“There’s nothing vital in dark territory.”
My Railroad Immersion Course has been used by railroads and suppliers alike to obtain a new perspective of railroad operations based upon advancing the traditional core technologies of communications, positioning, and intelligence, i.e., wireless voice, track circuits, and Computer Aided Dispatching (CAD), respectively. When giving the course to traditional traffic control suppliers, I address the difference between signaled and non-signaled operations (a.k.a., dark territory). Consistently, there is a point in the course where it makes a transition from a one-way lecture to a very interactive discussion. Specifically, it is when I ask the question: “So! What’s vital in dark territory?” Without fail the response is “There’s nothing vital in dark territory.” And, with as much detente that my personality permits, I respond “Really?”
From their perspective there is an understandable reason why traffic control suppliers would respond as such in that dark territory operation is one in which they have little to no experience in that there is no wayside infrastructure required, and hence there is nothing for them to sell. Additionally, the term vitality to these folks has a very product-oriented perspective of failing safely, i.e., to not place the railroad in the position of additional risk upon a failure in the signaling infrastructure. Therefore, their logic would be that since there is no product along the wayside, then there is no vitality. Voila!
What traffic control suppliers don’t consider is that vitality has also a functional perspective of insuring the integrity of train movements … which more specifically means that the movement authorities are generated in a fashion that provides for safe train movements; that indeed is the underlying requirement of signaling infrastructure after all. Therefore, to answer the question of what is vital in dark territory means identifying the source of movement authority generation. This is where the discussion really takes off.
Usually the second answer offered by the class is “The dispatcher is vital.” Wrong!. Just as in signaled territory, the dispatcher does not generate the authority and therefore is not vital. He does indeed set up the authority generation process, as well as deliver the authority via voice radio. But, he does not generate the authority. In the old days, authority generation in non-signaled territory was provided by the train sheet, which is literally a piece of paper, upon which the dispatcher managed the allocation of track distance and time. The dispatcher abided by what the train sheet permitted him to do or not do as to the allocation of track. Today, the movement authority generation is a computerized program, a.k.a., conflict checker, that emulates the train sheet. The underlying logic of either the track sheet or the conflict checker cannot be simpler. That is, a specific portion of track can only be allocated to one train at a time. That’s it (with some exceptions that are not important here). That’s vitality in dark territory. Should the dispatcher wish to override this vitality in some fashion, then s/he has now become vital. But wait, there’s more.
Once everyone is satisfied with that understanding, I move onto Automatic Block operation (ABS) which is the use of signals within dark territory operation, what I refer to as dark / lighted operation. In ABS, the signals function the same as they do in CTC territory, but the dispatcher is not provided with the aspects. Hence, it is dark to the dispatcher, but lighted to the train crew. Now the question to the class is two-fold. First, “Is ABS signaled operation or dark operation?” Second, “What is vital in ABS operation?” Those individuals who have been following the discussion up to that point usually respond quite well to these two questions. However, for hardcore signal engineers it is difficult to realize that the overall operation is dark (officially so) in that the initial movement authority to get the train into ABS was provided by the conflict checker. However, once in ABS, the train is subjected to a second level of authority from the signal infrastructure. Hence, there are two levels of vitality. But wait, there’s more.
Once everyone is satisfied as to ABS, I now introduce the concept of work zones where maintenance crews have the authority for a portion of track for a given period of time. The question to the class then is “What’s vital in a work zone?” Hopefully, by now they are able to respond that the Employee in Charge (EIC) of the work zone adds an additional level of authority to the train that has the movement authority generated by the traffic control system to move through the area. That is, the train crew must request permission by the EIC to enter the work zone when that zone is in effect. Hence, the EIC is vital within the work zone. But wait, there’s more.
After this discussion, the class is now thinking about vitality from a functional standpoint. This leads to two more questions for their consideration … and which leads to forthcoming Teddy Bear Posts regarding the vitality of PTC and the vitality of transmitting authorities in non-signaled operations. By the way,check out a brochure for the Railroad Immersion Course.