Traffic Movement: Safety vs. Management

Recently on this blog I posted the article Dangerous Railroading in which I identified 4 primary areas that a railroad needs to address for safe operations, i.e., 1. choice of safety systems deployed, 2. critical infrastructure maintenance practices, 3,  personal / personnel accountability, and 4. theft of critical infrastructure. The primary point of that posting was that a railroad’s slack in any one of the four areas would result in the safety of its operations being readily compromised. In that posting I addressed each of the areas in a cursory fashion with the commitment that I would address each in greater detail in subsequent postings. As such, this posting addresses safety systems with additional discussion as to Traffic Management.

There are two levels of safety systems to consider for the movement of trains from both the dispatching and train crew’s perspectives, i.e.. traffic control and enforcement, respectively.


Simply stated, traffic control is the functional vitality of the railroad that ensures the integrity of train movement authorities. It does that by employing vital logic / hardware / systems that generate the movement authorities in a fashion that fails safely, i.e, unsafe authorities are not delivered. I am purposely pointing out the difference between functional vitality and logic / hardware / system vitality here in that the distinction is often overlooked, if even recognized by many railroaders. Logic / hardware / system vitality is that which signal engineers solely identify with. Too often, signal engineers mistakenly believe that signals are installed for safety purposes.  Of course, signals provide for safety, but they are installed for traffic throughput in that it is possible to operate a railroad safely without signals, e.g., 50% of the trackage in the US is non-signaled traffic control. … as is ETCS level 3, … as is the most primitive token block system.  Signal engineers don’t identify with functional vitality, a point which is quickly proven by asking ANY signal who has not taken my Railroad Immersion Course (brochure is available on the blog),  “What’s vital in non-signaled (dark) operations?”  Their response will always be “Nothing!” since there is no hardware installed along the wayside.  They are so, so wrong from a functional standpoint.  Vital functionality is what a railroad requires, and the vital logic / hardware of signaling systems is only one way to achieve that. (Further discussion on this point, as well as the answer as to what is vital in dark territory, is provided in a previous posting on this blog in the Teddy Bears category: There’s Nothing Vital in Dark Territory).

Arguably, the most disturbing issue currently about traffic control is the willingness by too many railroads to blindly accept both the traditional and advanced traffic control systems that are offered to them by traditional suppliers pushing what they have, versus what those railroads really require. I am not referring to high speed, high capacity operations as in Europe’s passenger operations where interoperability and traffic density are the driving factors. Rather, I am referring to all of those railroads across the other 90% of the globe that are struggling to develop a core transportation infrastructure to expand their country’s economy. How dare traditional signaling companies and consulting firms provide only products that feed the seller’s bottom line instead of pragmatic cost-effective solutions that service a railroad’s bottom line. These suppliers are providing, as well as the consultants are promoting, products instead of true solutions. (Again, I refer you to another posting on this blog: In the Light of Dark in the Railroad Business category.)


Unlike traffic control which is meant to prevent dispatching errors, enforcement is meant to prevent train crew errors. Simply stated, enforcement systems monitor the status of a train’s movement relative to its authorites. Should the system determine that the train is in jeopardy of violating an authority as to some combination of speed, distance, and time, then the enforcement system takes some combination of actions such as warnings to the crew, slowing the train, or bringing the train to a complete stop. As such, enforcement functionality can be integrated with advanced traffic control systems such as ETCS in Europe, or it can provided as an overlay system, as is the case with PTC in North America. In any event, enforcement systems are not vital as to functionality or logic / hardware (as discussed above) in that they do not generate authorities. Should, the enforcement system fail in some fashion, then the train is no less safe than it was without the enforcement system . . . Well! Almost always. One possible exception is that of an improperly designed enforcement system that makes an emergency brake application that for some reason results in a derailment.

Various types of enforcement systems have been in use in passenger operations for decades. However, for freight operations across most of the globe, enforcement systems have been extremely limited in their deployment and functionality compared to what is now available with PTC and the European flavor of Automatic Train Protection (ATP) as well as enforcement functionality incorporated in ETCS for Europe’s High Speed Passenger operations. What is unique about PTC relative to ATP / ETCS, is that no significant additional wayside infrastructure (other than a commercial or private wireless data network) is required for a very basic approach in signaled territory, with only switch monitors required in non-signaled operations.   NOTE: For the hardcore PTC followers who feel tempted to correct me regarding WIU’s being required in signaled territory, I request that you first think about why WIU’s are needed if interim signals are not enforced.


Neither traffic control nor enforcement is traffic management.  Traffic management deals with the efficient generation of authorities, but not the generation itself. It is designed to meet the operating directives (business value) of the railroad in managing the key resources, and as such has nothing to do with the safety of the railroad. Until recently, traffic management has been dependent upon the analytical and the rationalization of a railroad’s management team as to what was most important, i.e, moving high priority trains regardless of the cost associated with other traffic. It has only been within the last decade that advanced traffic management has introduced the mathematical tools that can displace the limited human-mentality of dispatchers to deal with the most simplistic prioritization of track time only, yet alone consider fuel utilization, crew availability, balance of locomotive distribution, and the constraints of track maintenance. I should point out that I am referring primarily to non-scheduled operations that are prevalent in North America.  I am not referring to high speed passenger operations that are highly scheduled. (One more time, I offer two other postings on this blog relative to traffic management, both from the Teddy Bear category: 1) CAD Delivers Traffic Management, and 2) Train Dispatching is too Difficult for that Math Stuff.

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3 Responses to “Traffic Movement: Safety vs. Management”
  • In that blog post, I very like the clear distinction between traffic control, enforcement, and traffic management. Everybody in the signaling industry should read this. A lot of misconceptions and misunderstandings are based on the fact that in the signaling industry, there is still a culture of thinking in technologies (i.e., products) instead of thinking in functionalities. This often leads to the misconception that functionalities and technologies are the same. The key point everybody should understand is, that the same function can be effected by completely different technologies or even without technology, i.e., just by operating procedures.

    A few words on European ATP and ETCS. In Europe, concerning ATP, there is not that distinction between freight and passenger railroads. As an example, in Germany, an intermittent ATP system with continuous braking curve supervision (including brake enforcement) for a train approaching a stop signal is required by law for all lines with a speed of more than 100 km/h (62.5 mph). No locomotive, no matter if passenger or freight, must be operated on the German network without such an ATP device onboard. Freight trains using high speed lines, either in mixed traffic with high speed trains, or at night hours, are even equipped with the continuous ATP system, which is known as LZB and based on data transmission by a trackside cable antenna.

    ETCS at the level 1 (data transmission by controlled transponders) and level 2 (data transmission by GSM radio), which is still based on fixed block, is a pure ATP system but does not generate movement authorities. In these ETCS levels, movement authorities are still generated by traditional CTC systems. In ETCS level 2, these movement authorities are transmitted to a Radio Block Center, which transforms them into an electronic format that is transferred to trains by radio. The term Radio Block Center is a little misleading since it provides no block functionality. Actually, it’s a pure Radio ATP Center that does quite the same as the central control unit of the current German LZB system. Only in ETCS level 3, which is based on moving block, movement authorities are generated by the Radio Block Center using train location data. In level 3, CTC is still used for interlocking but no longer for safe train separation. However, there is currently no European railroad that has any plans for ETCS level 3. Everything is based on level 1 and 3. Thus, ETCS will just replace existent national ATP systems by an interoperable ATP that eliminates the need for expensive multiple equipped locomotives for cross-border operations.

  • Joern
    Thank you again for your comments and additional explanation of RBC which was a new term for me until last week when I received a message from a colleague to discuss it.

    As to signal engineers reading this posting, I encourage you to spread the word about this blog amongst your colleagues .. and they with their colleagues. Of course I really encourage all to take my course, Railroad Immersion Course, as described in a brochure on this blog where all of these points are covered in detail. Companies that have taken the course include the most traditional railroad suppliers, including Bombardier, Alstom, Ansaldo, Lockheed Martin, and Wabtec, as well as other notables including IBM, Cisco, Motorola, and Selex. So many engineers, so little time.

  • Ron,
    I already recommended your blog to several people. Retweeds of your announcements in my Twitter network may also help. While living in Europe, as a member of the TRB Railroad Operating Technologies Commitee I’m also a regular visitor of the USA and quite familar with the current PTC discussions.

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Given recent tech advances there is now an unprecedented opportunity to advance railroad operations and the integration of high speed rail with freight. Real-time traffic management and communication is possible without significant development and deployment costs, but it will take a technology strategy working hand-in-hand with an operational strategy, it will take Strategic Railroading.™
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