Anybody tried DCC and went back to DC?

Fat chance - he'll be too busy shagging sheep.

At any rate, now you can have the pleasure of trying to persuade the boneheaded bastard that the German way is not the only way...

Because otherwise, eventually a train behind will catch up to the one in front, with potentially catastrophic consequences. Writing "Rule 25.7.1 The train behind must not catch up with the one ahead." or "Rule 17a: the train ahead must not lose time or stop while ahead of the one behind." will NOT keep trains apart.

Because you can't

Because I can't conceive of a written rule that will allow two trains to run on a single track section that will keep them apart under all circumstances.

That's pretty much it! The train following the rules must vacate the section, so in effect there are not two trains in the section. The rule doesn't make anything safe but following the rule should make the action safe.

The correct orders and correct rules wouldn't help if the leading trainwas slowed by, for example a brake hose failure or a hot box. There needs to be another safeguard available.

There's the additional safeguard! Trust Mark to miss the blindingly obvious!

Which makes it quite a bit safer in actual practice than in the

That's great in principle, but the conductor has to be able to run further than the following train's braking distance in the time he has available, which, if his train has slowly lost speed, could be a very short space of time. Many accidents happen when there are two (or more) conflicting errors made and sometimes errors which are only recognised in hindsight.

Here in New Zealand we have only half the population density of the USa. I haven't compared mileage to population but it's likely we have an even worse ratio than you. We have some very long stretches where ATC/signalling isn't cost effective so TO/TT running is the norm. with it goes radio communication _and_ GPS with GPS position reporting to the dispatcher. He/she can see on screen where the trains he controls are and communicate with the relevant drivers.

I'm not going until I've finished all my projects!

Regards, Greg.P.

It also showed some of the shortcomings of the systems.

I work for Babcock & Wilcox Vølund in Denmark. We design and construct waste-fired steam boilers for the Eurepean marked. I work with the design of secondary systems and control & monitoring systems. Have a look at our web page

When the normal feed water supply fails, even on waste-fired plants we have a back-up, either an emergency diesel-driven generator supplying power to a feed water pump, or a dedicated feed water pump driven by a steam turbine.

We always have physical end position switches on controlled valves in the steam and water systems, the switches are hard-wired to the control & monitoring system.

As for safety relief valves, normally they will close when the pressure drops below the set pressure limit but this is not monitored as it is a very rare occurence. Normally it is not a problem as the blow-off is rather noisy and can be heard from the control room. A more probable fault with such valves is that the valve closes but is leaking. We have no way of detecting this automatically, this is why such valves must be checked visually by the operator after a blow-off.

You really don't know that yet. The people working on the plant received the highest radiation doses. If some of them die from cancer 40+ years after the incident, this may be caused by the exposure.

I guess that line shows us all exactly the level you're at.

Go back to the subject line - my specific prototype has a form of operation which I found easier to emulate with DC, after trying DCC. The German way is the only way _for my layout_. I've never claimed anything different.

Now, eh?

"In order to prevent that pressure from becoming excessive, the pilot-operated relief valve (a valve located at the top of the pressurizer) opened. The valve should have closed when the pressure decreased by a certain amount, but it did not. Signals available to the operator failed to show that the valve was still open. As a result, cooling water poured out of the stuck-open valve and caused the core of the reactor to overheat."

- from the NRC Fact Sheet on TMI:

At least my uncle could see when safety valves popped on his NKP Berkshire

*, but at TMI even if they could have seen it they couldn't get near it.

• mandatory RR content

in article 81fc3$44faa17c$3e3d8433$ snipped-for-privacy@news.arrownet.dk, Erik Olsen at snipped-for-privacy@hotmail.invalid wrote on 9/3/06 2:34 AM:

No studies to day, including the lawsuit have determined that the radiation exposure has caused any problems, or was severe enough to have caused problems. The cancer rate in the three mile island area and among the workers is within normal ranges.

So, you may be right that there are still some lingering issues awaiting discovery, but there are zero facts supporting that, so it is only speculation.

It is not speculation that the use of coal fired plants instead of nuclear plants in the US and world wide has increase CO2 emissions, and through the release of various particulate which are mildly radioactive (pitch blend, after all, is the substance from which radium was initially isolated) and have contributed to vastly more illnesses, including cancers, than a like generating capacity from fission plants would have caused, barring a Chernoble like accident. Frances experience is noteworthy in this regard.

Of course this inadequate system (Dispatcher + Time Table + Train Orders) was used quite successfully for over 50 years.

If a train is stopped on the main it must send out a flag man to the front and read to protect itself. When the flag man is called in he leaves detonators on the rail to warn any following train that there 'was' a stopped train ahead.

If the train is moving but behind schedule and in danger of being overrun, the conductor in the caboose drops lit fuzees of the back of the train at five minute intervals. The fuzees are designed to burn for five minutes. Any train approaching a lit fuzee is required to Stop and wait until it has burned out, then they may proceed at a restricted speed.

Full interlocked signaling is fine for those small areas that have the traffic to justify the expense, but in the many 10s of thousands of miles of trackage in North America outside of those signaled areas, Time-Table and Train Order worked very well. That is why it lasted so long. It did require intelligent crews able to read and understand the time table and who were conversant with the current rule book. That is why all crew members were tested on the rules.

Only in current times has the cost of technology dropped to the point that it is economical to fully signal 'most' of North America.

Bill Dixon

"Greg.P." wrote in news:edi6r5$7h8$ snipped-for-privacy@lust.ihug.co.nz:

True. It creates a somewhat greater risk than separating trains totally by ATC. But the risk was deemed acceptable by the people whose lives and fortunes depended on it.

This *is* the way a lot of prototypes did it. What *modelling* purpose does it serve to discuss whether they should have done it this way ?

And of course - even ATC cannot guarantee that you won't have accidents. In the area of Norway where I live, all lines and most trains have ATC and most trains are electrical (so you can cut the juice in the overhead catenary).

We still get accidents. A few years ago a freight train lost its brakes coming down a steep hill, rolled past several red signals and hit a parked train, knocking a hole in a propane tank car, starting a major fire in the middle of a city in the middle of the night and caused a situation where we had to evacuate several thousand people (it was feared that the burning tank car could cause a massive explosion). It disrupted rail and other transport on the east of Oslo for four or five days until the danger was over. Human error, I think it was - brakes misconfigured, and not testet properly until it was too late - in a steep downhill.

No system devised by human beings can totally prevent human beings from making errors. In my line of business (computers) the rule of thumb is : "you cannot really make anything *totally* fool proof. The fools are too smart for that - they will come up with something new so stupid nobody has ever thought about how to prevent it"

Grin, Stein

The simple answer is not to keep on using/requiring more and more power, but to make your usage of energy more efficient. The US uses twice the energy per capita than other comparable nations.

Regards, Greg.P.

"Successful" is very subjective - how many crashes are acceptable while still regarding the system as successful? The system cannot guarentee to keep trains separated in normal usage, let alone fail safe or cope with normal human oversights or failures.

That leaves a window of danger while the flagman walks the breaking distance (plus a safety margin) of the following train.

That assumes the following train cannot cover the five minute distance in five minutes - another gap in the theory!

The fuzees are designed to burn for

Ok, our troubled train is moving at 12mph while the following train is moving at 60mph. Fusee thrown, at milepost (say 100) train moves forward 4/5 mile in the next four minutes. The following train is 5 minutes behind and arrives at the fusee as it goes out. At minute #5 at milepost #101 the first train passes, the conductor lights his second fusee and the express arrives at 60mph. Crunch!

You gave two examples of rules and I've shown you where they fail.

My somewhat laboured point is that allowing two trains into a single uncontrolled block/section/call it whatever of track creates a danger of collision that can't be covered by a rule book.

Regards, Greg.P.

Sure, but the rest of the world runs passenger trains.

I don't know - it wasn't me who determinedly took the thread away from the subject line.

Very true, but there's a difference between "failsafe" and deliberately putting trains in situations where the only safety margin is a variable time separation.

In my line of business (computers) the rule of thumb is :

Sure, but computer programs normally don't run into propane tankers.

The first time I applied a computer to operate my model railway, I put point/passing detection on the mainline so that the train was detected leaving the station and again entering the staging yard. It worked very well until the day a friend brought around his brand new very prized loco. He placed it on the nearest stretch of mainline while I crawled under the layout to turn the power on. The computer powered on, read no conflict, and sent the next train from staging yard to station. I crawled out just in time to see my prized express loco run head on into my friend's new loco!

You're wasting your time, Bill. Procter - the Vicky Pollard of r.m.r. - will never concede that TT/TO was used successfully throughout the USA for mnay years. His knowledge of these matters is far greater than yours

- he once had a friend who spoke to someone who had a friend who travelled by train once - so he speaks with authority when he says it can't work...

The risk is not just covered by a rule book. There is the train crew, the operators, and the dispatcher, all operating in concert with the timetable, the rulebook, clearance forms and train orders. As usual, you distort the situation to suit your argument.

So did the North American railroads, using TT/TO working. Historical fact - which you'll no doubt dispute...

Don't be such a disingenuous prick, Procter. You were quite happy to bang on about prototype operating rules and procedures when it suited you - when you thought it gave your arguments credibility.

And this is the prototype-inspired system you claim is superior to DCC?

Hahahahahahahahahahhaha!!!

Well, that's the first sensible thing you've written in this thread. You, sitting in your bach in New Zealand, running and pranging your models with a computer, think it's unacceptable. The North American railroads, in the real world, running real trains with real people, disagreed. Get over it!

No system can *guarantee* to keep trains separated in normal usage. Like any sytem, TT/TO worked most of the time. >

You gave two very silly, ill-thought-out hypothetical examples which are not borne out by real-world experience.

Advantage? It's a feature, but I've never seen it called an advantage. More of an "if you really want to" item that the NMRA wrote into the standard and the manufacturers complied with.

I certainly don't recommend address-0 operation on DCC as a good way to run DC locos - mainly because the noise it makes is annoying. That said, in my experience the phenomenon of such operation damaging or destroying motors is not widespread, at least not in HO scale. Besides, I don't think that that cross compatibility with the other system is a reason to buy or to not buy either one in any case.

There are several perfectly valid reas> That's one more reason for discounting that often touted "advantage" of DCC.

I already know - just winding up your clockwork train. =8^)))

Rule books can't keep trains apart when you place two in a single uncontrolled section of track. The train crew can follow the rules but situations can occur when positional conflict occurs within the rules.

I have no interest in dusputing known facts.

They were my argument - _specific_ rules and procedures which made DCC unacceptable to me on my specific layout for my specific mode of operation. I'm not operating some woolly amalgamation of average US operating procedures. That isn't a suggestion that anyone else, other than you, is.

No, it was my first attempt at using a computer to control certain functions of my model railway. I merely recounted a total oversight in my programming.

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