Yeah I think that this plant is what I would call “Semi-Automatic” in function; it won’t auto clear unless the movement was requested. If a request is locked out due to a prior request or conflicting occupancy the locking condition clearly has the highest priority, being a “vital” interlocking function. I do wonder, however, if requests are “stacked” to become effective after all locks are cleared.
Movements out of G3, departures or shifts, seem to proceed without regard to a clear at the diamond; they just proceed as permitted by the plant, just like other, trough movements. As for the dispatcher coordination, I have no definite idea, nor do I have any sense of any formal agreement that may govern prioritiy of movement; it really seems to be first grab, first through (enforced by the timeout feature to prevent excessively advanced requests). I regularly seen high priority intermodals ( Z trains) delayed f
If either or both carriers have to ‘request’ a route through the plant, it is not truly a ‘automatic’ crossing - wherein, just the track occupancy of a train automatically requests the signal.
With Global 3 being immediatly West of the crossing, it would be in the UP’s best interests to be able to use the WB signals over the crossing as ‘hold out’ signals to allow Global 3 crews ‘head room’ out of Global 3 down to the diamond. I have always suspected that the crossing was ‘semi-automatic’ where either carriers Dispatchers had to request a route through the crossing before the ‘automatic’ circuitry would become effective. It would be interesting to know what level of ‘land line’ communications take place between the UP & BNSF Dispatchers in lining up traffic over the crossing.
Yeah I think that this plant is what I would call “Semi-Automatic” in function; it won’t auto clear unless the movement was requested. If a request is locked out due to a prior request or conflicting occupancy the locking condition clearly has the highest priority, being a “vital” interlocking function. I do wonder, however, if requests are “stacked” to become effective after all locks are cleared.
Movements out of G3, departures or shifts, seem to proceed without regard to a clear at the diamond; they just proceed as permitted by the plant, just like other, trough movements. As for the dispatcher coordination, I have no definite idea, nor do I have any sense of any formal agreement that may govern p
Hi-Rails don’t shunt at all - not even highway crossings. They have to “stop, look, and listen” at any crossing - rail or road.
Back in TT&TO days, they knew when they had to be clear. Nowadays, they’ll have a track warrant/Form D/EC-1, or whatever method the railroad uses to grant exclusive use of the track. Most I hear on CSX include a time component (“until 1600…”).
If you look at the ICC accident reports for the first 75 years of the 20th century, it seem as though at least 20% of the reported accidents (and even more of the incidents involving fatalities) involved MOW crews colliding with trains. The old way doesn’t seem to have worked very well - treating MOW/Inspectors as a “full-fledged train” was long overdue.
MofW are not treated as a train and have no authority to pass absolute signals, operate switches or occupy Main or other signaled tracks without the formal written permission of the Train Dispatcher that grants them exclusive use of the track segments requested. MofW equipment, hi-rails or otherwise is not governened by the activation of track circuits, even when the equipment does activate track circuits.
In days of yore, MofW operated on ‘Track Car Line Ups’ that were issued by the train dispatcher and identified the trains on the territory, their location and their relative operating ability - Scheduled trains were identified and timed by their schedules. Very easy for mistakes to be made by everyone involved - thus the carnage.
In the US it is a term for completing the electrical track circuit between the rails. As with many words in the English language, the same word can have multiple meanings depending upon the context in which it is used.
Do you understand how a basic track circuit works on US railroads? (A battery keeps a distant relay closed with the rails between the battery and the relay carrying the electricity.) The wheels of locomotives and cars on the track between the battery and the relay allow the current to pass from one rail to the other without passing through the relay. The relay, being without power, opens and the train has been detected. You could say the power was ‘shunted’ around the relay. I’ve more frequently heard the term ‘shorted’ to describe this.
Out here, use of shunts is limited, usually in a few key hi-rails belonging to operating officials*. They have a penchant for wearing out the brushes (rail contacts/ “shunts”) and the small pneumatic cylinders. MOW Hi-rails are created and thought of as work equipment. As such they have to flag crossings, prepared to stop (They can become liable, even if the moron motorist circumvents the gates & signals. Rules differ slightly between states.)
A few track supervisors/ motor track inspectors have hi-rails with shunts in congested areas, but the hi-rail operator using them is well aware of pumping gates and interaction problems (ie - don’t put a whole lot of faith in your Fairmont/Mitchell/ whatever gear around crossings. Boy Scout Motto applies!)
some of them are true knuckleheads that exceed (greatly) the rated speed for the hi-rail gear, forget about the relatively small flange of the wheels, are hard on bearings and hard rubber wheel coatings (tire/tread) and generally are a menace to the equipment. I’ve seen what happens to an ex-Trainmaster’s Bronco Hi-rail when he derailed it at 60+ MPH on the Transcon.
Penn Central didn’t use shunts like these; at least, not while I worked in that area in Pittsburgh (1970-1972 or thereabouts). We didn’t have the “knuckleheads” you described, either. (Of course, we didn’t have the wide open spaces either; I am still a little uneasy at the sight of straight level track as far as I can see. [;)])
My biggest problem was signal maintainers or track supervisors, who normally rode alone, insisting that they needed a 6-man crew cab.
I have pictures of former Track Inspector’s truck - 20 feet up in trees, with 3 rail wheels on the truck and the high side front rail wheel broken and on the right of way. He was found by river rafters and the former Track Inspector had to be Life Flighted to the hospital after the rafters transported him a mile or so downstream to a point where the Life Flight could land. Bozo’s have no craft distinction.
I watched as these equipment came from the west, then started at the diamonds, and worked back to the west. For a while a six or seven were on the East side of the diamonds, and slowly, one by one, they returned across the diamonds and worked west. about 1500 they dissapeared from view around the curve. I’ll try and get the pictures i’ve taken all day and post them in sequence. I don’t know when all the trucks dissapeared, I was away about an hour. at 1600 they were all gone.