Let’s say a freight train is running at 10mph (uphill grade) and a second train is following behind. I dont know for sure, but the assumption would be a “restricted” aspect and rule.
What distance should the second train follow the first? The rule indicates be able to stop 1/2 the visible distance.
Would 14 seconds be sufficient distance to follow? At 10mph the trains are running at 14 ft per second. Would the second train be able to stop within 100 ft? (based on 14 ft per second x 7 seconds). Would it matter that the second train is a passenger train.
I know I’ve seen at least two film records that show a train following another with very short headway – I estimated not more than about 30-40 feet, certainly much less than one ‘locomotive length’.
Both were in curving, mountain territory. I presumed the train crews were in radio contact with each other, although I can think of multiple conditions that would make so little following distance ‘inadequate’ for restricted speed.
As I recall, both following trains were passenger trains. I would expect this because you’d need true graduated release of the air brake, and ‘proportional’ response from independent and dynamic might not hold a freight consist in time to prevent contact.
I’ll admit that both times I thought the practice irresponsible as hell, although I also admit that having the back end of a train moving at presumably ‘restricted speed’ range continuously visible would be better in some respects than having it come in and out of view on curves.
I try to avoid having to run at restricted speed. Unless there’s a good reason to do so, I’ll stop if I need to so I can control where we stop. Otherwise I may have to stop on crossings or where the terrain can be “challenging” to start up again.
PTC helps now somewhat because you can see in-between signals how the train is doing. Once you’re in the restricted speed zone, PTC is useless. It doesn’t know where the end of the train ahead is.
A service air brake application moves at 540 feet per second. You have to allow a few more seconds for each car’s brakes to set up. If you’re going uphill you’re not going to want to use dynamics. If I’m going to have to follow someone on a restricting going up hill where sight distance is severely restricted, I’ll be running at a speed where just dropping a throttle notch or two alone will bring me to a stop.
I’m not going to follow a moving train close enough to read the fine print on the EOT.
In a ‘fluid’ railroad - trains will wait to get at least an approach signal when they know they are following a moving train. If they come across a restricting and they have been following a train on Approach’s they will try to make contact with the preceding train to ascertain what is going on and then make a decision on what to do - notifying the Train Dispatcher of what they are going to do and why.
With the size trains being run in the 21st Century - trying to ‘cheat’ on 1/2 the range of vision is a invitation to disaster.
It’s possible that the passenger trains WH was referring to had electropneumatic braking where the response would be close to instantaneous. While I have never had the experience of being the engineer on a freight train, I can fully understand why you would not want to be close to a train you are following.
Back in the day - with closely scheduled passenger trains it was common practice to ‘ride the Approach’ with the expectation that the signal would change to Clear BEFORE the train passed it.
In most rule books, an Approach Signal requires the train getting it to reduce speed to Medium Speed upon observing the signal and to approach the NEXT signal prepared to STOP. Many more than one rear end collisions happened with trains ‘riding the Approach’ approached that next signal at a speed they could not stop without passing the signal - and there just beyond the signal was the STOPPED train ahead.
Back in the day - nominal signal spacing was one mile. In the 21st Century signal spacing is nominally between two and three miles because of the stopping distances for trains using non-emergency brake applications.
I’ve come across several references to that happening along with you making numerous and very true comments that railroad safety can not rely on “line of sight” visibility. What Woke was mentioning is that by keeping the train ahead in sight at all times, the engineer of the following train will be continuously aware of the speed of the train ahead - still pretty dicey.
I just saw an article about the 1972 IC commuter wreck the other day. For those unaware a new lightweight double decker high liner missed a stop and decided to back up. The following train was a heavyweight old single decker.
The trains were scheduled close together so the following engineer was used to riding the yellow. This time he got unlucky. Hit the new train at almost full speed. The old train telescoped into the new train which was not only higher but also wider. 45 people died.
It could have been worse. Accident occurred next to Michael Reese Hospital. Doctors and nurses were treating the injured while still in the wreck.
Keep in mind, though, that the emergency brake signal propagates at close to the speed of sound in compressed air – about 9800 feet per second.
Which is why the great ECP mandate of the mid-2010s fell apart so badly. The superiority of ECP for service braking is astounding even before you appreciate graduated release, and I am hopeful at some point that incentives to build and maintain ‘convertible’ equipment are made. However, Feinberg & Co. phrased it as a safety concern, for key trains/exploding crude oil trans/PIH trains… and in any such situation, the automatic would be in emergency.
Now calculate the time it takes for all the emergency brake valves to open at ‘electrical current’ speed vs. that 9800fps. Now factor in what happens if the FRED can dump to pulse emergency at the back end. The rest of the emergency set proceeds at essentially the same speed, and this is where the ~3% quicker emergency-brake application and shorter stopping distances come from. Apparently no one in the Government bothered to distinguish this, so we had the promise of an unfundrd mandate for north of $2.3 trillion for… 3% shorter best-case stop with all the risks and pitfalls of an emergency set anyway.
I think that was the cause of the Burlington rear end collision in 1946. railroad’s Exposition Flyer rammed into the Advance Flyer which had made an unscheduled stop to check its running gear. The Exposition Flyer had been coming through on the same track at 80 miles per hour (130 km/h). There were 45 deaths and some 125 injuries.
That’s a nice part of running in NORAC “Form D” (ie, track warrant, etc) territory - no signals.
That said, we have situations where we need to run a second train behind the first. Since communications with the dispatcher aren’t the greatest on parts of our line, we have a rule allowing a section of track to be taken out of service - essentially, the person doing so becomes the dispatcher. The first train can run at up to 30 MPH on the OOS track. The following train can then run restricted (up to 20 MPH). Usual practice is for the leading train to call out mileposts, and the following train to stay at least two miles back.
Normally, circumstances put the following train at least two miles out to begin with, and the 30/20 MPH speed difference ensures the following train never catches up, if the leading train proceeds as scheduled.
Once the leading train clears the OOS, the following train can increase to 30 MPH.
One too many zeroes. An emergency application travels more like 980 ft per second.
Back in the 1970s, the newest brake equipment made for a service application to move at 230 feet per second. Now the improved equipment makes for a 540 ft per second service application. It didn’t change the speed of the emergency application.
Your mention of the “corn field meet” (jargon for crash) in Naperville, caused me to research the same. Associated item: Present day (2014), an artist created a three person display made of 5000 spikes. It took 6 months. 1 mile of weld rods. The three depict persons who came from the surrounding area to aid the injured. It is displayed presently in Naperville, IL. endmrw0421251054
So much to research. Regarding crashes. On the West coast an [quote=“charlie_hebdo2, post:11, topic:412456”]
Exposition Flyer
[/quote] was involved in a 1941 crash. The “problem” then was a RR engineer’s watch was 20 minutes SLOW. There are newspaper clippings in the day showing “accident cause pocket watch” and the correct time pocket watch. So sad. Of course in that day TO’s were all based on TIME. Correct time. And as a RR person, your watch had to be ONLY a RR approved model. endmrw0421251010
You may remember in 1891 Webb C. Ball building his empire out of a railroad watch that needed to be 17 jewels or better… look up ‘smokestack jewels’… but soon 19 jewels or better, and keep time to better than 30 seconds a week.
And the employee was forbidden to set the watch himself. Only a jeweler employed by the railroad time service could open it, either to adjust it or set it, which was mandatory once a week. So the watch could never be out more than 30 seconds…
The ‘five positions’ come into railroad service because of how the pocket watch could be carried. A dress watch only needs 3 positions, because it’s stored at night either dial up or dial down, and only ever pocket-carried bow up (in pants or jacket). A working engineman might have the bow tipped to the left or right, hence 5 total. Adjusting to positions makes the watch timing more regular (specifically makes the arc of the balance equal whichever way the watch is held) for better precision.
There was no excuse for a watch running 20 minutes late that should have been out of the engineman’s control.
Jeff, I thought the ‘improvement’ was that the valve in the FRED would move proportionally with a set to vent air from the rear of the trainline forward, and that’s where the ‘faster speed’ came from. It’s really ‘half the time’ and not faster application from front down the trainline to the rear, right?
AFAIK, Fred only vents air when the emergency feature is activated. I believe the faster reaction time is due to better control valves and enhanced features. The brake equipment on the cars, I believe, also can vent a small amount to speed up the propagation.
I don’t know when, but a sixth position was added to the requirement. Before they loosened the requirements, some railroads allowed an 18 jewel or better, others 21 jewel or better. Now a watch only needs to be “reliable”. A watch still needs to be within 30 seconds of the time standard.
The period between inspections for a pocket watch also changed. The last requirement was inspected, cleaned and oiled every 48 months.
The rules had a small safety factor in that opposing inferior trains were to clear superior trains by 5 minutes. Some timetables, when the streamliners started appearing, required inferior trains to clear by 10 minutes.
My understanding of brake valves on the cars is that if they sense an emergency application, they also dump, which speeds the full application as it clears the air from the brake pipe.
Which is pretty easy to with a relatively decent electronic watch - I remember Timex “Ironman” watches easily keeping time within 30 seconds over a course of a month back in the early 1990’s. Time checking was done by listening to WWV.
