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Bernard P. Markowicz, PhD.
introduction
Railroads are increasingly recognized as a driver of economic development. In the United States, impressive improvements in productivity have turned the freight rail industry around
and made it successful again. For example, between 1983 and 1993, productivity in the industry jumped 157%. At the same time, revenue increased 32% and rates fell 40%. Today, virtually all of the 500-plus
surviving U.S. railroads are making money.
In developing countries, railroads play a key role in the growth of the economy, as road congestion and lack of heavy-haul roadway infrastructure prevents effective linkages between
major economic centers and port areas.
The last decade has also seen increased pressure on publicly owned railway systems to be self-sustaining and profitable – resulting in several countries undertaking
privatization initiatives, which, in turn, have sparked investment in, and modernization of, these systems.
The objective of this monograph is to look at the major forces affecting the ability of rail systems to meet the demands of their customers in the 21st century, and to propose
an approach that will help rail systems address the effect of these forces.
major forces affecting rail operations today
Like other enterprises today, rail systems face competitive pressure in virtually all types of services they offer:
One of the compelling ways to address these competitive and operational pressures is to increase a rail system's network operating capacity. Increasing network capacity will
enable railroads to attract more market share safely, maintaining passenger and freight service reliability, reducing contention between passenger and freight by improving throughput, and improving productivity
and safety by alleviating congestion.
key drivers of rail network capacity
There are several ways to improve overall network operating capacity –some by adding new infrastructure, other by increasing the operating capacity within the same
infrastructure. New line and yard tracks can be added. These actions are usually expensive and may take a long timeLarger freight or passenger railcars can be introduced to increase capacity for some services.
This often requires changes in infrastructure as well, such as road bed and signals. Longer trains can be introduced. Longer trains are usually slower, and may require extensive changes to the infrastructure
such as signals and sidings. More trains can be added over the existing infrastructure. This may require changes to the dispatching and train control systems. This last option is often the most economical
because it requires the least amount of investment in tracks and equipment. However, the number of trains running over a track segment within a period of time is limited by train control systems, and
in particular by the need of these systems to maintain safe distances between trains.
A new type of train control system, known as positive train control system(PTC) allows distances between trains to be safely reduced, thus enabling rail systems to
dramatically improve rail line capacity, and transforming the economics of rail transportation. Current and New Generation Control Systems Traditionally, trains have been controlled over remote territory by a
combination of signals and direct instructions to the engineer in the locomotive cab. In so-called dark territory, covering over half of the US, trains are controlled by voice instructions, or fax transmissions
of written instructions, from dispatchers to locomotive engineers. This is known as Direct Train Control (DTC).
The most active rail lines (the other half) are controlled by a variety of signal systems. Of these lines, two-thirds are equipped with systems that enable dispatchers to
remotely control switches and the signals that are co-located with the switches, known as Central Train Control (CTC). Less than 5% of route-miles in the US has systems in place where signal indications are
shown in the locomotive cab or there is on-board enforcement of the signals, or both.
These signaling systems are based on a scheme that blocks out large fixed segments of tracks whenever a train or maintenance crew occupies any space in that block. For
instance , as soon as merchandise train Q101 enters a 20-mile fixed block, the signals at both ends of that block will turn red (or its railroad equivalent), preventing any other train from entering the block.
No train will be allowed in that block until train Q101 has completely exited the block, maintaining physical distances between trains and preventing collisions
If train Q101 is 100-cars long, and travels at 40 miles per hour, it will take about 32 minutes for the train to clear the block, and for the next possible train to enter the
area. If we could safely reduce the time lag between trains from 32 minutes to, say 15 minutes, the capacity of the line could be increased by over 100%.
Positive train control systems attempt to do just that. These systems rely on constant two-way communications between a centralized controller and each train or equipment on
the track, in order to monitor and control position and velocity. By knowing at all times exactly where all trains are, and how fast they are going, the centralized system can help maintain safe distances
between them. In its most elaborate form, PTC provides complete remote control of trains over the right-of- way, controlling speed or applying emergency brakes as required.
A PTC system will not only enable trains to be safely separated as a function of their respective speeds, but it will further enhance train operations through train
pacing and real-time management of meets and passes and dispatching of trains from terminals.
The concept of positive train control is not new. It has been successfully implemented in the Vancouver and London rail transit systems, and will soon be deployed in New York
and San Francisco. It has not yet been implemented on a large freight rail carrier, where its application would have significant economic impacts.
Three factors made it possible to deploy positive train separation systems in rail transit networks: 1) the total length of the system is relatively small compared to
a regional or national rail system, 2) transit systems are formed of single, independent lines with few or no inter-connections, and 2) the transit system right-of-way is dedicated and, at all times, under
complete control of the operating entity.
The primary reasons why such systems have not been implemented on more expansive rail networks to date are the technology and cost of both the central brain and of the
fail-safe communication system required to provide reliable redundant communications between trains, signals and centralized control. The Railroads' Challenge Current approaches to providing fail-safe
two-way communications to support positive train control span a number of media: microwave links, satellite links, RF- based wireless, copper and fiber-optic circuits, dedicated VHF and UHF channels, as well as
wayside transponder-based systems. Moreover, each proposed system uses its own combination of technology, dedicated, proprietary communication protocol and fail-safe mechanisms, each with its own set of
technical limitations (for instance, low frequencies require large antennas, and very high frequencies offer limited ranges in rough terrain or tunnels.)
At the same time, other segments of the economy are placing increasing pressure on the available spectrum: Competition for wireless is becoming intense, and other
transportation sectors, such as air and emergency services, are increasingly information-intensive, demanding additional spectrum. In the United States, the response from the Federal Communication Commission
(FCC) to this increased demand for communications has been to "refarm" the available bandwidth into narrower channels, requiring more sophisticated technology.
Finally, the benefits of a positive train control system can only be fully derived when an entire system (including all tracks, signals and locomotives) is equipped with it, as
opposed to a line, division or other system subset
The challenge facing railroads in building a telecommunication system to support positive train control is three-pronged: How to build a technologically mature, reliable and
fail-safe system, providing high levels of performance and capable of evolving over time. How to build a cost-effective system, from an investment as well as a maintenance standpoint, and how to build a highly
inter-operable system, allowing trains to cross national boundaries, or run across multiple private companies.
moving ahead…
Historically, railroads have relied on proprietary signaling technologies and on dedicated radio channels for communicating with locomotives and signals. In the United States,
standards were developed over time under the auspices of the Association of American Railroads and the Railroad Radio Service to manage spectrum and dedicated frequencies. Radio is an established technology
that meets todays' operating needs, and it has evolved little in the past ten years. Designing and implementing the digital telecommunication system required to support PTC represents a significant risk and
investment that senior railroad management has been unwilling to take to this point.
During the same period, commercial fiber and wireless telephone and telecommunication service providers have made quantum leaps in performance, cost and reliability. Such
recent improvements include
- Airlines compete increasingly with long-distance passenger rail systems
- Truck compete with railroads for the short and medium distance haulage of freight
- The major competitive forces affecting rail system operations can be placed in three categories:
service:
All customers are demanding on-time performance and reliability over
time. A segment of customers are demanding flexibility and the ability to change shipping or traveling plans rapidly and without hassle. Rail systems must improve on-time performance and reliability, and the
ability to plan flexibly for operations.
productivity:
Customers demand low transportation rates or fares, and are
increasingly sophisticated in their ability to leverage competitive options. Shareholders demand return on investments that are commensurate with other industries and with other modes of transportation. As a
result, rail systems must continue to improve productivity, in order to lower operating ratios, offer competitive rates and fares, and regain market share.
safety:
Both shippers and passengers demand systems that are safe for cargo and people, and factor safety and damage in their mode or carrier selection decisions.
In addition to these competitive forces, and in part as a result of them, other operational pressures are building on the rail systems as well. As railroads pare down assets to
improve productivity, and as freight and passenger volumes grow,
There is increased contention between freight and passenger service: Passenger trains are required to move faster, on-time. Slower freight trains often block the way, or block an
inordinate amount tracks for long periods of time
There is increased yard and line congestion, because trains and railcars are required to move faster and there is less slack in the schedule, and less room to maneuver. Congestion
creates unpredictable delays and damages operational reliability. Congestion creates additional costs such as worker overtime
There are increased incidences of accidents because operating parameters are tighter and safety is harder to maintain
SONET (Synchronous Optical Network) and ATM (Asynchronous Transfer Mode) standards that are now incorporated into core networks, multi-tiered restoration architectures designed to
recover from fiber cuts and span failures in milliseconds, extensive use of "out-of-band signaling" to carry information about a call, its destination, and whether it needs special handling
Software defined networks (SDN) enabling large business customers to use the switched network as though they controlled their own private business network
Breakthroughs in cellular technology provide reliability and affordability approaching land lines
A detailed review of the current state-of-the-art of commercial telephony would show that the major commercial telephone service providers have the technology and wherewithal to
provide the capabilities and performance required to support PTC now.
The answer to the PTC communication challenge is therefore simple: rather than trying to build a dedicated infrastructure themselves, railroads should leverage the technology
and infrastructure provided by commercial telephone service providers. Railroads should specify a set of business requirements to support PTC, and partner with one or several major service providers
to implement a system that meets these requirements.
in summary
Railroads have become, once again, key drivers of national economies. Improvements in labor and equipment productivity, as well as the rationalization of old networks, is driving highway freight
back to the rails. In developing countries, passenger railroads must compete with airlines by offering more reliable service, resolving increased contention for the right-of-way between freight
and passenger service.
Positive train control is a communications-based technique that will enable railroads to respond to
these economic pressures by improving capacity substantially, without requiring additional tracks or yards.
The main obstacles to the development of positive train control systems on large railroads are the
risk and cost associated with the deployment of a fail-safe digital communication system, linking centralized or regional control centers with each moving locomotive on the system.
This monograph argues that railroads should look to the main commercial providers of telephony
services to supply the telecommunication services and infrastructure required to run positive train control, thus minimizing risks to the railroads, and ensuring inter-operability between systems.
Notes:
"Back on the Track for the Future," Los Angeles Times, February 27, 1997.
Variations of this system are also known as positive train separation system in the United States, or communication-based train control systems in Europe
Federal News Service, March 27, 1996,
Prepared Statement by Jolene Molitoris Before the House Committee on Transportation and Infrastructure. Draft 7 10/04/97
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