Ten90 Solutions LLC

In the beginning...there wasn't light.  There was only dark...territory. The fundamental business process of the railroad which is to authorize the movement of a train was carried on in "darkness."  The actual, real, field movement of the train was more or less hidden, opaque to the issuing authority.

Of course, the railroad's business process was never just about issuing a movement authority to a single train.  It has always been about issuing multiple authorities for the movements of multiple trains. And so the fundamental business process takes us directly to the vital operating process of the railroad: issuing movement authorities such that no two (or more) trains hold overlapping or conflicting authorities.  The safe separation of train movements is what I mean when I talk about vitality on the railroad. 

 (Full disclosure:  Mine is probably a minority view.  As far as I can tell only Ron Lindsey holds a similar view of railroad vitality).   

So what's the essential information, data,  for establishing non-overlapping, non-conflicting authorities for train movement?  TRACK OCCUPANCY.  The determination of occupancy and granting authority for occupancy is what it's all about.  Train control is the subordination of train movements to the conditions of occupancy. 

In the beginning...there was no way to register, capture the conditions of actual occupancy and communicate those actual conditions to following, or opposing trains.  The separation of authorities was "virtual" with vitality residing in the operating rules, the timetable schedule and special instructions, train registers, and made real through the compliance of the operating crews with those requirements. The "office" conditions, of the timetable, the operating rules, were presumed to be one with the field conditions.  Certainly, the rules required field actions when trains could not fulfill their authorities properly.  Flagging requirements were critical.  Still, there could be an overlap of authorities that would remain invisible to the field in the event of human failure.  

Part of the reduction in the risk of the violation of movement authorities  was accomplished in establishing a means of communication between field and office, between train and station, between and among stations networked so that train movements could be reported and in case of a failure of "correspondence" between field and office, the movement authorities of other trains could be modified, restricted, or even suspended at intermediate locations. Still, even with enhanced, human error in this network of communication and control could create overlapping or conflicting authorities.

The greatest advance, and in my opinion still the single most important contribution to safe train operations, was made with the invention and application of the closed track-circuit.  This invention registered, recorded, and communicated the field condition of occupancy separately and independently from the office.  The advance of the closed circuit into a system of such circuits established the superiority of field conditions to the office record.

Vitality was now maintained in the field by the field apparatus.  Since then, again in my opinion, the advances in train control in US rail operations have all enshrined this separation of field and office.

So...the determination of occupancy is vital; the track circuit is vital.  Are signals in an automatic block signal system, driven by the closed track circuits vital?  There are two answers to that question and both are yes.  Yes (1) because we make them vital when we write in our rule books something like: "In territories so designated by the timetable, signal indications will be the authority for train movements (in the same, or both directions), and will supersede the superiority of trains."  Yes (2) because the signal indication is the field communication of the condition of occupancy.  

It from this perspective of operating vitality, the elimination of the risk of overlapping authorities, that we derive the concept of hardware vitality-- that a vital piece of equipment, for example a signal in an automatic block signal system, must fail safely. When fault or damage prevents the component from operating as designed, it must default to the condition that involves minimal risk to safe train separation.  A signal that fails and displays its most restrictive indication is a safe signal.  It does not create the conditon of overlapping or conflicting authorities for movement. 

I go through this exercise here, repeating much of what I written before, because I go through this exercise daily, almost, in my own head when trying to sort the advantages and risks new systems of identifying train locations present to safe train operations.   I go through this exercise when trying to imagine what GPS system identification of train location in "dark" territory might lead to.   

First and foremost, GPS systems are not, to my knowledge, being utilized to determine, register, or communicate, train entry, occupancy, or clearing of a section of track. 

There is no doubt that GPS system data can be integrated into a model display of a railroad to provide more immediate, more precise information regarding train location to the office. Indeed GPS systems can provide details of train location more precise than a track circuit.

My concern is not that somewhere at some time, someone might want to integrate the GPS system data with the office display when it comes to "dark" territory. Such integration makes sense, once the GPS system is enhanced to register "train integrity"-- that the train has not separated, that the end of the train is truly end of the train. Ron Lindsey's "V-CTC"-virtual CTC- visualizes doing just that.   

My concern is that the data might be utilized to provide an "automatic roll-up" of authority for trains moving in dark territory, indicating  that the section is clear prior to the crew's own report of "clear"-- and that "automatic roll-up" might be followed by "automatic clearing" for a following or opposing movement.  In that case, we have made GPS systems the vital component for train movements.  Now GPS system accuracy and reliability may be greater than crew members who after all are a major source of human error, but I don't know that I'm comfortable with the vitality of my railroad residing, literally, off-world. 

David Schanoes 

October 13, 2018

"We must go on," Kane, Alien