Education Part 4
Transport
Under construction
Introduction
Concept of Transport
Railroads are transport organizations. Their purpose, therefore, is the movement of entities (freight or goods and people between two points in space-time. As such they are classified as carriers, a topic we discussed in What is a Railroad?.
Purposes
Transport or transportation is the means of moving things from one place to another place in some specified time. There are many sorts of transport, such as movement of water from a water tower to one's home, transport of voice messages from one person to another via a telephone system, movement of people and goods by truck, boat or rail, and so on. Here we are interested in transport by rail.
Transport of goods by railroad involves the movement of large quantities from one place to another. This does not mean that a large quantity need be of just one kind of good in freight transport. Of course railroads transport car-loads of things such as gravel or milk, but bundles of individual items of all sorts, such as automobile parts or tires of various sizes and applications may also be transported, provided the bundle of goods is destined for a particular place.
Transport of people by railroad involves the movement of many people from one place to another such as from Philadelphia, PA to Baltimore, MD (although some may detrain at Wilmington, DE (while others may board there).
Transport also involves the matter of time. Railroad customers would rapidly move to alternative transport if a railroad could not deliver goods in a timely manner. In fact, it was railroads in England that helped establish standardized time by publishing railroad time tables that were based on Greenwich Mean Time (called railroad time) from 1847 December 1.
Legal Matters
The Surface Transportation Board (STB) has broad economic regulatory oversight of railroads, including rates, service, the construction, acquisition, and abandonment of rail lines, carrier mergers, and interchange of traffic among carriers (see Carrier in What is a Railroad?). These various matters are beyond the scope of our discussion but may be mentioned as needed.
Shannondell Model Railroad
Shannondell Model Railroad is a transport system, but only on a model basis. It moves freight and people over its layout but does not actually carry on commerce with any of the entities modeled on the layout.
Introduction
Concept of Transport
Railroads are transport organizations. Their purpose, therefore, is the movement of entities (freight or goods and people between two points in space-time. As such they are classified as carriers, a topic we discussed in What is a Railroad?.
Purposes
Transport or transportation is the means of moving things from one place to another place in some specified time. There are many sorts of transport, such as movement of water from a water tower to one's home, transport of voice messages from one person to another via a telephone system, movement of people and goods by truck, boat or rail, and so on. Here we are interested in transport by rail.
Transport of goods by railroad involves the movement of large quantities from one place to another. This does not mean that a large quantity need be of just one kind of good in freight transport. Of course railroads transport car-loads of things such as gravel or milk, but bundles of individual items of all sorts, such as automobile parts or tires of various sizes and applications may also be transported, provided the bundle of goods is destined for a particular place.
Transport of people by railroad involves the movement of many people from one place to another such as from Philadelphia, PA to Baltimore, MD (although some may detrain at Wilmington, DE (while others may board there).
Transport also involves the matter of time. Railroad customers would rapidly move to alternative transport if a railroad could not deliver goods in a timely manner. In fact, it was railroads in England that helped establish standardized time by publishing railroad time tables that were based on Greenwich Mean Time (called railroad time) from 1847 December 1.
Legal Matters
The Surface Transportation Board (STB) has broad economic regulatory oversight of railroads, including rates, service, the construction, acquisition, and abandonment of rail lines, carrier mergers, and interchange of traffic among carriers (see Carrier in What is a Railroad?). These various matters are beyond the scope of our discussion but may be mentioned as needed.
Shannondell Model Railroad
Shannondell Model Railroad is a transport system, but only on a model basis. It moves freight and people over its layout but does not actually carry on commerce with any of the entities modeled on the layout.
What Runs on the Rails?
Vehicles of various kinds and purposes, called, collectively, rolling stock, operate on the rails of a railroad. Most of these vehicles, called railroad cars, are unpowered. In order for unpowered vehicles to move from source to destination, they must be pulled or pushed by vehicles that provide motive power. In very early times motive power was supplied by gravity, by horses, or by people. Today, such power is supplied by vehicles called locomotives (sometimes engines) that derive their energy from fossil fuels, nuclear, wind, hydroelectric or other sources.
If the unpowered vehicles or railroad cars carry freight or goods, they are likely to be pulled/pushed by diesel-electric locomotives, although in some parts of the world, steam power is still in use (but in decline).
If the unpowered railroad cars carry passengers they may be pulled or pushed by electric locomotives, except on long runs where infrastructure costs still favor diesel-electric motive power.
In general, railroad cars that carry freight or passengers are classified as revenue-producing rolling stock. Motive power is not, of itself, revenue producing, nor is Maintenance-of-way stock.
Vehicles of various kinds and purposes, called, collectively, rolling stock, operate on the rails of a railroad. Most of these vehicles, called railroad cars, are unpowered. In order for unpowered vehicles to move from source to destination, they must be pulled or pushed by vehicles that provide motive power. In very early times motive power was supplied by gravity, by horses, or by people. Today, such power is supplied by vehicles called locomotives (sometimes engines) that derive their energy from fossil fuels, nuclear, wind, hydroelectric or other sources.
If the unpowered vehicles or railroad cars carry freight or goods, they are likely to be pulled/pushed by diesel-electric locomotives, although in some parts of the world, steam power is still in use (but in decline).
If the unpowered railroad cars carry passengers they may be pulled or pushed by electric locomotives, except on long runs where infrastructure costs still favor diesel-electric motive power.
In general, railroad cars that carry freight or passengers are classified as revenue-producing rolling stock. Motive power is not, of itself, revenue producing, nor is Maintenance-of-way stock.
Motive Power
Pulling Power or Tractive Effort
Motive power amounts to the energy needed to move a train. This power may be called pulling power or (better) tractive effort. Tractive effort is the energy needed to overcome friction, which arises from several points. For one, there is the friction of the bearings that facilitate the turning of the axels of the rolling stock. While the object of the bearings is to minimize this friction, it cannot be reduced to zero. On a long train with many axels, bearing friction is significant.
Another source of friction is that of the wheels against the rails. Such friction is absolutely necessary if the train is to be moved or stopped. But it is also a cost in tractive effort necessary to overcome wheel/rail friction. A related source of friction is called truck hunting (bogie hunting) in which an oscillation occurs as the wheels of the truck "hunt" for lateral equilibrium. This oscillation manifests itself as swaying of rolling stock and is a cost in tractive effort.
Another source of friction is the air through which a train must pass. Aerodynamic friction is meaningless when the train is stationary, but it increases as the square of the velocity of the train when in motion.
Finally, there is a friction due to gravity. On a grade of 0° the friction due to gravity is a constant that provides the adhesion (wheel/rail friction) necessary for a train to move. But if the grade is greater than 0° there will be a cost in tractive effort necessary to overcome the force of gravity. If the grade is less than 0°, then the force of gravity contributes to the tractive effort.
Measuring Tractive Effort
Tractive effort is determined by the equation
Fmax = coefficient of friction × weight on drive wheel
where the coefficient of friction for steel on steel typically ranges between about 0.35 to 0.5. Fmax will have the dimension Newtons (N) which is a measure of acceleration such that 1N = 1 kg⋅m/s/s. In words, one Newton is the acceleration of one kilogram of mass 1 meter/second per second. For motive power, consider a locomotive with mass 50 tons (45359 kg) operating under a coefficient of friction of 0.4. Weight on drive wheel will be 45359 kg x 0.4 = 18143 N or 18.143 kN.
For practical purposes, there are two types of tractive effort, starting tractive effort and continuous tractive effort. It takes more effort to start a train from stand-sill than it does to keep a train moving once started. There is also a point at which, if acceleration continues, the train will eventually reach a velocity at which the available tractive force of the locomotive(s) will exactly offset the total drag (sum of friction components), causing acceleration to cease and the train will run at a constant velocity as long at the tractive effort remains constant.
For modern motive power, a different approach to measurement of pulling power may be used. Railways now use dynamometer cars to measure tractive force at speed in actual road testing. This provides a more accurate and realistic measure of a locomotive's ability to move a train. Today, motive power can be expressed in kiloNewtons (kN), watts or horsepower (see table below).
Types of Motive Power
For all practical purposes, there are three types of motive power, namely
steam, diesel and electric. The fuel for steam locomotives can be anything that burns at a high enough temperature to convert water into steam. Although coal has been most common, wood, oil and other fuels have been used. To our knowledge hydrogen has not been used although it has been explored for automobiles. Nuclear fuel has been explored but considered economically infeasible.
Fuel for diesel locomotives is diesel oil. While there have been constructed diesel locomotives in which the diesel engine directly drives the axels of a locomotive, virtually all diesel locomotives today are actually diesel-electric. In such locomotives, the diesel engine drives a generator or alternator that provides electrical energy to the axels through electric motors. For our purposes, only diesel-electric locomotives will be considered.
Fuel for electric locomotives may be fossil fuels (coal, oil, gas), nuclear energy, hydropower, wind power, or solar power. Batteries have been used in situations where wired electrical transmission is unavailable such as in maintenance of overhead catenary lines when they must not be powered or in situations where other power would be hazardous (e.g., mines). Battery-powered trains may become more important as storage and charging capacities improve and as environmental concerns become more serious.
The following table gives the motive power of selected locomotives. We turn next to information on steam locomotives.
Selected locomotive weight and power
Steam Locomotive
The steam locomotive is a marvel of engineering. Although very largely historical at this point in time, it is instructive to study the basics of steam locomotives. Every steam locomotive consisted of a frame upon which to support a fire box that heated water to steam in a boiler, a cab in which the driver and support staff worked, a set of wheels upon which these components rested, plumbing, control mechanisms and other components. The following illustration identifies 48 different but integrated components of a steam locomotive.
The steam locomotive is a marvel of engineering. Although very largely historical at this point in time, it is instructive to study the basics of steam locomotives. Every steam locomotive consisted of a frame upon which to support a fire box that heated water to steam in a boiler, a cab in which the driver and support staff worked, a set of wheels upon which these components rested, plumbing, control mechanisms and other components. The following illustration identifies 48 different but integrated components of a steam locomotive.
Main components of a typical steam locomotive
A description of the numbered components is given in the following table.
Description of the keyed components in the above illustration
Diesel-Electric Locomotive
Electric Locomotive
Maintenance
Rolling Stock Manufacturers
Companies manufacturing locomotives in the United States included Baldwin Locomotive Works, American Locomotive Company (ALCO), Lima Locomotive Works, and Altoona Works. Altogether, between 1830 and 1950, over 160,000 steam locomotives were built in the United States, with Baldwin accounting for the largest share, nearly 70,000.
Famous Locomotives
Famous Trains
Electric Locomotive
Maintenance
Rolling Stock Manufacturers
Companies manufacturing locomotives in the United States included Baldwin Locomotive Works, American Locomotive Company (ALCO), Lima Locomotive Works, and Altoona Works. Altogether, between 1830 and 1950, over 160,000 steam locomotives were built in the United States, with Baldwin accounting for the largest share, nearly 70,000.
Famous Locomotives
Famous Trains
Unpowered Railroad Cars
Source of Revenue
Types (Freight vs. passenger)
Carrying Capacity (weight vs. seats)
Basic Construction Principles (Freight vs. passenger)
Maintenance
Source of Revenue
Types (Freight vs. passenger)
Carrying Capacity (weight vs. seats)
Basic Construction Principles (Freight vs. passenger)
Maintenance
Maintenance-of-Way Vehicles
Non-revenue
Types
Basic Construction Principles
Non-revenue
Types
Basic Construction Principles