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Positive Train Control - Federal Legislation Pending

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Positive Train Control - Federal Legislation Pending
Posted by Paul_D_North_Jr on Wednesday, September 24, 2008 8:29 AM

Well, since no one else posted it yet (as of a few minutes ago), here goes:

According to many news sources this morning - e.g., the Associated Press, see:

http://ap.google.com/article/ALeqM5gjqjFAWFWvi317oJXvAGReNmEQXAD93CPF6O0

or just search for recent articles on "rail safety" - the U.S. House and Senate have agreed on a bill that mandates that some form of positive train control be installed on most rail lines (just about all of them carry hazardous materials at some time, right ?) by 2015.

One article mentioned that the Feds will provide $50 million to help pay for it.  [If we consider that the U.S. rail network that would be subject to this is probably on the order of 50,000 miles, then that amounts to . . . about $1,000 per mile.  I'm sure that some of our members here - Railway Man, in particular - can comment on how insufficient that will be.]

Also, the Hours of Service law will apparently be amended to reduce the maximum per month from 400 (about 13.3 hours per day average) to 276 (about 9.2 hours per day average).  Didn't see when that will take effect, though.  Those of us interested in train service - get your applications ready !  There's going to be a huge need, I suspect.

More philosophically, this illustrates the kind of thing that can happen when people and institutions delay or postpone too long, and don't "get out in front of" making a needed change or decision.  Something inevitably and unavoidably happens to bring the issue to a head - here, it was the Chatsworth collision, in other contexts it could be weather (hurricanes), markets (financial meltdowns), competition, attacks, old age (nursing home), etc. - and the change or choice happens by force of some kind, not voluntarily.  Is this really the outcome that the rail industry wanted, and the way it was desired to come about ?  Wouldn't a voluntary implementation of some kind - with all of its attendant problems - have been better than this ?  So now what did the industry gain by procrastinating so long on this issue, and now having it forced down their throats by a couple of political demagogues ?  (Boxer and Feinstein definitely have that game nailed)  Once again, the industry is dragged kicking and screaming into the current century.  Something to think about and keep in mind for other future issues.

Responses - challenges, further thoughts, questions, comments, criticisms, suggestions, etc. anyone ?

- Paul North.

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Posted by route_rock on Wednesday, September 24, 2008 12:41 PM

  ETMS is the only kind of PTC I have seen and its not 100%. Its still being tested and let me say one word to you. Lobbyist.2015? Ok thats 7 years away, will you remeber that this legislation is in play? What if its tabled to commitee? and never allowed back to see the light of day?

  Hours of service will never change unless its done right away. No BS debates, no " We need a commision to look in on this"or Table for further debate.Remember the one word I stated. In an older copy of mt BLET newsletter UP engineers, rank and file guys, were going NUTS about losing hours!!! Of course thats not all of us. I am all for sensible and sane working conditions.I am not one who likes to be a zombie or work with one.12 hours on and then 8 hours later your back at it. I know Mr Rose is not happy with crews over 12 hours and all the limbo time thats been racking up. Hes afraid of being told we can only work 10 hours and then off 10. Dear god he says, I will have to hire more people!! So guess whos lobbying this not to go into effect?You got it! The same people who are saying " We are worried about fatigue as well" sure they are. only been worried about it since steam days and still cant find a solution.

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Posted by jeaton on Wednesday, September 24, 2008 2:46 PM

With regard to PTC, if you look at the link shown below, you will see that the FRA, the very government entity that should be leading the way to get a safe PTC system in place has actually done nothing in the way of research and development themselves, or providing any financial support for R&D efforts.

Instead, the FRA has said, in thousands and thousands of words to the effect, "You can develope and install processor based PTC systems on your own dime after you prove beyond any doubt that the system as and where installed will never fail.  Also, if you don't follow our rules and provide all the necessary documentation, we will slap you with civil fines per the attached table.

Don't get me wrong.  I am all for these things being reliable and safe, but it seems to me that performing and documenting the development and the testing on installation has to add millions to the cost of the system.  Is it all necessary?  If the system includes a failsafe process where if any part fails, things come to a stop or a slow crawl, is it necessary to guarantee and prove that it will never fail?

I could be totally off base but the whole thing looks like a CYA process, if not obsessive or paranoid.  The FRA won't take any chances that they might take a political hit for allowing something that might fail, and given the potential for fines and perhaps in a worst case, civil or criminal liability,  maybe developer and railroad personnel are reluctant to sign off. 

I don't know exactly how the new US Congressional Safety Bill is structured, but I'll bet it neatly fits in the category of "unfunded mandate".  Sometimes those thing are written as "Do it, or else..." with no "or else" written in the law.

http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=7d8e0068e9bf53874eb8a24dbbf9eb01&rgn=div6&view=text&node=49:4.1.1.1.30.8&idno=49

 

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Posted by Murphy Siding on Wednesday, September 24, 2008 5:12 PM
     To be fair, I'd assume Congress is going to make the trucking industry develop a similar, very expensive system, for the good of the people.Wink [;)]

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Posted by Rodney Beck on Wednesday, September 24, 2008 8:42 PM

Nothing is 100% perfect etms,ats & cab signals systems can and do fail.

 

Rodney

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Posted by greyhounds on Wednesday, September 24, 2008 9:24 PM
 Rodney Beck wrote:

Nothing is 100% perfect etms,ats & cab signals systems can and do fail.

 

Rodney

That be the point.

Write a law/regulation that requires 100% while nothing can be 100% and you create an impossible situtation that ensures nothing much gets done except for your own CYA.

The Federal Government is very good at this.

"By many measures, the U.S. freight rail system is the safest, most efficient and cost effective in the world." - Federal Railroad Administration, October, 2009. I'm just your average, everyday, uncivilized howling "anti-government" critic of mass government expenditures for "High Speed Rail" in the US. And I'm gosh darn proud of that.
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Posted by tree68 on Wednesday, September 24, 2008 10:39 PM

 Murphy Siding wrote:
     To be fair, I'd assume Congress is going to make the trucking industry develop a similar, very expensive system, for the good of the people.Wink [;)]

Even better, tie it into the traffic signal system so if a truck is approaching a red light or a stop sign, it will automatically slow down....Evil [}:)]

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Posted by oltmannd on Thursday, September 25, 2008 11:43 AM

I really don't get those changes to the hours of service laws. They fix the wrong thing!

The big problem is the unpredictability of call times and having guys work "against" their circadian rhythems.  You call a guy at 7AM today and 7PM tomorrow, you're fighting biology.  It is the huge "elephant in the room" that nobody's been willing to do much about.  Instead, they nibble around the edges.  A few more "show up" jobs.  A few districts with carded pools.  10 hrs rest at home terminals.  But nothing that actually fixes the problem.

Limiting the hrs per month won't do it either. It may be a good solution for the airlines - who don't recrew en route - but for the RRs, it fixes nothing.   It'll just make the pools bigger and adds to the away from home time and/or more deadheading.

I also don't get the concern about fatigue for the Metrolink engr who was working regular split shifts - and probably had regular days off.  What about the frt pool guy who gets called at 10AM, then 3PM, then 7PM, then 2AM.  He doesn't stand a chance of being at his best.  Working 5AM to 9PM, M-F,  with 4+hrs off for a nap mid day (including a place to take a nap and get a meal) pales in comparison....

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Posted by BaltACD on Thursday, September 25, 2008 12:24 PM

Total Congressional CYA .... and these same loons are involved with the financial crisis?

Where is the :vomit: emoticon?

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Posted by Paul_D_North_Jr on Thursday, September 25, 2008 2:20 PM

Well, the AAR evidently thinks that this bill has passed or is about to pass - see below, from its website at:

http://www.aar.org/Pressroom/PressReleases/2008/09/092408_Statement_on_railsafety_bill.aspx

However, other reports say that it is doubtful that the Senate will be able to concur in the conference committee's compromises by the anticipated recess at the end of this week for election campaigning - that shows us what's really most important, doesn't it ?

-------------------------------------------------------------------------------------------

Statement by
Edward R. Hamberger, President and CEO
Association of American Railroads
On Passage of the Comprehensive Rail Safety Bill
 

Freight Railroads Commend Congressional Leadership on New Rail Safety Bill

WASHINGTON, September 24, 2008 - The railroad industry would like to commend the leadership of the Senate Commerce Committee and the House Transportation and Infrastructure Committee for the work they did in crafting a comprehensive and far-reaching rail safety bill.

Nothing is more important to the railroad industry than the safety of our employees and the communities we serve. Although 2007 was the industry's safest year in history, we recognize that there is always room for improvement. Provisions of the new safety legislation will help facilitate even more improvements in safety.

The legislation sets an aggressive deadline of 2015 for implementation of positive train control (PTC) across most of the rail network. The scope of the work remaining to be accomplished presents a challenge to both the supply industry and the railroads.

Nonetheless, the freight railroad industry is committed to doing everything it can to ensure that PTC is implemented effectively and safely. We will work with the Federal Railroad Administration and our partners in the transit community, at Amtrak, our suppliers and our customers to implement the mandate.

-------------------------------------------------------------------------------------------

"This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Posted by trainfan1221 on Thursday, September 25, 2008 2:31 PM
 tree68 wrote:

 Murphy Siding wrote:
     To be fair, I'd assume Congress is going to make the trucking industry develop a similar, very expensive system, for the good of the people.Wink [;)]

Even better, tie it into the traffic signal system so if a truck is approaching a red light or a stop sign, it will automatically slow down....Evil [}:)]

Ya know, that just might work..
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Posted by Last Chance on Thursday, September 25, 2008 4:24 PM
 trainfan1221 wrote:
 tree68 wrote:

 Murphy Siding wrote:
     To be fair, I'd assume Congress is going to make the trucking industry develop a similar, very expensive system, for the good of the people.Wink [;)]

Even better, tie it into the traffic signal system so if a truck is approaching a red light or a stop sign, it will automatically slow down....Evil [}:)]

Ya know, that just might work..

 

No it will not. Not with all the random oppertunities for accidents, damage or other problems on approach, passage and leaving said intersection.

That robot truck will mash granny trying to catch a bus and it will not hear the screams. Or in certain parts of the north east give a bad person an oppertunity to jump onto the catwalk and slice the left hand airhose to steal the cargo.

I for one refuse to accept totally automatic vehicles unless they are absolutely seperated by any possible interaction with anything. Either 40 feet into the sky on a dedicated track or buried 50 feet or more below.

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Posted by BaltACD on Thursday, September 25, 2008 4:47 PM
 tree68 wrote:

 Murphy Siding wrote:
     To be fair, I'd assume Congress is going to make the trucking industry develop a similar, very expensive system, for the good of the people.Wink [;)]

Even better, tie it into the traffic signal system so if a truck is approaching a red light or a stop sign, it will automatically slow down....Evil [}:)]

And where they have installed 'Red Light Cameras' the incidence of rear end collisions has increased to levels far above any 'running the red' incidents that had occured at the intersections....be careful of what you ask for....you may get it...IN SPADES!

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Posted by Paul_D_North_Jr on Thursday, September 25, 2008 5:34 PM

On the other hand, "This just in:" - from about an hour ago:

"Legislation that would mandate collision-avoidance systems for trains and boost funding for passenger rail service is being blocked by Republican Sen. Tom Coburn of Oklahoma, one of the Senate's leading fiscal hawks."

For all the details, see: http://online.wsj.com/article/SB122237337593376137.html?mod=googlenews_wsj

For more on Sen. Frank Lautenberg's (N.J. - D) several pro-Amtrak and other railroad bills and provisions, see the "Bottleneck Blog" on the Los Angeles Times website at:

 http://latimesblogs.latimes.com/bottleneck/2008/09/rail-safety-bil.html

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Posted by jeaton on Friday, September 26, 2008 5:37 PM

Dennis Duffy, UP's EVP Operations testified at the 9/23 Senate Hearing on the subject.  The link is to his prepared remarks.  I think he is clear about the state of the technology and the hangups to rollout.

http://www.uprr.com/newsinfo/attachments/media_kit/ptc/duffy.pdf

 

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Posted by oltmannd on Friday, September 26, 2008 6:12 PM

He managed to say almost nothing while making it sound like a lot. 

Some thoughts:

Stopping to short (outside of dangerous train handling) has safety implications. - Really?  Might not be best operationally, but can't possibly be unsafe.

Commuter locos not modern enought for PTC.  - Really?  What, no electronic air brake?  Lots of frt locos running around without it, too.  Commuter locos could probably get by with a much cruder method of predictive braking because train handling and train consist variables are much simpler.

All trials to date unsuccessful, but have hope for 3rd gen.  - Why?  And by the way, exactly what went wrong in trial #2.  (predictive braking mentioned as problem in trial #1)

I wonder if PTC wouldn't be a whole lot simpler if we had electronic air brakes.  The money paid out for the NS-CSX-CR deal would have equipped the whole US fleet with that!

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Posted by route_rock on Friday, September 26, 2008 6:22 PM

  Horse manure on the older locos. I had an SD40-2 with ETMS on it, and its older than that commuter loco. Whatever is all I have to say. When BNSF said the FRA says ETMS is great and loves it to try and get the unions scared into one man crew talks the FRA kindly told Mr Rose." We never siad that and dont EVER say we support something when we dont" HA HA.

  So far everyone hit the nail on the head, not 100% failsafe. the only place I can see stoppoing too short is bad is on a hill or area where getting a train restarted is going to cause problems.

  But stopping short? It is better to stop short and look like a fool then to go long and remove all doubt .

Yes we are on time but this is yesterdays train

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Posted by alphas on Friday, September 26, 2008 10:04 PM

I read the wsj link and it looks to me that Senator Coburn doesn't have any problem with the safety aspects.  He just doesn't buy into the increased Amtrak funding and all the Federal funding going to DC Metro attached to the legislation.   I suspect most of the voters in OK will have no problem with his stance.   Anyway, if the railroad safety legislation is that important, then seperate it out and it will pass in days.

Given the current financial shape of the country, probably all of our senators and congressmen/women would be wise to hold off on any new funding that isn't absolutely needed right now.  And maybe if there were more elected fiscal hawks in DC the country wouldn't be having both its current problems as well as its tremendous long-term unfunded liabilities (SS, Medicare, Medicade, etc).     

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Posted by Railway Man on Friday, September 26, 2008 10:56 PM
 oltmannd wrote:

I wonder if PTC wouldn't be a whole lot simpler if we had electronic air brakes. 

Technically speaking?  It makes absolutely no difference at all.  You have to configure for the worst-case braking distance anyway, just like you do in traditional wayside signal design.

RWM

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Posted by Paul_D_North_Jr on Thursday, October 2, 2008 2:47 PM

This just in - and a big Thanks ! to "DMUinCT" for mentioning it elsewhere in the "Tonight's Senate Bailout Bill Contains Railroad Trackage Language" thread earlier this afternoon at 1:26 PM, which tipped me off to look for this:

"Senate OKs Rail Safety Bill That Includes Anticollision Measures"

From the Los Angeles Times "BOTTLENECK BLOG" today, at:

http://latimesblogs.latimes.com/bottleneck/2008/10/news-flash-a-ra.html

NEWS FLASH: A rail safety bill that would mandate that passenger trains and some freight trains be equipped with sophisticated systems by 2015 to prevent collisions was approved by the U.S. Senate on a 74 to 24 vote in Washington D.C. on Wednesday evening. The bill passed the House of Representatives last week and supporters believe the margins in both houses make it veto-proof. [emphasis added]  The bill also provides more than $12 billion in funding to Amtrak over the next four-plus years. The Bush administration has expressed reservations over that aspect of the bill.

--Steve Hymon

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Posted by beaulieu on Thursday, October 2, 2008 4:35 PM

Regarding the use of GPS as part of any PTC system, may I suggest reading this article.

 

GPS Spoofing

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Posted by oltmannd on Thursday, October 2, 2008 4:51 PM
 Railway Man wrote:
 oltmannd wrote:

I wonder if PTC wouldn't be a whole lot simpler if we had electronic air brakes. 

Technically speaking?  It makes absolutely no difference at all.  You have to configure for the worst-case braking distance anyway, just like you do in traditional wayside signal design.

RWM

Well, one of the UP's excuses was that the predictive breaking algorithms were too difficult to get the train to stop where you need it stopped.  I remember CP (or was it CN) wringing their hand over the same thing during the ATCS spec days.  It's not really a safety thing, but you might wind up creeping at very very low speed for quite a distance to get train tucked into a siding.  Now, you can wheel right up to the signal at the end of the siding.  Even with cab signal, you get restricting from the cut point up to the signal.

Prediction of stopping distance with ECP would involve fewer variables and should produce less variation in stopping distances.

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Posted by oltmannd on Thursday, October 2, 2008 4:54 PM
 beaulieu wrote:

Regarding the use of GPS as part of any PTC system, may I suggest reading this article.

 

GPS Spoofing

I would hope that any PTC system would include track transpoders and dead reckoning on top of GPS.

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Posted by Railway Man on Thursday, October 2, 2008 7:22 PM
 oltmannd wrote:
 beaulieu wrote:

Regarding the use of GPS as part of any PTC system, may I suggest reading this article.

 

GPS Spoofing

I would hope that any PTC system would include track transpoders and dead reckoning on top of GPS.

I can't speak for every architecture and manufacturer, but the systems we installed include all three.

RWM

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Posted by Railway Man on Thursday, October 2, 2008 7:26 PM
 oltmannd wrote:
 Railway Man wrote:
 oltmannd wrote:

I wonder if PTC wouldn't be a whole lot simpler if we had electronic air brakes. 

Technically speaking?  It makes absolutely no difference at all.  You have to configure for the worst-case braking distance anyway, just like you do in traditional wayside signal design.

RWM

Well, one of the UP's excuses was that the predictive breaking algorithms were too difficult to get the train to stop where you need it stopped.  I remember CP (or was it CN) wringing their hand over the same thing during the ATCS spec days.  It's not really a safety thing, but you might wind up creeping at very very low speed for quite a distance to get train tucked into a siding.  Now, you can wheel right up to the signal at the end of the siding.  Even with cab signal, you get restricting from the cut point up to the signal.

Prediction of stopping distance with ECP would involve fewer variables and should produce less variation in stopping distances.

Track transponders and wheel revolution counters resolve this issue.

RWM

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Posted by oltmannd on Thursday, October 2, 2008 9:17 PM
 Railway Man wrote:
 oltmannd wrote:
 Railway Man wrote:
 oltmannd wrote:

I wonder if PTC wouldn't be a whole lot simpler if we had electronic air brakes. 

Technically speaking?  It makes absolutely no difference at all.  You have to configure for the worst-case braking distance anyway, just like you do in traditional wayside signal design.

RWM

Well, one of the UP's excuses was that the predictive breaking algorithms were too difficult to get the train to stop where you need it stopped.  I remember CP (or was it CN) wringing their hand over the same thing during the ATCS spec days.  It's not really a safety thing, but you might wind up creeping at very very low speed for quite a distance to get train tucked into a siding.  Now, you can wheel right up to the signal at the end of the siding.  Even with cab signal, you get restricting from the cut point up to the signal.

Prediction of stopping distance with ECP would involve fewer variables and should produce less variation in stopping distances.

Track transponders and wheel revolution counters resolve this issue.

RWM

Can you explain?  Suppose I have a 5500' train that has authority to the end of a 6000' foot siding.  Is there a declining authorized speed, based on distance to the end of the authority?  Enforcement based on "worst case" penatly brake application?

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Posted by Railway Man on Thursday, October 2, 2008 9:59 PM
 oltmannd wrote:
 Railway Man wrote:
 oltmannd wrote:
 Railway Man wrote:
 oltmannd wrote:

I wonder if PTC wouldn't be a whole lot simpler if we had electronic air brakes. 

Technically speaking?  It makes absolutely no difference at all.  You have to configure for the worst-case braking distance anyway, just like you do in traditional wayside signal design.

RWM

Well, one of the UP's excuses was that the predictive breaking algorithms were too difficult to get the train to stop where you need it stopped.  I remember CP (or was it CN) wringing their hand over the same thing during the ATCS spec days.  It's not really a safety thing, but you might wind up creeping at very very low speed for quite a distance to get train tucked into a siding.  Now, you can wheel right up to the signal at the end of the siding.  Even with cab signal, you get restricting from the cut point up to the signal.

Prediction of stopping distance with ECP would involve fewer variables and should produce less variation in stopping distances.

Track transponders and wheel revolution counters resolve this issue.

RWM

Can you explain?  Suppose I have a 5500' train that has authority to the end of a 6000' foot siding.  Is there a declining authorized speed, based on distance to the end of the authority?  Enforcement based on "worst case" penatly brake application?

The system (that I'm familiar with) looks at the braking rate necessary to stop the train short of the "fence", given the speed at which it's traveling, the weight of the train (taken from the trainsheet), and the vertical profile of the track.  Then it looks at throttle position, whether the throttle is in d/b or power, and brake-pipe pressure.  If the computer calculates the train will stop short given this information, no enforcement will be applied, but it will flash an alert to the engineer that the end of the territory is approaching and an instanteous recommended maximum speed.  If the engineer doesn't brake sufficiently, the system will enforce braking. 

As you would know, railroad rules are "yes/no," that is, you are either on this side of the insulated joint or fouling point and legal, or you are on that side and illegal.  A braking curve is in effect an asymptote and not strictly compatible with a yes/no line unless the braking curve is perfect.  Accordingly, the system has a creep mode that allows a train to creep up to a end of authority.  The railroad can set the parameters however it wants.  For example, it could be set so that the train must be down to 3 mph 150 feet short of the clearance point, then allows a 3 mph creep up to the clearance point.

The system also has a memory feature (if so desired) so that it learns a train's braking characteristics.  For example, if the computer calculates that a deceleration rate ought to be X for a given grade profile, train weight, TPOB, and braking effort (both air and d/b), but it sees that the deceleration rate is actually 1.01X, then it recalculates its braking rate and allowed speed as the train approaches an authority fence or temporary or permanent speed restriction accordingly.  But in no case will it give a train a better rate than its ideal rate, or whatever rate the railroad decides is safe.

As you can see from this, configuration, and configuration management on an on-going basis, has some challenges.  CFR 239 Subpart H establishes the regulation.  Meeting Subpart H is expensive.

RWM

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Posted by erikem on Thursday, October 2, 2008 11:27 PM
 Railway Man wrote:
 oltmannd wrote:
 beaulieu wrote:

Regarding the use of GPS as part of any PTC system, may I suggest reading this article.

 

GPS Spoofing

I would hope that any PTC system would include track transpoders and dead reckoning on top of GPS.

I can't speak for every architecture and manufacturer, but the systems we installed include all three.

RWM

Sounds like at least a few people have a sufficiently high level of paranoia. Too many things can go wrong with GPS even under normal circumstances to use it as the sole means of determining position (e.g tunnels and deep cuts). 

I'm assuming that PTC systems will also rely on track circuits for detecting loose cars or broken rails.

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Posted by Railway Man on Friday, October 3, 2008 12:08 AM

There's at least an order of magnitude more paranoia and distrust in this forum than with anyone I have to deal with in the real world.  I find it interesting how in this forum either GPS is portrayed as either almightier than Oz or more unstable than a Wall Street investment house, but hardly anyone wants to accept that maybe we've put a few tens of millions of dollars of time into thinking through its characteristics.

While some of the PTC systems haven't panned out -- generally because they were designed by non-railroaders who thought they could parachute in and tell us beknighted black-oil types how smart they were -- the systems that have found commercial acceptance have thought through these issues.  It is not necessary to have a continuous signal.  If the locomotive gets a good signal once every 5 minutes that's often plenty.  It maps itself onto the track database stored in its computer when it gets a signal and knows where it is not just from GPS but also dead-reckoning from the axle odometer plus any track tags it passes over.  The locomotive knows where each track tag is supposed to be, and if it passes the location where one is supposed to be and doesn't find it with the tag reader, it stops.  The track tags are paired so one can be knocked off and trains aren't delayed.  The first locomotive that passes over a pair that's missing one reports it.

So you lose the signal in a tunnel, so what?  There's no turnouts in the tunnel.   The locomotive knows the track comes out the other end.

There's more than one way to detect broken rails than a D.C., A.C., or coded track circuit.  You can also use audio overlay frequencies, and get a much greater range than the maybe 10,000 feet you can get with a track circuit under ideal conditions.  Secondly, the value of broken-rail protection through track circuits is greatly overrated.  Most broken rails these days are either "found by a train," that is, they break underneath the train, or are detected as flaws by ultrasonic/electromagnetic testing.  (Metallurgy isn't what it was 50 years ago, which is good and bad.)  If you really want to find broken rails, you run the detector car more often.  That's what the Pilbara lines do, on a weekly basis, for one because they have extremely high axle loads, and for two because track circuits aren't feasible there due to the high conductivity of the roadbed with all the iron fines in the ballast.  Railroads are greatly increasing the sophistication and frequency of rail testing, as Mudchicken will attest.  The quantity of detection gizmos shown off at AREMA this year was mind-boggling when you consider that 25 years ago almost none of these tools existed.

If you want to detect loose cars, you put a U5 (point detector) on the turnouts off the main track, which will tell you when the points are opened for any reason, including a car coming out on its own.  Track circuits will not reliably detect single cars.  Also, put split-point derails on all the industry tracks and wire them with a point detector too.

RWM

 

  • Member since
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  • From: Cardiff, CA
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Posted by erikem on Friday, October 3, 2008 1:45 AM
 Railway Man wrote:

I find it interesting how in this forum either GPS is portrayed as either almightier than Oz or more unstable than a Wall Street investment house, but hardly anyone wants to accept that maybe we've put a few tens of millions of dollars of time into thinking through its characteristics. 

Please bear in mind that I said it is unwise to rely on GPS as the only means of determining position. As you pointed out, most of the time it works quite well. A distinct advantage of GPS over dead reckoning is that the magnitude of position error for GPS is roughly constant over time, but cumulative with dead reckoning. Yet another advantage with GPS is having an accurate time reference in case there is a need to do time comparison of data from different event recorders (but I won't go into the difference between GPS time, UTC, TDT, etc...).

I was using paranoia as a tongue in cheek synonym for caution/prudence. I've experienced one close call at work that resulted from a young, bright, normally cautious, but inexperienced co-worker not thinking through a circuit that he designed and built - a more experienced* worker would have been a bit more "paranoid" about his design.

From what you've wrote about PTC systems, it does sound like many are designed by people with experience and have done a lot of thinking of what could go wrong (heavy use of fail-safe design). I was wondering how the PTC systems would compare with current ABS systems (i.e. what are the tradeoffs?)

Ironically, it is starting to look like the Metrolink accident that started this discusion could have been prevented if the engineer had been paying more attention to the signals than his cell phone. 

 

* Good judgement comes from experience. Experience comes from exercising bad judgement. 

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