Railway and train operating environment: Background and basics
At this juncture, there is just a glut of train traffic moving over America’s approximately 140,000-route-mile rail network and the system has gotten bogged down.
Congestion? We don’t often associate that idea with railroads. But like on motor vehicle platforms, railroads are not immune either. Capacity is the operative word here and finding the correct solution to increase it sufficiently is one of the challenges.
And then there is the safety aspect. And relatedly, just this past Aug. 17th at 3 a.m. two freight trains collided head-on in Hoxie, Arkansas. It could be months before a cause or causes are determined and a corresponding statement released. A similar incident happened in June 2012 in the Oklahoma panhandle region. While in the former two of four crewmembers total lost their lives (the other two sustained injuries but survived), in the latter, again, of four crewmembers total, only one survived. Railroads could be made safer in my opinion and in so doing this could be far-reaching in terms of improving overall system functionality.
So, first question: How can all this rail traffic be moved more safely, efficiently and cleanly than what is the case already? Next: Does all of this traffic traversing the rails really need to be moved more safely, fluidly and cleanly than what is the case already? I believe it does.
In “CATS: In ‘passing’: On ‘track’ to trim emissions” I penned: “One of the strategies railroads employ to mitigate air pollution is to cut delay. And, I am not just talking about so-affected motorists delayed while waiting for trains to pass at highway-level crossings (railroad crossings), but those operational inefficiencies within the industry itself; operational inefficiencies such as that which can occur at interlocking plants (junctions) whereby one railroad’s trains might be delayed by another’s in going through and past such interlocking until such time that the waiting train can proceed through such itself.
“Another would be that which is created by conflicting train movements as is common-place in single-track territory that incorporate passing sidings used as a means to get trains traveling in opposite directions past each other.”
It is the latter condition on which I will focus as it has to do with Positive Train Control or PTC. I earlier discussed other air-pollution mitigation strategies.
PTC: What is it?
From the Federal Railroad Administration document: “Quantification of the Business Benefits of Positive Train Control,” prepared for the Federal Railroad Administration by ZETA-TECH Associates, Mar. 15, 2004 revision, as presented in the “APPENDIX A: Acronyms and Abbreviations” section, PTC is described as follows:
“Positive Train Control (PTC) – A generic term (and acronym) used to describe any processor-based system of train control that will: (1) Prevent train-to-train collisions (positive train separation); (2) enforce speed restrictions, including civil engineering restrictions and temporary slow orders; and (3) provide protection for roadway workers and their equipment operating under specific authorities.”1
Meanwhile, more on PTC is found earlier in the document in the “Executive Summary,” Definition of Positive Train Control subsection beginning on page 5.
For purposes of this discussion, PTC and what effect this could have on line capacity is what is being explored.
Line Capacity: How is it determined?
Line capacity is affected by such factors that are both route- and location-specific, such as line curvature and gradient, train speed, signal-control type and the mix of rail-borne traffic.2
In the FRA document, line capacity, it is further stated, can be increased in either of two ways: by adding track or through signal system improvement.3
It is important to note that by incorporating a system of preventing train collisions and at the same time reducing the distance between trains and maintaining system integrity meaning the safe operation of trains is maintained, the opportunity exists to increase railway track capacity and PTC can assist in helping to bring this about.
Elaborating further, the FRA in the document noted: “Dynamic headways can increase line capacity by permitting shorter and lighter trains to operate on closer headways, rather than constraining all trains to the separation by the longest and heaviest trains. … Dynamic headways can also, in conjunction with a local tactical planner reduce average running times. For instance, a 20% reduction in run time means that a train which used to take five hours for a trip will now take four hours. This provides an extra hour when the track is free to run another train. Any reduction in run time produces an equal increase in track availability.”4
From what I understand, a federal mandate is in place for the nation’s railroads to have between 70,000 and 80,000 route-miles of the industry’s total 140,000-route-mile network of track outfitted with PTC and be operational by December 31, 2015. Unless, subsequent to its enactment, this mandate has been amended, that is the deadline. Prompting the legislation was a 2008 head-on collision between a freight train and passenger train in Chatsworth, California; a crash that claimed 25 lives and left scores injured. It was one of the worst train-to-train collisions in modern times.
- “Quantification of the Business Benefits of Positive Train Control,” prepared for the Federal Railroad Administration by ZETA-TECH Associates, Inc., rev. Mar. 15, 2004, “APPENDIX A: Acronyms and Abbreviations,” p. 128.
- Ibid, p. 58: (“IV. PTC B Benefits,” A. Line Capacity)
- Ibid, p. 60: (“IV. PTC B Benefits,” A. Line Capacity: “2. Cost of Increasing Capacity”)
- Ibid, p. 57: (“IV. PTC B Benefits,” A. Line Capacity)