Parts of this article (those related to track examples) need to be updated.(January 2015) |
Rail speed limits in the United States are regulated by the Federal Railroad Administration. Railroads also implement their own limits and enforce speed limits. Speed restrictions are based on a number of factors including curvature, signaling, track condition, and the presence of grade crossings. Like road speed limits in the United States, speed limits for tracks and trains are measured in miles per hour (mph).
This section needs expansionwith: any history from before 1980s. You can help by adding to it. (January 2011) |
Federal regulators set train speed limits based on the signaling systems in use. [1] Passenger trains were limited to 59 mph (95 km/h) and freight trains to 49 mph (79 km/h) on tracks without block signals, known as "dark territory." Trains without an automatic cab signal, train stop, or train control system were not allowed to exceed 79 mph (127 km/h). This rule, issued in 1947 and effective by the end of 1951, was a response to a serious 1946 crash in Naperville, Illinois, involving two trains. [2] [3] [4]
Following a 1987 train collision in Maryland, freight trains in high-speed areas were required to have speed limiters that could forcibly slow trains, rather than just alerting the operator through in-cab signals. In the Maryland crash, the signal panel had been partially disabled, including a muted whistle and a missing light bulb.
In response to the 2008 Chatsworth train collision in California, a federal law required that positive train control (PTC) be implemented nationwide by 2015. [5] After several extensions, the Federal Railroad Administration (FRA) announced on December 29, 2020, that PTC was operating on all required freight and passenger rail routes. [6] While PTC’s main purpose is to prevent collisions, it also allows higher speeds in some cases. Different PTC systems are used in various regions across the country.
This section needs expansion. You can help by adding to it. (January 2011) |
In the United States, the Federal Railroad Administration has developed a system of classification for track quality. [7] [8] The class of a section of track determines the maximum possible running speed limits and the ability to run passenger trains.
Track type | Freight train | Passenger | Examples |
---|---|---|---|
Excepted [us 1] | <10 mph (16 km/h) | not allowed | |
Class 1 | 10 mph (16 km/h) | 15 mph (24 km/h) | Much yard, branch line, short line, and industrial spur trackage falls into this category. |
Class 2 | 25 mph (40 km/h) | 30 mph (48 km/h) | Branch lines, secondary main lines, many regional railroads, and some tourist operations frequently fall into this class. Examples include the Burlington Northern Santa Fe (BNSF) branch from Sioux Falls to Madison, South Dakota; Napa Valley Wine Train’s 18-mile (29 km) ex-Southern Pacific Railroad line between Napa and St. Helena, California; and the entire Strasburg Rail Road, spanning 4+1⁄2 miles (7.2 km) between Strasburg and Leaman Place, Pennsylvania. [9] |
Class 3 | 40 mph (64 km/h) | 60 mph (97 km/h) | BNSF between Spokane and Kettle Falls, Washington; and Canadian National’s Wisconsin Central line between Neenah, Wisconsin and Sault Ste. Marie, Michigan. [9] |
Class 4 [us 2] | 60 mph (97 km/h) | 80 mph (129 km/h) | Chicago’s Metra; and New England Central’s entire main line. [9] |
Class 5 [us 3] | 80 mph (129 km/h) | 90 mph (145 km/h) | Union Pacific's (UP's) Geneva, Clinton, and Boone subdivisions in Iowa between East Missouri Valley (near Council Bluffs) to the Illinois border near Clinton; [10] UP’s main line between Council Bluffs and North Platte, Nebraska; Amtrak/SCRRA's and NCTD's Surf Line between Fullerton and San Diego, California. [9] |
Class 6 | 110 mph (177 km/h) | Parts of Amtrak’s Hartford Line between New Haven, Connecticut and Springfield, Massachusetts; [11] most of Amtrak's Lincoln Service between Chicago, Illinois and St. Louis, Missouri; [12] portions of Amtrak's Wolverine between Chicago and Pontiac, Michigan; and Brightline between West Palm Beach and Cocoa, Florida. [13] | |
Class 7 [us 4] | 125 mph (201 km/h) | Most of Amtrak's Northeast Corridor; [14] and Brightline between Orlando International Airport and Cocoa, FL. [13] | |
Class 8 [us 5] | 160 mph (257 km/h) | Texas Central Railway; 3 segments of the Northeast Corridor totaling 33.9 mi (54.6 km) in Rhode Island/Massachusetts [14] and an additional 16 mi (26 km) in New Jersey; Brightline West will have Class 8 trackage on its 218 mi (351 km) route between Rancho Cucamonga, California and Las Vegas, Nevada, going at top speeds of 186 mph (299 km/h). | |
Class 9 [us 6] | 220 mph (354 km/h) | California High-Speed Rail between Merced and Bakersfield. |
Assuming a suitably maintained track, maximum track speed through curves is limited by the "centrifugal force" which acts to overturn the train. To compensate for this force, the track is superelevated (the outer rail is raised higher than the inner rail). The speed at which the centrifugal force is perfectly offset by the tilt of the track is known as the balancing speed. Maximum speed can be found using the following formula, which provides an allowance for trains to operate above the balancing speed:
where:
Normally, passenger trains run above the balancing speed, and the difference between the balancing superelevation for the speed and curvature and the actual superelevation on the curve is known as unbalanced superelevation. Track superelevation is usually limited to 6 inches (150 mm), and is often lower on routes with slow heavy freight trains in order to reduce wear on the inner rail. Allowed unbalanced superelevation in the U.S. is restricted to 3 inches (76 mm), though 6 inches (152 mm) is permissible by waiver. Tilting trains like the Acela operate with even higher unbalanced superelevation, by dynamically shifting the weight of the train. The actual overturning speed of a train is much higher than the limits set by the speed formula, which is largely in place for passenger comfort. There is no hard maximum unbalanced superelevation for European railways, some of which have curves with over 11 inches (280 mm) of unbalanced superelevation to permit high-speed transportation. [15]
The allowed unbalanced superelevation will cause trains to run with normal flange contact. The points of wheel-rail contact are influenced by the tire profile of the wheels. Allowance has to be made for the different speeds of trains. Slower trains will tend to make flange contact with the inner rail on curves, while faster trains will tend to ride outwards and make contact with the outer rail. Either contact causes wear and tear and may lead to derailment if speeds and superelevation are not within the permitted limits. Many high-speed lines do not permit the use of slower freight trains, particularly with heavier axle loads. In some cases, the wear or friction of flange contact on curves is reduced by the use of flange lubrication.
The Acela is Amtrak's flagship passenger train service along the Northeast Corridor (NEC) in the Northeastern United States between Washington, D.C. and Boston via 13 intermediate stops, including Baltimore, New York City and Philadelphia. Acela trains are the fastest in the Americas, reaching 150 miles per hour (240 km/h), but only over 49.9 miles (80.3 km) of the 457-mile (735 km) route.
The Northeast Corridor (NEC) is an electrified railroad line in the Northeast megalopolis of the United States. Owned primarily by Amtrak, it runs from Boston in the north to Washington, D.C., in the south, with major stops in Providence, New Haven, Stamford, New York City, Newark, Trenton, Philadelphia, Wilmington, and Baltimore. The NEC is roughly paralleled by Interstate 95 for most of its length. Carrying more than 2,200 trains a day, it is the busiest passenger rail line in the United States by ridership and service frequency.
In rail transport, a derailment is a type of train wreck that occurs when a rail vehicle such as a train comes off its rails. Although many derailments are minor, all result in temporary disruption of the proper operation of the railway system and they are a potentially serious hazard.
The Keystone Corridor is a 349-mile (562 km) railroad corridor between Philadelphia and Pittsburgh, Pennsylvania, that consists of two rail lines: Amtrak and SEPTA's Philadelphia-to-Harrisburg main line, which hosts SEPTA's Paoli/Thorndale Line commuter rail service, and Amtrak's Keystone Service and Pennsylvanian inter-city trains; and the Norfolk Southern Pittsburgh Line. The corridor was originally the Main Line of the Pennsylvania Railroad.
On January 4, 1987, two trains collided on Amtrak's Northeast Corridor main line near Chase, Maryland, United States, at Gunpow Interlocking. Amtrak train 94, the Colonial, traveling north from Washington, D.C., to Boston, crashed at over 100 miles per hour (160 km/h) into a set of Conrail locomotives running light which had fouled the mainline. Fourteen passengers on the Amtrak train died, as well as the Amtrak engineer and lounge car attendant.
The Lackawanna Cut-Off was a rail line built by the Delaware, Lackawanna and Western Railroad (DL&W). Constructed from 1908 to 1911, the line was part of a 396-mile (637 km) main line between Hoboken, New Jersey, and Buffalo, New York. It ran west for 28.45 miles (45.79 km) from Port Morris Junction in Port Morris, New Jersey, near the south end of Lake Hopatcong about 45 miles (72 km) west-northwest of New York City, to Slateford Junction in Slateford, Pennsylvania near the Delaware Water Gap.
Plans for high-speed rail in the United States date back to the High-Speed Ground Transportation Act of 1965. Various state and federal proposals have followed. Despite being one of the world's first countries to get high-speed trains, it failed to spread. Definitions of what constitutes high-speed rail vary, including a range of speeds over 110 mph (180 km/h) and dedicated rail lines. Inter-city rail with top speeds between 90 and 125 mph is sometimes referred to in the United States as higher-speed rail.
The Wolverine is a higher-speed passenger train service operated by Amtrak as part of its Michigan Services. The 304-mile (489 km) line provides three daily round-trips between Chicago and Pontiac, Michigan, via Ann Arbor and Detroit. It carries a heritage train name descended from the New York Central Railroad.
In railway engineering, cant deficiency is defined in the context of travel of a rail vehicle at constant speed on a constant-radius curve. Cant itself refers to the superelevation of the curve, that is, the difference between the elevations of the outside and inside rails. Cant deficiency is present when a rail vehicle's speed on the curve is greater than the speed at which the components of wheel to rail force are normal to the plane of the track. In that case, the resultant force exerts on the outside rail more than the inside rail, in which it creates lateral acceleration toward the outside of the curve. In order to reduce cant deficiency, the speed can be reduced or the superelevation can be increased. The amount of cant deficiency is expressed in terms of required superelevation to be added in order to bring the resultant force into balance between the two rails.
Positive train control (PTC) is a family of automatic train protection systems deployed in the United States. Most of the United States' national rail network mileage has a form of PTC. These systems are generally designed to check that trains are moving safely and to stop them when they are not.
In railway engineering, curve resistance is a part of train resistance, namely the additional rolling resistance a train must overcome when travelling on a curved section of track. Curve resistance is typically measured in per mille, with the correct physical unit being Newton per kilo-Newton (N/kN). Older texts still use the wrong unit of kilogram-force per tonne (kgf/t).
The Northern Lights Express (NLX) project is a planned higher-speed rail service that would run 155 miles (249 km) between Minneapolis and Duluth primarily in the U.S. state of Minnesota. A portion of the proposed line would run through neighboring Wisconsin to serve Duluth's "Twin Port" of Superior. Plans are to upgrade an existing BNSF Railway freight line to allow trains to travel at up to 90 miles per hour (145 km/h). The train service would provide an alternative to travel along Interstate 35 corridor between Duluth and the Twin Cities.
The minimum railway curve radius is the shortest allowable design radius for the centerline of railway tracks under a particular set of conditions. It has an important bearing on construction costs and operating costs and, in combination with superelevation in the case of train tracks, determines the maximum safe speed of a curve. The minimum radius of a curve is one parameter in the design of railway vehicles as well as trams; monorails and automated guideways are also subject to a minimum radius.
The Michigan Line, sometimes known as the Chicago–Detroit Line, is a higher-speed rail corridor that runs between Porter, Indiana and Dearborn, Michigan. It carries Amtrak's Blue Water and Wolverine services, as well as the occasional freight train operated by Norfolk Southern.
Higher-speed rail (HrSR), also known as high-performance rail, higher-performance rail, semi-high-speed rail or almost-high-speed rail, is the jargon used to describe inter-city passenger rail services that have top speeds of more than conventional rail but are not high enough to be called high-speed rail services. The term is also used by planners to identify the incremental rail improvements to increase train speeds and reduce travel time as alternatives to larger efforts to create or expand the high-speed rail networks.
Track geometry is concerned with the properties and relations of points, lines, curves, and surfaces in the three-dimensional positioning of railroad track. The term is also applied to measurements used in design, construction and maintenance of track. Track geometry involves standards, speed limits and other regulations in the areas of track gauge, alignment, elevation, curvature and track surface. Standards are usually separately expressed for horizontal and vertical layouts although track geometry is three-dimensional.
On the morning of December 1, 2013, a Metro-North Railroad Hudson Line passenger train derailed near the Spuyten Duyvil station in the New York City borough of the Bronx. Four of the 115 passengers were killed and another 61 injured; the accident caused $9 million worth of damage. It was the deadliest train accident within New York City since a 1991 subway derailment in Manhattan, and the first accident in Metro-North's history to result in passenger fatalities. The additional $60 million in legal claims paid out as of 2020 have also made it the costliest accident in Metro-North's history.
The cant of a railway track or camber of a road is the rate of change in elevation (height) between the two rails or edges of the road. This is normally greater where the railway or road is curved; raising the outer rail or the outer edge of the road creates a banked turn, thus allowing vehicles to travel round the curve at greater speeds than would be possible if the surface were level.
On the evening of July 18, 2013, a CSX freight train carrying municipal solid waste on tracks of the Hudson Line along the Harlem River Ship Canal in the New York City borough of The Bronx partially derailed between the Marble Hill and Spuyten Duyvil stations. While no one was injured, the derailment caused over US$800,000 in damage and took several days to clean up. Commuter rail service by Metro-North Railroad, which owns the line, was suspended for two weekends in order to fully restore normal operations.
The first-generation Acela Express trainset is a unique set of vehicles used on the Acela, Amtrak's flagship high-speed service along the Northeast Corridor (NEC) in the Northeastern United States. When they debuted in 2000, the sets were the fastest in the Americas, reaching 150 mph (240 km/h) on 33.9 mi (54.6 km) of the route. They were built between 1998 and 2001 by a consortium of Alstom and Bombardier. Each set has two power cars derived from units that Alstom built for the TGV, and six passenger cars derived from the LRC that Bombardier built for Via Rail.