Trains.com

PTC ? A threat to GPS is being recognized by ocean shipping

6340 views
50 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    January 2001
  • From: MP CF161.6 NS's New Castle District in NE Indiana
  • 2,148 posts
Posted by rrnut282 on Friday, August 25, 2017 11:07 AM

IslandMan

....

If the sort of funds used for R & D in IT were diverted to materials science it might be possible to make machines with the same sort of lifespan as static structures, e.g. automobiles lasting centuries.  In this scenario total raw material consumption would drop to low levels as would the amount of labor needed to make stuff.  

 

This has been the case since shortly after the industrial revolution.  The biggest reason this hasn't come to pass, is what do you do with the factory and supply-chain employees between the 100year demands?  That's a lot of welfare checks to write.  Also, they aren't buying the other guys' widgets (and keeping those employees working) without a paycheck. 

Mike (2-8-2)
  • Member since
    March 2016
  • 123 posts
Posted by IslandMan on Friday, August 25, 2017 6:17 PM

rrnut282

 

 
IslandMan

....

If the sort of funds used for R & D in IT were diverted to materials science it might be possible to make machines with the same sort of lifespan as static structures, e.g. automobiles lasting centuries.  In this scenario total raw material consumption would drop to low levels as would the amount of labor needed to make stuff.  

 

 

 

This has been the case since shortly after the industrial revolution.  The biggest reason this hasn't come to pass, is what do you do with the factory and supply-chain employees between the 100year demands?  That's a lot of welfare checks to write.  Also, they aren't buying the other guys' widgets (and keeping those employees working) without a paycheck. 

 

 

 

It's a thought rather than a practical proposition, a bit like those 'what if?' scenarios that historians sometimes like to pose (e.g. Abraham Lincoln being assassinated prior to the Civil War, or the German conquest of Britain in 1940).  The idea came to me after watching a TV history program. In the days before coal was used as a fuel for cooking, cooking pots were handed down as family heirlooms and would sometimes last 400 years (pots for cooking on wood fires in Europe were roughly spherical in shape with three legs, exactly like the vessels used by witches in kids' books to brew up 'eye of newt and tongue of toad').

If any 'longevity revolution' came about there would be a gradual increase in the lifespans of consumer durables ("consumer very durables"? "consumer extremely durables"?). Primary manufacturing would eventually drop to a low level, mainly catering for population increases and replacing accident damage.  The emphasis would shift towards repair, rebuilding and remanufacturing.  The workshop would tend to replace the factory. In a sense it would be the Industrial Revolution as Henry Thoreau might have conceived it.

Back in the real world, automation will reduce demand for labor drastically in the very near future (some economists talk of a halving of the number of workers within 20 years, and of course there is no reason to suppose that the process would suddenly stop then) and hence cause a collapse in spending power.  This is a fundamental problem that no-one seems to have addressed beyond some half-baked proposals for a guaranteed universal income.

RME
  • Member since
    March 2016
  • 2,073 posts
Posted by RME on Friday, August 25, 2017 6:52 PM

IslandMan
rrnut282
IslandMan

If the sort of funds used for R & D in IT were diverted to materials science it might be possible to make machines with the same sort of lifespan as static structures, e.g. automobiles lasting centuries.  In this scenario total raw material consumption would drop to low levels as would the amount of labor needed to make stuff.

This has been the case since shortly after the industrial revolution.  The biggest reason this hasn't come to pass, is what do you do with the factory and supply-chain employees between the 100year demands?  That's a lot of welfare checks to write.  Also, they aren't buying the other guys' widgets (and keeping those employees working) without a paycheck.

It's a thought rather than a practical proposition, a bit like those 'what if?' scenarios that historians sometimes like to pose (e.g. Abraham Lincoln being assassinated prior to the Civil War, or the German conquest of Britain in 1940).

The most likely way that such a sea-change in manufacturing would come about would be a gradual increase in the lifespans of consumer durables ("consumer very durables"? "consumer extremely durables"?). Primary manufacturing would eventually drop to a low level, mainly catering for population increases and replacing accident damage.  The emphasis would shift towards repair, rebuilding and remanufacturing.  The workshop would tend to replace the factory.

Back in the real world, automation will reduce demand for labor drastically in the very near future (some economists talk of a halving of the number of workers within 20 years) and hence cause a collapse in spending power.

Actually, I observed this being discussed in the first week of 'engineering school', right after learning the 'purpose of engineering' (which made me so irate then, and still does now) -- and it is tied up with that in several ways.

Materials science capable of vastly extending product lifespan can, and is, often better used to decrease product weight, first cost, required complexity, or to make things capable of performance unrealizable with "longer-lived" construction -- the old Space Shuttle being a canonical example in a number of respects, but much of aviation in general almost 'since the beginning' contributing significant examples.

Likewise, a great part of design (especially in Europe) has involved the specification of recyclable materials and components, not just in the obvious (aluminum or thermoplastics) but in designs that permit new 'skinning' of older functional equipment.  With respect to a great deal of 'information technology' where circuitry has no inherent 'age limit' it definitely becomes possible to start thinking of very extended service life (and the peripheral designs that make it more practical) - this is not in the 'one-horse shay' kind of interdependent structural life I think you meant, but involves non-wearing and non-degrading components or equipment.

However, there are other things that affect this.  Planned product obsolescence (to use Vance Packard's term) comes in two general flavors, only one of which is to build things as cheap as possible so they fail and have to be replaced.  The other version, formerly exemplified by Japanese electronics manufacturers and now by crApple et al., is to establish markets where consumers, not technical dysfunction or increasing maintenance costs, make the decision to trash or shuck older devices that are still functioning perfectly well.  (crApple for a while had helpful employees who would flat lie about problems with their toys, and the need to buy new ones because the old ones 'just stopped working' after a certain number of years, but that of course is another story)

We already see where the repair, rebuilding, and remanufacturing business will go -- convenient trade-in machines in supermarkets that offer you $3 for a phone that cost you $300 or more, and which presumably the remarketers will demand significant money in the aftermarket ... or make a profit by parting out to companies that provide while-u-wait repairs at costly prices. 

Automation had its effect on the demand for labor by the '80s, as did outsourcing; the argument for classical Marxist 'blue-collar' labor has nowhere near as much relevance to economics as does the current decline of the 'middle class' no matter what the SEIU people or other flacks may try to establish.  That does not change the fact -- which I think is correct in the right context -- that a collapse in effective spending power may well come in the next 20 years.  I don't think this is directly related either to the level of automation that produces better products, or to any degree of further automation that produces less effect from reducing consumer prices than it does in reducing taxable income for those consumers paying the prices.

  • Member since
    May 2003
  • From: US
  • 25,292 posts
Posted by BaltACD on Friday, August 25, 2017 7:59 PM

I have 2 residences - one in Jacksonville and one in Maryland.  The refrigerator (and for that matter all the appliances) came with the house when I bought it in 1990 and they are all still going strong - I believe they all date from the late 60's or early 70's from the Harvest Gold and similar colors that they are.

I first rented my Jacksonville place in 1991 and ended up buying it in 1998 after the landlord tried (unsuccessfully) to sell it 3 times before I bought it.  Since 1991 it has had 4 refrigerators, 2 dishwasher and a heat pump.

Yep!  They don't build things to last these days.  I guess my Dodge Durango is an anomoly with over 351K on the clock.

Never too old to have a happy childhood!

              

  • Member since
    April 2002
  • From: Northern Florida
  • 1,429 posts
Posted by SALfan on Friday, August 25, 2017 11:53 PM

BaltACD

I have 2 residences - one in Jacksonville and one in Maryland.  The refrigerator (and for that matter all the appliances) came with the house when I bought it in 1990 and they are all still going strong - I believe they all date from the late 60's or early 70's from the Harvest Gold and similar colors that they are.

I first rented my Jacksonville place in 1991 and ended up buying it in 1988 after the landlord tried (unsuccessfully) to sell it 3 times before I bought it.  Since 1991 it has had 4 refrigerators, 2 dishwasher and a heat pump.

Yep!  They don't build things to last these days.  I guess my Dodge Durango is an anomoly with over 351K on the clock.

 

My grandparents bought a GE refrigerator in 1939, and an International Harvester freezer (yes, you read that right, IH freezer) in 1946.  Both were still going strong when my grandmother died in 1973.  My cousin, who bought the house from my grandmother's estate, used both for some period after that.  Both of those appliances were built like tanks (I ought to know, I helped move them around a time or two).

  • Member since
    July 2014
  • 565 posts
Posted by Fred M Cain on Tuesday, September 19, 2017 1:02 PM

The Wall Street Journal had an artical in it about a week or so ago concerning the staggering number of satellites that are now in orbit.  They are guessing that there are at least 20,000 of them but that's just a guess 'cause no one knows for sure and dozens more are getting launched every week. Some of them are no larger that the size of softball.

The concern is, what if one or more of them hit and knock out GPS satellites?  The article didn't mention railroads but I got to wondering, what if that were to happen and knock out PTC? Will the trains just have to stop?  Or, would they be permitted to revert to old operating rules?  Would they have to operate at restricted speed?

This poses some disturbing questions.  PTC might turn out to be  a nightmare.  One can recall years ago when the BART first opened with few or no wayside signals and all operated by computer.  It was an ungodly nightmare until they finally got all the bugs out of it.  BART was up and running, or tried to, before the technology was fully developed and perfected.  Will history repeat itself with PTC?

Regards,

Fred M. Cain

  • Member since
    December 2005
  • From: Cardiff, CA
  • 2,930 posts
Posted by erikem on Tuesday, September 19, 2017 1:46 PM

The number of satellites in GPS orbit are much lower than low earth orbit (LEO). OTOH, the orbit is pretty tightly defined, so there is a chance of a repeat of the COSMOS/Iridium collision of a few years back.

GPS was designed with a lot of redundancy, so the loss of one satellite will not have much of an effect unless the receiver is in an location with limited view of the sky. Examples would be canyons whether their natural or urban in origin.

One mitigation against GPS spoofing would be using a phased array antenna for reception as the positions of the satellites are well known, signals not coming from the expected location would be ignored. This would also help with multipath.

  • Member since
    May 2003
  • From: US
  • 25,292 posts
Posted by BaltACD on Tuesday, September 19, 2017 2:09 PM

erikem
The number of satellites in GPS orbit are much lower than low earth orbit (LEO). OTOH, the orbit is pretty tightly defined, so there is a chance of a repeat of the COSMOS/Iridium collision of a few years back.

GPS was designed with a lot of redundancy, so the loss of one satellite will not have much of an effect unless the receiver is in an location with limited view of the sky. Examples would be canyons whether their natural or urban in origin.

One mitigation against GPS spoofing would be using a phased array antenna for reception as the positions of the satellites are well known, signals not coming from the expected location would be ignored. This would also help with multipath.

Some of my GPS devices identify the number of GPS satellites the device is in contact with - the number varies - generally between 8 & 11.  I really don't know how many GPS satellites there are aloft.

Never too old to have a happy childhood!

              

  • Member since
    July 2014
  • 565 posts
Posted by Fred M Cain on Tuesday, September 19, 2017 2:36 PM

Those are both good points (erikem & BalACD) but the question still remains, what would happen to a running railroad in the event of a PTC crash? Or is that something that we can be completely confident will never happen?

Regards,

Fred M. Cain

  • Member since
    May 2003
  • From: US
  • 25,292 posts
Posted by BaltACD on Tuesday, September 19, 2017 4:40 PM

Fred M Cain
Those are both good points (erikem & BalACD) but the question still remains, what would happen to a running railroad in the event of a PTC crash? Or is that something that we can be completely confident will never happen?

Regards,

Fred M. Cain

PTC as it is being implemented on the Class 1 carriers is an overlay on the already existing systems.  Those systems are Automatic Block Signal Systems and Track Warrant Control of specific tracks.

PTC in being a overlay, ENFORCES, the signal aspects that it gets fed from the track various radio devices associated with the switches and signals on the territory.  In TWC territory the dispatcher defined limits of the authority, while enforced by GPS locations, are still 'paper limits' that the crew must obey.

Each carrier, in their implementation of PTC has also implemented rules and procedures for operation in the absence of PTC for any of a wide variety of reasons.

In the absence of operative PTC, the Class 1's will continue to operate until PTC is restored.  Remember PTC is only being installed on a portion of the Class 1 carriers trackage.  Thousands of miles of the Class 1's systems will be operating without PTC and without PTC being required.

What the governmentally funded commuter rail systems are implementing, I have no idea - other than is must be compatible with the Class 1 systems where these carrier operate on Class 1 trackage.

Never too old to have a happy childhood!

              

  • Member since
    February 2008
  • From: Potomac Yard
  • 2,767 posts
Posted by NittanyLion on Tuesday, September 19, 2017 5:06 PM

erikem

The number of satellites in GPS orbit are much lower than low earth orbit (LEO). OTOH, the orbit is pretty tightly defined, so there is a chance of a repeat of the COSMOS/Iridium collision of a few years back.

GPS was designed with a lot of redundancy, so the loss of one satellite will not have much of an effect unless the receiver is in an location with limited view of the sky. Examples would be canyons whether their natural or urban in origin.

One mitigation against GPS spoofing would be using a phased array antenna for reception as the positions of the satellites are well known, signals not coming from the expected location would be ignored. This would also help with multipath.

 

erikem

The number of satellites in GPS orbit are much lower than low earth orbit (LEO). OTOH, the orbit is pretty tightly defined, so there is a chance of a repeat of the COSMOS/Iridium collision of a few years back.

GPS was designed with a lot of redundancy, so the loss of one satellite will not have much of an effect unless the receiver is in an location with limited view of the sky. Examples would be canyons whether their natural or urban in origin.

One mitigation against GPS spoofing would be using a phased array antenna for reception as the positions of the satellites are well known, signals not coming from the expected location would be ignored. This would also help with multipath.

 

There's also the matter of MEO being ten times the size of LEO, so there's just plain more volume to cram all those satellites in.

  • Member since
    March 2003
  • From: Central Iowa
  • 6,900 posts
Posted by jeffhergert on Tuesday, September 19, 2017 6:28 PM

PTC is operative in an interim phase in my area.  On the portions equipped with either cab signals or automatic train control, if the locomotive is equipped with PTC we run with that engaged.  The CCS or ATC is cut out.  If the engine isn't equipped with PTC or it fails, the CCS/ATC needs to be cut in.

When setting up the PTC in locations of multiple possible tracks, it asks which track you are currently on.  If not on a PTC track, such as in a yard, it will give an "unmapped track" option.  This allows actual selection to be made after a PTC track is occupied.  Once when entering from an unmapped section onto main track one, I selected track one and confirmed it.  Still the PTC system put us on track two, and started counting down to a penalty brake application because the next signal was at stop.  I was able to make a normal, non-penalty stop and then reselect location.  This time it took and we continued on.  From this experience, I don't think PTC currently relies completely on GPS for train location.  I think it may use track circuits and/or logic to help place a train on the map on the correct track.  I've noticed when comparing the mapped location to actual location it can still be off by 100-150 feet at times.

So far, most (including me) seem to like PTC.  You can "see" about 5 miles ahead and can tell if you're lined up straight or to crossover at control points.  One thing I don't like is at one crew change point, the pad is about 150 feet from an absolute.  If the dispatcher can't give you a signal you have to crawl up to it to avoid the penalty brake application.  Was fun with a 20000 ton sand train last week moving at 1 mph.

Jeff

  • Member since
    December 2007
  • From: Georgia USA SW of Atlanta
  • 11,919 posts
Posted by blue streak 1 on Tuesday, September 19, 2017 7:16 PM

GPS has at least 35 operating satelites at last count.  As well there are several older less sophiscated that are in standby orbit.  Note there are 3 distinct orbit altitudes as well as some polar orbits.

As far a penalty braking is concerened at least 1 out of 10 south bound CSX  trains here take a penalty slow when traversing our local siding.  They either have to stop or slow to less than  5 (?)  MPH. That is even with clear signals at both ends of sidings.

  • Member since
    May 2003
  • From: US
  • 25,292 posts
Posted by BaltACD on Tuesday, September 19, 2017 7:41 PM

blue streak 1
GPS has at least 35 operating satelites at last count.  As well there are several older less sophiscated that are in standby orbit.  Note there are 3 distinct orbit altitudes as well as some polar orbits.

As far a penalty braking is concerened at least 1 out of 10 south bound CSX  trains here take a penalty slow when traversing our local siding.  They either have to stop or slow to less than  5 (?)  MPH. That is even with clear signals at both ends of sidings.

GPS implemented at present is in a 'production testing' enviornment.  Put it in place, see what problems crop up and fix the problems.  Can't speak for the other carriers, CSX had (before EHH) a entire department following up on the reported PTC issues and working to correct them going forward.  In December 2016 when I retired PTC had been implemented on 29 Subdivisions of all kinds of operating characteristics.  I don't know how many more subdivisions have been implemented since I retired - but I do know that more have been implemented.

Never too old to have a happy childhood!

              

  • Member since
    December 2005
  • From: Cardiff, CA
  • 2,930 posts
Posted by erikem on Tuesday, September 19, 2017 9:31 PM

blue streak 1

GPS has at least 35 operating satelites at last count.  As well there are several older less sophiscated that are in standby orbit.  Note there are 3 distinct orbit altitudes as well as some polar orbits.

My recollection (perhaps mistaken) was that the GPS satellites orbited in three distinct orbital planes and all orbits were of the same radius. The intent was that every spot on earth would have at least four satellites in view at all times, preferably more. To get a good fix, three of the satellites need to reasonably orthogonal to each other. Some of the requirements can be relaxed if the receiver has a good timebase (i.e. atomic clock), which would allow a 3D fix with only three reasonable placed satellites. Keep in mind that a 10E-10 error (gain/loss of 1 second every 300 years) will cause a position drift of up to 1 foot every 10 seconds.

  • Member since
    December 2007
  • From: Georgia USA SW of Atlanta
  • 11,919 posts
Posted by blue streak 1 on Wednesday, September 20, 2017 11:59 AM

Erikem is correct.  One item that keeps GPS accurate is at 0700 mountain time Fallon Air Force base initiates an update to the atomic clocks in the sattelites.  Since they are in different orbital planes relativity comes into play due to their different oribital speeds the clocks need resetting.  Wonder how that is mitigated when universal time has the occasional second added ?

GPS positioning for aircraft has the additional problem in that aircraft fly pressure altitude not absolute altitude.  The GPS receivers there for have to take  a reading from aircraft air data computer to make required adjustments.  pressure altitude is affected by outside air temperature so when air is hotter than standard the aircraft will be higher than absolute altitude.

  • Member since
    December 2001
  • From: Northern New York
  • 25,019 posts
Posted by tree68 on Wednesday, September 20, 2017 12:10 PM

erikem
My recollection (perhaps mistaken) was that the GPS satellites orbited in three distinct orbital planes and all orbits were of the same radius. The intent was that every spot on earth would have at least four satellites in view at all times, preferably more.

http://www.gps.gov/systems/gps/space/
The satellites in the GPS constellation are arranged into six equally-spaced orbital planes surrounding the Earth. Each plane contains four "slots" occupied by baseline satellites. This 24-slot arrangement ensures users can view at least four satellites from virtually any point on the planet.

They fly at 12,550 miles, and there are currently seven operational spares flying as well.

I use an app on my phone called "GPS Test" quite often, and can usually see at least 7 birds.

LarryWhistling
Resident Microferroequinologist (at least at my house) 
Everyone goes home; Safety begins with you
My Opinion. Standard Disclaimers Apply. No Expiration Date
Come ride the rails with me!
There's one thing about humility - the moment you think you've got it, you've lost it...

  • Member since
    December 2001
  • From: Denver / La Junta
  • 10,820 posts
Posted by mudchicken on Thursday, September 21, 2017 9:19 PM

If you have anything less than 5 "birds", the precision (and by default, the accuracy) goes down the rabbit hole. If your constellation  of 5 or fewer birds is out on the horizon, your actual position really blows up when trying to check your relationship to something else nearby. It wasn't that long ago, after the Challenger tragedy, GPS got to be very dicey to work with - it still isn't 100% useful. For whatever reason, if you don't have the spares and your older birds start to fail, you find yourself to be working at 2AM and checking an ephemeris constantly to make sure you have good data - a serious threat to PTC's reliability. The old dinosaur systems become the backbone of what keeps the system fluid which can't run only at certain hours.

Mudchicken Nothing is worth taking the risk of losing a life over. Come home tonight in the same condition that you left home this morning in. Safety begins with ME.... cinscocom-west
  • Member since
    December 2007
  • From: Georgia USA SW of Atlanta
  • 11,919 posts
Posted by blue streak 1 on Thursday, September 21, 2017 9:39 PM

MC:  Thanks for reminding about the less than 5 birds in view good view.  Aircraft GPS navigation is not solely permitted when that restriction is in effect.  Often that restriction will only be for a couple hours or less.  That is why now most modern aircraft ( B-757 and later + older aircraft refits) have inertial reference units installed  ( IRS, IRU ) These units are relatively inexpensive compared to older inertial units costing 1975 as $250,000 per unit.  ( 3 in early B-747s ).

Now days these newer units are required for many over ocean and non radar routes because of the potential of not enough birds in view 2 hours before and after a flight. .

Now what MC stated about using GPS at 0200 is what this poster worries about putting too many eggs in the GPS basket.

  • Member since
    September 2008
  • 1,112 posts
Posted by aegrotatio on Thursday, September 21, 2017 10:25 PM

I worked for a satellite terminal provider that tried to get one of the Class 1's interested in using their VSAT terminals.  The subject of rain fade came up.  These days both the uplink facility and the VSAT terminals power up and down to compensate for rain fade but there will be times when the service is disconnected.

 

When that happens, all signals in the block(s) served by that terminal are to drop to danger immediately.

 

The Air Force publishes scheduled GPS outages.  A friend of mine who was a hobbyist pilot once showed me a web site that mapped and animated the scheduled outages for pilots to know when GPS is degraded.  It's a real thing.

 

But what people don't seem to remember is that trains frequently travel in tunnels that have no GPS coverage at all.

 

  • Member since
    December 2007
  • From: Georgia USA SW of Atlanta
  • 11,919 posts
Posted by blue streak 1 on Friday, September 22, 2017 4:56 PM

There is a new threat to GPS.  "IF" a certain country does an atmosphere or above atmosphe test of a neculear explaosion depending on the explosion nature  ( possible EMP ) it could have anywhere from minimal to serious damage to the satellites in view.  At least Fallon might initiate a temporary shutdown of any satellites that would be in view ? 

Other GPS type satellites might also be vulnerable as wel as many other types of satellites.

Join our Community!

Our community is FREE to join. To participate you must either login or register for an account.

Search the Community

Newsletter Sign-Up

By signing up you may also receive occasional reader surveys and special offers from Trains magazine.Please view our privacy policy