F and a minimum of 69.8 °F. There are an average of 98 days with highs of 90 °F and an average of 45.7 days with lows of 32 °F. The record high temperature was 118 °F on August 5, 1914; the record low temperature was 8 °F on December 23, 1990. Average annual rainfall is 5.96 inches.
There are an average of 22 days with measurable precipitation. The wettest year was 1983 with 15.51 inches and the driest year was 1942 with 0.85 inches. The most rainfall in one month
California is a state in the Pacific Region of the United States. With 39.6 million residents, California is the most populous U. S. the third-largest by area. The state capital is Sacramento; the Greater Los Angeles Area and the San Francisco Bay Area are the nation's second and fifth most populous urban regions, with 18.7 million and 9.7 million residents respectively. Los Angeles is California's most populous city, the country's second most populous, after New York City. California has the nation's most populous county, Los Angeles County, its largest county by area, San Bernardino County; the City and County of San Francisco is both the country's second-most densely populated major city after New York City and the fifth-most densely populated county, behind only four of the five New York City boroughs. California's $3.0 trillion economy is larger than that of any other state, larger than those of Texas and Florida combined, the largest sub-national economy in the world. If it were a country, California would be the 5th largest economy in the world, the 36th most populous as of 2017.
The Greater Los Angeles Area and the San Francisco Bay Area are the nation's second- and third-largest urban economies, after the New York metropolitan area. The San Francisco Bay Area PSA had the nation's highest GDP per capita in 2017 among large PSAs, is home to three of the world's ten largest companies by market capitalization and four of the world's ten richest people. California is considered a global trendsetter in popular culture, innovation and politics, it is considered the origin of the American film industry, the hippie counterculture, fast food, the Internet, the personal computer, among others. The San Francisco Bay Area and the Greater Los Angeles Area are seen as global centers of the technology and entertainment industries, respectively. California has a diverse economy: 58% of the state's economy is centered on finance, real estate services and professional, scientific and technical business services. Although it accounts for only 1.5% of the state's economy, California's agriculture industry has the highest output of any U.
S. state. California is bordered by Oregon to the north and Arizona to the east, the Mexican state of Baja California to the south; the state's diverse geography ranges from the Pacific Coast in the west to the Sierra Nevada mountain range in the east, from the redwood–Douglas fir forests in the northwest to the Mojave Desert in the southeast. The Central Valley, a major agricultural area, dominates the state's center. Although California is well-known for its warm Mediterranean climate, the large size of the state results in climates that vary from moist temperate rainforest in the north to arid desert in the interior, as well as snowy alpine in the mountains. Over time and wildfires have become more pervasive features. What is now California was first settled by various Native Californian tribes before being explored by a number of European expeditions during the 16th and 17th centuries; the Spanish Empire claimed it as part of Alta California in their New Spain colony. The area became a part of Mexico in 1821 following its successful war for independence but was ceded to the United States in 1848 after the Mexican–American War.
The western portion of Alta California was organized and admitted as the 31st state on September 9, 1850. The California Gold Rush starting in 1848 led to dramatic social and demographic changes, with large-scale emigration from the east and abroad with an accompanying economic boom; the word California referred to the Baja California Peninsula of Mexico. The name derived from the mythical island California in the fictional story of Queen Calafia, as recorded in a 1510 work The Adventures of Esplandián by Garci Rodríguez de Montalvo; this work was the fifth in a popular Spanish chivalric romance series that began with Amadis de Gaula. Queen Calafia's kingdom was said to be a remote land rich in gold and pearls, inhabited by beautiful black women who wore gold armor and lived like Amazons, as well as griffins and other strange beasts. In the fictional paradise, the ruler Queen Calafia fought alongside Muslims and her name may have been chosen to echo the title of a Muslim leader, the Caliph. It's possible.
Know ye that at the right hand of the Indies there is an island called California close to that part of the Terrestrial Paradise, inhabited by black women without a single man among them, they lived in the manner of Amazons. They were robust of body with great virtue; the island itself is one of the wildest in the world on account of the craggy rocks. Shortened forms of the state's name include CA, Cal. Calif. and US-CA. Settled by successive waves of arrivals during the last 10,000 years, California was one of the most culturally and linguistically diverse areas in pre-Columbian North America. Various estimates of the native population range from 100,000 to 300,000; the Indigenous peoples of California included more than 70 distinct groups of Native Americans, ranging from large, settled populations living on the coast to groups in the interior. California groups were diverse in their political organization with bands, villages, on the resource-rich coasts, large chiefdoms, such as the Chumash and Salinan.
Trade, intermarriage a
A concurrency in a road network is an instance of one physical roadway bearing two or more different route numbers. When two roadways share the same right-of-way, it is sometimes called commons. Other terminology for a concurrency includes overlap, duplex, multiplex, dual routing or triple routing. Concurrent numbering can become common in jurisdictions that allow it. Where multiple routes must pass between a single mountain crossing or over a bridge, or through a major city, it is economically and advantageous for them all to be accommodated on a single physical roadway. In some jurisdictions, concurrent numbering is avoided by posting only one route number on highway signs. Most concurrencies are a combination of two route numbers on the same physical roadway; this is practically advantageous as well as economically advantageous. Some countries allow for concurrencies to occur, others do not allow it to happen. In those nations which do permit concurrencies, it can become common. In these countries, there are a variety of concurrences.
An example of this is the concurrency of Interstate 70 and I-76 on the Pennsylvania Turnpike in western Pennsylvania. I-70 merges with the Pennsylvania Turnpike so the route number can continue east into Maryland. A triple Interstate concurrency is found in Wisconsin along the five-mile section of I-41, I-43, I-894 in Milwaukee, Wisconsin; the concurrency of I-41 and I-43 on this roadway is an example of a wrong-way concurrency. The longest Interstate highway concurrency is I-90 for 265 miles across Indiana and Ohio. There are examples of eight-way concurrencies: I-465 around Indianapolis and Georgia State Route 10 Loop around downtown Athens, Georgia. Portions of the 53-mile I-465 overlap with I-74, US Highway 31, US 36, US 40, US 52, US 421, State Road 37 and SR 67—a total of eight other routes. Seven of the eight other designations overlap between exits 46 and 47 to create an eight-way concurrency. In the United States, concurrencies are marked by placing signs for both routes on the same or adjacent posts.
The federal Manual on Uniform Traffic Control Devices prescribes that when mounting these adjacent signs together that the numbers will be arranged vertically or horizontally in order of precedence. The order to be used is Interstate Highways, U. S. Highways, state highways, county roads, within each class by increasing numerical value. Several states do not have any concurrencies, instead ending routes on each side of one. There are several circumstances. One example occurs along the Oklahoma–Arkansas state line. At the northern end of this border Oklahoma State Highway 20 runs concurrently with Arkansas Highway 43 and the two highways run north–south along the boundary. Concurrencies are found in Canada. British Columbia Highway 5 continues east for 12 kilometres concurrently with Highway 1 and Highway 97, through Kamloops; this stretch of road, which carries Highway 97 south and Highway 5 north on the same lanes, is the only wrong-way concurrency in British Columbia. In Ontario, the Queen Elizabeth Way and Highway 403 run concurrently between Burlington and Oakville, forming the province's only concurrency between two 400-series highways.
The concurrency was not in the original plan which intended for both the QEW and Highway 403 to run parallel to each other, as the Hamilton–Brantford and Mississauga sections of Highway 403 were planned to be linked up along the corridor now occupied by Highway 407. It was planned for the Mississauga section of Highway 403 would be renumbered as Highway 410 but this never came to pass. Highway 403 was signed concurrently along the Queen Elizabeth Way in 2002, remedying the discontinuity to avoid confusing drivers that wanted to travel between the two segments without using the toll Highway 407. Nonetheless, many surface street signs referring to that section of freeway with the QEW/Highway 403 concurrency still only use the highway's original designation of QEW, although the MTO has updated route markers on the QEW to reflect the concurrency. In the United Kingdom, routes do not run concurrently with others. Where this would occur, the roadway takes the number of only one of the routes, while the other routes are considered to have a gap and are signed in brackets.
An example is the meeting of the M60 and the M62 northwest of Manchester: the motorways coincide for the seven miles between junctions 12 and 18 but the motorway between those points is only designated as the M60. European route numbers as designated by UNECE may have concurrencies, but since the E-route numbers are unsigned and unused in the UK, the existence of these concurrencies is purely theoretical. In Sweden and Denmark, the most important highways use only the European route numbers that have cardinal directions. In Sweden the E6 and E20 run concurrently for 280 kilometres. In Denmark the E47 and E55 run concurrently for 157 kilometres. There are more shorter concurrencies. There are two stretches in Sweden