69-567: Interstate 270 ( I-270 ) is a 34.7-mile (55.8 km) auxiliary Interstate Highway in the U.S. state of Maryland that travels from I-495 (Capital Beltway) just north of Bethesda in Montgomery County north to I-70 in the city of Frederick in Frederick County . It consists of the 32.6-mile (52.5 km) mainline as well as a 2.1-mile (3.4 km) spur that provides access to and from southbound I-495. I-270
138-608: A loop route ) completely surrounds a metropolitan city, and it is often connected with multiple junctions to other routes. Unlike other auxiliary Interstate Highways (and by extension, all primary Interstate Highways ), beltways do not have termini; however, they have a place where the highway mileage resets to zero. Beltways are also preceded by an even number in the first digit. Some examples of beltways include: Single-point urban interchange A single-point urban interchange ( SPUI , / ˈ s p uː i / SPOO -ee or / ˈ s p juː i / SPEW -ee ), also called
207-412: 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 through limited amounts of space efficiently. A SPUI is similar in form to a diamond interchange but has the advantage of allowing opposing left turns to proceed simultaneously by compressing the two intersections of
276-418: A 10-lane freeway and merges with I-270 Spur, which provides access to and from southbound I-495. Past this interchange, I-270 continues north as a 12-lane freeway with an HOV lane and five travel lanes in each direction. The route passes through wooded suburban areas, where, prior to the cloverleaf interchange with Montrose Road (unsigned MD 927 ), I-270 takes on a local–express lane configuration with
345-475: A HOV lane for carpools with two or more people that is in operation between 3:30 and 6:30 pm on weekdays in the northbound direction and between 6:00 and 9:00 am on weekdays in the southbound direction. I-270 Spur continues north through wooded suburban areas to an interchange with Democracy Boulevard adjacent to the Westfield Montgomery shopping mall. A short distance later, the road has
414-545: A SPUI allows only left and right turns, drivers may not reenter the freeway they are departing (if, for example, they realize that they have taken the wrong exit) within a SPUI. Three-phase traffic signals are required. Other interchange types designed for efficiency, such as the six-ramp partial cloverleaf and the diverging diamond , require just two signal phases. The first SPUI opened on February 25, 1974, along U.S. Route 19 ( State Road 55 ), which goes over State Road 60 east of Clearwater, Florida . It
483-458: A SPUI. A freeway-over SPUI (as in the lower photo) requires a longer bridge of the free-flowing road to cross the wider area required for the SPUI intersection below. Because vehicles must be able to cross the pavement in six different ways, a SPUI generally has a very large area of uncontrolled pavement in the middle of the intersection. This can be unsafe particularly if drivers are unfamiliar with
552-536: A continuous green T-intersection with the bridges. The ramps cross each other at-grade , with a traffic light -controlled intersection. An interchange, like that in Millvale, Pennsylvania, formerly existed at the junction of SR 7 and SR 822 at the now-demolished Fort Steuben Bridge in Steubenville, Ohio . The northbound carriageway of SR 7 passed under the bridge, with lefthand ramps meeting
621-404: A diamond into one single intersection over or under the free-flowing road. The term "single-point" refers to the fact that all through traffic on the arterial street, as well as the traffic turning left onto or off the interchange, can be controlled from a single set of traffic signals . Due to the space efficiency of SPUIs relative to the volume of traffic they can handle, the interchange design
690-750: A freeway running through residential areas. The NCPC agreed, and it approved the western route two years later. Further details about the routing were released in 1949, and construction began with the northern section in February 1950. On January 25, 1953, the US ;240 freeway was completed between Frederick to Urbana. The freeway's extension to Hyattstown opened on June 10, 1953. The extension to MD 118 in Germantown opened September 15, 1954. A group of people opposed any highway in Rockville because of
759-496: A groundbreaking ceremony. The project was completed on June 11, 2020, a month ahead of schedule. MDSHA is studying improvements for the I-270 corridor between Shady Grove Road and Frederick. Options for improvement include widening the highway to include more lanes with HOV and HOT lanes, as well as initiating rapid bus or light rail service along I-270 between Shady Grove and Clarksburg. In September 2017, Governor Larry Hogan announced
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#1732782362986828-595: A northbound HOV lane. I-270 continues into the Germantown area and interchanges with MD 118 (Germantown Road). A short distance later, after passing by some business parks, I-270 comes to an interchange with MD 27 (Ridge Road) and Father Hurley Boulevard. Past MD 27, I-270 heads into more rural areas of woods with some farm fields, paralleled by a set of power lines . The road has an interchange with MD 121 (Clarksburg Road) in Clarksburg near
897-689: A plan to widen the entire length of I-270 by four lanes, adding HOT lanes to the median, as part of a $ 9-billion proposal to widen roads in Maryland. The project would be a public–private partnership with private companies responsible for constructing, operating, and maintaining the lanes. On June 5, 2019, the Maryland Board of Public Works voted 2–1 in favor of the proposal to construct express toll lanes along I-270, with Governor Hogan and State Comptroller Peter Franchot voting for it and State Treasurer Nancy Kopp voting against it. On June 12, 2019,
966-430: A significant difference between the two types of interchanges in terms of total collisions, the injury and fatality rates are notably lower for SPUIs than diamond interchanges. The major disadvantage of SPUIs over other types of road junctions is the increased cost due to the need for a longer or wider bridge. A freeway-under SPUI (as in the upper diagram) requires a wider bridge over the free-flowing road to make room for
1035-623: A single signal, vehicles can clear the intersection much more quickly than in a diamond interchange (which requires two sets of traffic signals). SPUIs also allow for wider turns, easing movement for large vehicles, such as trucks and RVs. Furthermore, a SPUI takes up considerably less space than a full cloverleaf interchange , allowing construction to take place on a limited amount of property and minimizing state use of eminent domain . Finally, SPUIs are reportedly safer than other space-efficient interchange forms, such as (standard) diamond interchanges. Research suggests that, although there may not be
1104-521: A six-lane freeway . The left lane on each side is used as an HOV lane for carpools with two or more people in the northbound direction between 3:30 and 6:30 pm on weekdays and in the southbound direction between 6:00 and 9:00 am on weekdays. At the southern terminus, I-270 only has access to and from the eastbound direction of I-495. The road turns west and comes to an interchange with MD 187 (Old Georgetown Road) and Rockledge Drive (unsigned MD 187B ). From there, I-270 continues west as
1173-414: A snowplow leave piles of snow, interfering with traffic and visibility in the middle of the uncontrolled pavement. Additionally, if the wide area of uncontrolled pavement is on a bridge, as in the diagram, the snow cannot be pushed to the sides of the bridge as it may pose a hazard to the road underneath. This problem can be exacerbated by the comparatively large bridge width required by the SPUI. Given that
1242-572: A southbound exit and northbound entrance for the HOV lanes onto Fernwood Road. Past here, I-270 Spur merges into northbound I-270 with separate ramps for the travel lanes and the HOV lanes. Before 1975, when I-270 was called I-70S, this road was called I-270, without the word "Spur". The entire route is in Bethesda , Montgomery County . Auxiliary Interstate Highway Auxiliary Interstate Highways (also called three-digit Interstate Highways ) are
1311-492: A subset of highways within the United States' Interstate Highway System . The 323 auxiliary routes generally fall into three types: spur routes , which connect to or intersect the parent route at one end; bypasses , which connect to the parent route at both ends; and beltways , which form a circle that intersects the parent route at two locations. Some routes connect to the parent route at one end but to another route at
1380-423: A surface intersection. The most commonly cited advantages of SPUIs are improved operation efficiency and safety as well as reduced right-of-way requirements compared to other interchange forms. Left-turning traffic from both directions of the intersecting roadways is able to turn simultaneously without crossing the path of the opposing left turns. Because traffic passing through the interchange can be controlled by
1449-446: A typical 3-digit Interstate Highway, bypasses usually have both its two termini junctioned with another Interstate highway. Bypass routes are preceded by an even number in the first digit. Examples include: In the case of an auxiliary Interstate highway which has both ends at Interstates but not the same Interstate, some states treat these as bypasses while others treat these as spurs—see Spur route above. A beltway (also known as
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#17327823629861518-897: Is also a SPUI on the Frankenschnellweg , the urban part of the A73 , and Maximilianstraße, in Nuremberg (at 49°27′06″N 11°02′17″E / 49.451708°N 11.038102°E / 49.451708; 11.038102 ). Smaller versions of the SPUI can also be found on non-autobahn roads in German cities, with right-turning traffic under signal control, located in Heilbronn , Karlsruhe , Sindelfingen , Stuttgart , and Wiesbaden . SPUIs are also found in Australia, Canada, Hong Kong, Indonesia, and Singapore. A rarely built variant of
1587-433: Is expected unless fairly substantial changes to the design or special accommodations are provided. Pedestrians are usually not able to get through the intersection with one green light. It can take up to four cycles to walk through the entire length of a SPUI. Finally, SPUIs can be somewhat difficult to clear of snow. The large area in which lanes cross may have to be shut down to allow efficient and thorough cleaning lest
1656-696: Is known as the Washington National Pike , and makes up the easternmost stretch of the Dwight D. Eisenhower Highway . Most of the southern part of the route in Montgomery County passes through suburban areas around Rockville and Gaithersburg that are home to many biotech firms. This portion of I-270 is up to 12 lanes wide and consists of a local–express lane configuration as well as high-occupancy vehicle lanes (HOV lanes) that are in operation during peak travel times. North of
1725-419: Is used extensively in the reconstruction of existing freeways as well as constructing new freeways, particularly in dense urban environments. Sometimes a SPUI will allow traffic to proceed straight through from the offramp to the onramp; this usually happens when the ramps connect with frontage roads . Since most through traffic travels over or under the intersection, the SPUI is still much more efficient than
1794-423: Is usually one of the following: Examples include: Sometimes, a three-digit Interstate Highway branches off from another three-digit Interstate Highway. These spurs do not connect directly with their parent highways, but are associated with them via the three-digit highways they do intersect with. Examples include: A bypass route may traverse around a city, or may run through it with the mainline bypassing. In
1863-593: The Maryland-National Capital Park and Planning Commission (M-NCPPC) sent a letter of nonconcurrence to MDSHA, triggering a mediation process with MDSHA. The M-NCPPC has jurisdiction over parkland MDSHA will need for its proposal. In June 2021, the project was omitted by the Washington Council of Government's Transportation Planning Board, calling its future into question. In June 2022 Montgomery County Executive Marc Elrich asked
1932-713: The North Central Freeway to connect directly to I-95 . Plans for this freeway initially began in 1959 when a freeway was called for along the Georgia Avenue corridor. In the mid-1960s, a study was proposed for the freeway that recommended several different routings between Washington, D.C., and the Capital Beltway. By 1966, a route for the North Central Freeway was planned along a Baltimore and Ohio Railroad line running through
2001-510: The Town Center at Aurora shopping center in Aurora, Colorado , United States (at 39°42′40″N 104°49′33″W / 39.711189°N 104.825807°W / 39.711189; -104.825807 ). A three-level SPUI is similar to a standard SPUI but includes an additional grade separation allowing for free-flowing through traffic on the crossroad; such through traffic thus bypasses
2070-405: The U.S. Department of Transportation (USDOT) to extend its review period for the I-270 toll lane proposal, citing the need for additional time for local agencies and the public to review the environmental analysis. In July 2022 advocates of public transit questioned the validity of Maryland DOT's traffic models for the proposed highway widening project, in a letter submitted to USDOT. In August 2022
2139-472: The "side road" at this interchange. The southbound carriageway of SR 7 bridges over the interchange, while its northbound carriageway remains at-grade. SR 7's left on- and offramps run between its carriageways, meeting the I-470 ramps at an at-grade intersection. The I-470 ramps proceed to a trumpet interchange with I-470. I-470 itself bridges over both carriageways of SR 7 a short distance north of
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2208-589: The Clarksburg Premium Outlets, and the northbound HOV restriction ends past this interchange, with I-270 continuing north as a four-lane freeway. The power lines stop paralleling the route, and it continues through more rural areas of woods and farms, running closely parallel to MD 355. The median widens, with trees in the middle, and I-270 has weigh stations on both sides. The highway reaches Hyattstown , where it has an interchange with MD 109 (Old Hundred Road). A short distance past
2277-584: The FHWA announced a delay in its review of the proposed project. In August 2023, Maryland DOT applied for a federal grant to support improvements on the American Legion Bridge and a portion of I-495 leading to the junction with I-270. The application did not include funding for improvements to I-270, but the state intends to include I-270 improvements in future grant applications. Interstate 270 Spur ( I-270 Spur ; referred to as I-270Y by
2346-637: The Gaithersburg area, the road continues through the northern part of Montgomery County, passing Germantown and Clarksburg as a six- to eight-lane highway with an HOV lane in the northbound direction only. North of here, I-270 continues through rural areas into Frederick County and toward the city of Frederick as a four-lane freeway. The freeway was built between 1953 and 1960 as the Washington National Pike between Bethesda and Frederick and carried U.S. Route 240 (US 240), which
2415-408: The I-270 corridor as far north as Germantown and increased traffic counts along the road. Much of I-270 in Montgomery County is now a hub for biotech firms. By 1999, congestion on the road grew to then-projected 2010 levels. In Montgomery County, an interchange was constructed to allow northbound and southbound I-270 access both to and from Watkins Mill Road in Gaithersburg. This interchange connects
2484-618: The I-470/SR ;7 ramps' intersection. This design was likely chosen not for cost savings but because the northbound carriageway of SR 7 is bordered by railroad tracks, commercial properties, and the Ohio River and because I-470 bridges the river just east of SR 7—a more conventional interchange design was likely more difficult to achieve. There is another such interchange in Millvale, Pennsylvania , near Pittsburgh , at
2553-525: The MD ;109 interchange, I-270 crosses into Frederick County , continuing northwest through rural woodland and farmland. It reaches the Urbana area, where the route has an interchange with MD 80 (Fingerboard Road). The highway briefly runs along the east side of MD 80 past this interchange before continuing through agricultural areas. It features a scenic overlook in the northbound direction as
2622-453: The MDSHA) is a 2.1-mile (3.4 km) spur off I-270 that connects I-270 and the Capital Beltway. It carries traffic headed southbound on I-270 to southbound I-495 and from northbound I-495 to northbound I-270, filling in the missing movements not available at the interchange between I-270 and I-495. The road heads north from I-495 as a six-lane freeway. The left lane in each direction serves as
2691-433: The SPUI is the inverted SPUI , in which the carriageways of the free-flowing road are separated, with left on- and offramps running between the carriageways and coming to a single at-grade intersection with the cross street. This can be built less expensively than a standard SPUI by allowing for shorter, simpler bridges at the interchange. However, this inverts the usual convention of placing carriageway on- and offramps on
2760-669: The Takoma Park, Brookland , and Michigan Park neighborhoods who were successful in getting the freeway canceled through their neighborhoods in 1970. The North Central Freeway within Maryland was canceled by the Maryland State Highway Administration (MDSHA) in 1972 due to opposition from officials in Montgomery County. In 1975, the Federal Highway Administration (FHWA) officially approved withdrawal of plans to construct
2829-422: The bridge approach, while the southbound carriageway had a continuous green T-intersection with the bridge. An offset SPUI is similar to a diamond interchange, however, by making two of the ramps flyovers or flyunders , all ramps are pushed to one side of the highway, where they meet the surface street at a single intersection. An example of this is the interchange between Interstate 225 and Alameda Avenue near
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2898-475: The compressed on- and offramps. However, this disadvantage poses less of a problem in cases where the arterial, or nonfreeway road, already requires a very wide bridge. The intersection of 97 Street , having seven throughlanes, with Yellowhead Trail in Edmonton , Alberta, Canada, though a diamond interchange in concept, required such a wide bridge that traffic-signal phasing allows this intersection to behave as
2967-566: The corridor between Washington, D.C. , and Frederick, with several federal agencies including the United States Atomic Energy Commission and the National Bureau of Standards moving their headquarters to Montgomery County. A western spur that provided access to southbound I-495 was eventually built and became I-270. I-70S was projected to continue past the Capital Beltway into Washington, D.C., on
3036-697: The eastern and western portions of Watkins Mill Road by a new overpass. In addition, a new southbound exit ramp at exit 11 (MD 124) was built. The exit provides better access to the Metropolitan Grove station and Gaithersburg Medical Center. The goal of the project was to lower congestion on I-270, MD 355, and MD 124. The State of Maryland approved the $ 99.71-million (equivalent to $ 122 million in 2023) project in July 2017, and construction began on July 11, 2017, with Governor Larry Hogan and County Executive Ike Leggett in attendance for
3105-593: The free-flowing road is at-grade with but still separated from the side road, as found in a continuous green T- (or seagull) intersection . There is one such interchange in Pultney Township, Belmont County, Ohio , between State Route 7 (SR 7) and Interstate 470 (I-470) at 40°02′52″N 80°44′01″W / 40.047657°N 80.733542°W / 40.047657; -80.733542 . The ramps leading to and from I-470 run west of, but are not directly connected to, SR 7; these ramps form
3174-556: The freeway continues north as the Frederick Freeway, a part of US 40 that interchanges with US 15 and US 340 a short distance north of I-270’s northern terminus. On November 20, 1944, the National Capital Park and Planning Commission (NCPC) announced plans to build a freeway through Montgomery County. The freeway would bypass Bethesda, Rockville, and Gaithersburg. Under one proposed route,
3243-563: The freeway passes numerous business parks and some wooded areas before coming to an interchange with Shady Grove Road. Past this interchange, I-270 leaves Rockville and heads into Gaithersburg , where it intersects I-370 . This highway provides access to a park and ride lot at the Shady Grove station , which serves Washington Metro 's Red Line , and MD 200 (Intercounty Connector), which heads east to I-95 in Laurel . Past I-370,
3312-525: The freeway would end at US 240 (present-day MD 355) north of Gaithersburg, while another proposal had the freeway continuing to Hagerstown. South of Bethesda, one proposal had the freeway connecting with Macarthur Boulevard in the District of Columbia , while another proposal had the freeway going around Cabin John and connect with Macarthur Boulevard in Maryland. Bethesda residents objected to idea of
3381-562: The freeway's path. The concurrent US 240 designation was removed in 1972 and I-70S became I-270 in 1975. Increasing traffic levels led to a $ 200-million (equivalent to $ 496 million in 2023) widening of the road in Montgomery County to its current configuration. Many improvements are slated for I-270, including the widening of the route that would add high-occupancy toll lanes (HOT lanes). I-270 heads northwest from an interchange with I-495 (Capital Beltway) and MD 355 (Rockville Pike) in suburban Bethesda , Montgomery County , as
3450-462: The interchange type. Drivers making a left turn may become confused as oncoming turning traffic passes them on the righthand side. Due to the large intersection area, the traffic lights need a longer yellow and red phase to clear the intersection, and, even then, it may not be long enough for a bicyclist entering on green or yellow to make it across before opposing traffic gets a green. In general, SPUI designs should not be used where bicycle traffic
3519-494: The junction between Pennsylvania Route 28 (PA 28) and the 40th Street Bridge . The northbound carriageway of PA 28 passes under the interchange, with lefthand ramps meeting at the bridge (the northbound entrance ramp does not provide direct access to PA 28). The southbound carriageway of PA 28 has a continuous green T-intersection with the bridge. A similar interchange exists in Coal Grove, Ohio , at
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#17327823629863588-587: The junction of U.S. Route 52 (US 52) with the Ben Williamson Memorial Bridge and the Simeon Willis Memorial Bridge , which cross the Ohio River and lead to and from Ashland, Kentucky , respectively. The eastbound carriageway of US 52 passes under the interchange, with lefthand exit and entrance ramps to the bridges. The westbound carriageway of US 52, which narrows to one throughlane, has
3657-465: The local lane configuration ends in the southbound direction, which now has an HOV lane and four travel lanes while the northbound direction still has an HOV lane, three express lanes, and two local lanes. I-270 continues past more suburban development before coming to a northbound exit and southbound entrance with MD 117 (West Diamond Avenue). Past this interchange, the southbound HOV restrictions end and I-270 continues north with four travel lanes in
3726-507: The northeastern part of Washington and Takoma Park north to the Capital Beltway. In a 1971 study by DeLeuw, Cather Associates and Harry Wesse & Associates, LTD, I-70S was planned to run from its southern terminus at I-495 and run concurrent with that route before turning south on the North Central Freeway and ending at I-95 in Washington. The routing of the freeway through residential areas of Washington drew opposition from residents of
3795-433: The numbers can repeat from state to state along their route, but they will not repeat within a state. There are three states that have no auxiliary Interstate Highways: Alaska, Arizona, and New Mexico. North Dakota has an auxiliary route, but it is unsigned , and Wyoming's does not meet Interstate Highway standards. Auxiliary Interstates are divided into three types: spur , loop , and bypass routes. The first digit of
3864-687: The other end; some states treat these as spurs while others treat them as bypasses. Like the primary Interstate Highways , auxiliary highways meet Interstate Highway standards (with rare exceptions ). The shorter auxiliary routes branch from primary routes; their numbers are based on the parent route's number. All of the supplement routes for Interstate 95 (I-95) are designated with a three-digit number ending in "95": I-x95. With some exceptions, spur routes are numbered with an odd hundreds digit (such as I-395 ), while bypasses and beltways are numbered with an even hundreds digit (such as I-695 ). Because longer Interstates may have many such supplemental routes,
3933-505: The outer two lanes serving as local lanes and the inner three lanes and the HOV lane serving as express lanes. Past Montrose Road, I-270 continues north into the Rockville area, turning northwest before it comes to a single-point urban interchange with MD 189 (Falls Road), where the highway sees 253,620 vehicles daily. The road continues to a modified cloverleaf interchange with MD 28 (Montgomery Avenue). Past MD 28,
4002-414: The perceived increase in traffic, and the group had threatened to form a human chain in the middle of the freeway, but they did not carry through with their threat. The freeway's extension to MD 28 in Rockville opened on May 18, 1956. The Maryland State Roads Commission determined that a portion of Monroe Street in Rockville should be closed in order to avoid building a costly overpass to continue
4071-408: The right side of the carriageway, instead placing them on the left side, usually considered the passing lane . There is also a variant of the inverted SPUI, which can be used when a side road ends at, rather than crossing, a free-flowing road. In this variant, one carriageway of the free-flowing road is grade-separated from the side road, as with a typical inverted SPUI, while the other carriageway of
4140-622: The road passes through Monocacy National Battlefield , which was the site of the Battle of Monocacy . I-270 eventually leaves the battlefield area and continues into the commercial outskirts of Frederick . Here, the road reaches an interchange with MD 85 (Buckeystown Pike) near the Francis Scott Key Mall . I-270 continues through commercial areas before coming to its northern terminus at an interchange with I-70 and US 40 (Baltimore National Pike). Past this interchange,
4209-538: The road south of the Capital Beltway. Similar opposition also affected I-70N's eastward extension into Baltimore proper, although a small part of its planned spur, I-170 (now US 40, as the freeway never connected to any other Interstate), was built and opened in 1979. I-70 was eventually truncated to I-695 (the Baltimore Beltway) in 2014, with the freeway to its former terminus designated, but unsigned, as MD 570 . The concurrent US 240 designation
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#17327823629864278-403: The road to the west side of the new freeway. The Montgomery County Council had opposed the idea, but it ultimately withdrew its opposition because the federal government had agreed to add and pay for a freeway interchange with Montrose Road, which had not been in the freeway's original plan. In 1956, the US 240 freeway was completed from US 15 north to US 40. The US 240 freeway
4347-640: The southbound direction and an HOV lane, three express lanes, and two local lanes in the northbound direction before reaching MD 124 (Quince Orchard Road). Past MD 124, the northbound local lanes continue to the diamond interchange at Watkins Mill Road, after which they end. From there, I-270 heads northwest as an eight-lane freeway with four southbound lanes, an HOV lane, and three travel lanes northbound. It passes through wooded areas, leaving Gaithersburg and comes to an interchange with Middlebrook Road. The freeway narrows to six lanes again past at this interchange, with three lanes in each direction, including
4416-422: The standard numbering guidelines exist for a number of reasons. In some cases, original routes were changed, extended, or abandoned, leaving discrepancies in the system. In other cases, it may not be possible to use the proper number because the limited set of available numbers has been exhausted, causing a "non-standard" number to be used. A spur route 's number usually has an odd number for its first digit. It
4485-521: The three digits usually signifies whether a route is a bypass, spur, or beltway. The last two digits are derived from the main Interstate Highway. For instance, I-115 contains an odd number in the first digit (1), which indicates that this freeway is a spur. The last two digits signify the highway's origin. In this case, the "15" in I-115 shows that it is a supplement to I-15 . Exceptions to
4554-532: Was designed by Wallace Hawkes, Director of Transportation Engineering at J. E. Greiner Company (later URS Corporation ), who has been called the "granddaddy of the urban interchange". This design has since been altered to include frontage roads in each direction. Several SPUIs, built in the 1970s and later, are located on German autobahns, like the A40 , A42 , A44 , A46 , A57 , A59 , and A113 in Berlin . There
4623-492: Was extended south to Montrose Road in December 1957. I-70S was designated onto the US 240 freeway in 1959, while I-70N was designated onto the US 40 freeway to Baltimore. On December 17, 1958, the freeway extension to Old Georgetown Road opened. With the completion of the freeway, the original US 240 was newly designated MD 355. The construction of the Washington National Pike resulted in suburban growth along
4692-603: Was removed from I-70S in 1972. On May 18, 1975, I-70S was designated I-270, with I-70N becoming simply I-70. The western spur is now signed and publicly known simply as I-270 Spur. By the 1980s, traffic congestion had grown on I-270 in Montgomery County; as a result, a $ 200-million (equivalent to $ 496 million in 2023) project widened the road between I-495 and MD 118 to its current configuration since October 12, 1990, with some portions being widened from 6 to 12 lanes. HOV lanes were later added on December 19, 1996. This widening led to growth of residences and businesses along
4761-556: Was rerouted off what is now Maryland Route 355 (MD 355) between these two points. With the creation of the Interstate Highway System a few years later, the road was designated as I-70S along with US 240. There were plans to extend I-70S to I-95 in Washington, D.C. , on the North Central Freeway from the Capital Beltway; however, they were canceled in the 1970s due to opposition from residents in
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