[PRCo] Re: MetroRail Signalling

[Herb Brannon]

Two corrections:
1st paragraph, sentence 6: We were on given an overview.................
3re paragraph, sentence 3: .........on the South Patway in the joint
bus/streetcar operations..........
Sorry, I was going too fast.


On Mon, Jun 29, 2009 at 4:46 PM, Herb Brannon <hrbran at cavtel.net> wrote:

> To help fill in a small amount, I can offer the following tiny bit of
> information.  I will, however, go to the GCRTA Rail Training Department and
> check on manuals which explain the cab signal system. RTA uses the same
> system as Washington. Most of the systems are identical, with only local
> variations. We were only give an overview of the operation of the system
> when I was training for rail operator, but I will check for more in depth
> manuals.
>
> The circular wires you mentioned are the "Wee-Z Bonds" mentioned in one of
> the other posts. The box in the center of the rails is, more or less, a
> transmitter/receiver which conveys information to and from a train passing
> over the box. Until I read that post I had thought "Wee-Z Bond" was a name
> applied locally in Cleveland to that device. I guess that's its real name. I
> know RTA has continuous welded rail. There are no gaps in the rail.
>
> I had to forget everything I was taught in training at PATransit. That was
> 'then' and 'now' is light-years ahead of 'then'. Even the newest signal
> system at PATransit when I was there was on the South Patway in the joint
> bus/street operations from Saw Mill Run bridge south to Ansonia Street. That
> system was nothing compared to today.
>
> RTA does not gap the power supply at the Wee-Z Bond locations. Even though
> we use overhead cantenary as opposed to third rail, it is the same
> thing......just elevated above the trains. [This was done at the request of
> the private railroad companies running along side, over and under the rapid
> tracks as a safety measure to protect the railroad workers circa 1954.]
> There are circuit breakers at many locations, but not in direct relationship
> to the Wee-Z Bonds.
>
> Like I said, I will get what I can (and they are always very helpful and
> good about giving out manuals} from the RTA Rail Training Department. I need
> to upgrade my memory banks on this subject also.
>
>
>
>
> On Sun, Jun 28, 2009 at 2:58 PM, Phillip Clark Campbell <pcc_sr at yahoo.com>wrote:
>
>> Mr.Alan Schneider;
>>
>> Thank you very much for this report.  Thank you to the many contributors
>> on
>> this subject.  The news reports  'seem'  well done and I was able to glean
>> much information from them;  comments from contributors underscored these
>> observations and brought much clarity to this disaster.  The postings have
>> been
>> most productive  --  'mostly.'
>>
>> I have changed the subject line and have questions to seek a greater
>> understanding
>> of the signaling system.  I found the URL for the included article:
>> http://www.fredericknewspost.com/sections/news/display.htm?StoryID=91910
>> because I wanted a closer look at the included photo:
>> http://www.fredericknewspost.com/photos/09/06/26/91910_large.jpg
>>
>> It is already established that  'computers'  handle the signals through
>>  'ATC;'  while I
>> understand the concept I am not familiar with the details.  My reference
>> is the US&S
>> signals as used on PRC interurbans.  Rails were gapped and insulated;  an
>> impedance
>> bond allowed ground return around the insulated rails while keeping the
>> signal circuit
>> current within the block.
>>
>> 'Parallel'  construction is evident in the MetroRail photo but the rails
>> are not gapped and
>> insulated are they.  Please note the dual set of cables between the rails
>> in each track
>> that arc through a half circle before attachment to each of the rails;
>>  this  'suggests'  an
>> insulated gap in the rails which, again, is not clearly evident.  There
>> are far more cables
>> between the rails than the parallel US&S impedance bond.
>>
>> Also noteworthy is the large gap in the 600-volt(?) 3rd-rail.  As the
>> cabling between the rails
>> of each track seems identical and the 3rd-rail is gapped on both tracks I
>> am  'assuming'  that
>> such a gap in the 3rd-rail exists wherever such  'signal cables'  exist.
>> Is this true?  Why is
>> it necessary to gap the power supply at signal cabling locations?  Why
>> aren't the running
>> rails gapped, or are they?  I assume each truck has a 3rd-rail shoe on
>> each side;  it then
>> 'seems'  that current is never disconnected from the train as the gap
>>  'seems'  shorter than
>> truck spacing, or is it?  The right hand track has ties that extend
>> further than standard
>> 'apparently'  to accommodate 3rd-rail in the gap area;  the same may be
>> true of the other
>> track but the ties could be covered by the ballast.
>>
>> If someone is able to give some clarity to the computer style ATC signals
>> circuits it will
>> be most appreciated.  Thank you to one and all for such efforts.
>>
>>
>>
>>  Phil
>> Without  a   'coast'   but  not  a   'cause.'
>> --  --
>> "If thou wouldst rule well, thou must rule for God,
>> and to do that, thou must be ruled by Him ...
>> Those who will not be governed by God...
>> ........will be ruled by Tyrants."
>> William  Penn,  founder  of  Pennsylvania
>>
>>
>>
>>
>>
>> ________________________________
>> From: "alschneider2 at juno.com" <alschneider2 at juno.com>
>> To: etennyson at cox.net
>> Cc: rejmhj at netzero.net; j_swindler at hotmail.com; pcc_sr at yahoo.com;
>> pittsburgh-railways at dementia.org; jack.may at americomm.net;
>> gary-elaine at comcast.net; nawdry at bga.com; crvlkotula at aol.com;
>> philgcraig204 at yahoo.com; billvigrass at verizon.net;
>> bob.dietrich1 at verizon.net; bbente at bellsouth.net; trams2 at comcast.net;
>> allmanr at verizon.net; shadow at dementia.org; akftrain at aol.com;
>> miklosfrank at comcast.net; jaurelius at centurytel.net;
>> russell.jackson at stvinc.com
>> Sent: Sunday, June 28, 2009 10:27:36 AM
>> Subject: Re: METRORAIL DISASTER-DEFFERED MAINENANCE?
>>
>>
>> FrederickNewsPost.com
>>
>> Source: Metro circuits were malfunctioning for five days
>> Originally published June 26, 2009
>>
>>
>> By Marge Neal
>>
>>
>>
>>
>>  Photo by Associated Press
>>
>>
>> Workers install new fencing Wednesday in Washington, at the site where two
>> Metro trains crashed Monday.
>>
>>
>>
>>  Two track circuits in the area of Monday's deadly Metro crash alternately
>> reported the track as vacant and then occupied almost constantly from June
>> 17, when a part of a signaling device was replaced, until the time of the
>> crash, according to a Metro source.
>> The circuits appeared to have intermittently lost track of the trains
>> involved in the crash of two Metro trains that killed nine people, according
>> to Metro documents obtained by The Frederick News-Post.
>> The documents show what is known as "flip-flopping," with the circuit
>> alternately reporting the track as "occupied" and then "vacant." The report
>> for track circuit number B2-304, where the stopped train was located, starts
>> at 4:45 p.m. and ends at 5:38 p.m., about 40 minutes after the crash.
>> Throughout the time period covered by the report, the circuit shows the
>> track either occupied or vacant as often as every couple of seconds.
>> At 4:57:03 p.m., about the time of the crash, the report shows the track
>> to be vacant until 5:37:44, when it reports the track is occupied. Less than
>> a minute later, the report again states the track was vacant, even though
>> train wreckage was on the track. One second after that, the track was
>> reportedly occupied again. The circuit flip-flopped again before finally
>> showing the track to be occupied at 5:38:40.
>> On June 17, a part of the track signaling device known as a Wee-Z Bond was
>> replaced in the area of the crash, according to a Metro source who spoke on
>> the condition of anonymity. The Frederick News-Post agreed to the request
>> because of the compelling nature of the information.
>> The two track circuits involved in the crash -- B2-304 and B2-312 -- share
>> the bond that was replaced. The component feeds the receiver for one and
>> gets the signal from the transmitter for the other.
>> Both circuits continued to alternately report the track as vacant and then
>> occupied almost constantly from June 17, when the part was replaced, to the
>> time of the crash, according to the Metro source.
>> "Without seeing the schematic drawings of the (Wee-Z Bond), I cannot say
>> it failed or contributed to this crash," Najm Meshkati, professor of civil
>> and environmental engineering at the University of Southern California, said
>> Thursday. "I can say the system did not get back to its normal operating
>> mode after the replacement was made."
>> The replacement part did not perform its intended purpose, Meshkati said.
>> The part could have been defective, or it could have needed to be
>> recalibrated or reset to work properly, he said.
>> Metro, he said, needs to take a "hard look" at its systems safety
>> practices and philosophy.
>> "It is important not to blame," he said. "It's important to find the root
>> cause of the problem and change the safety culture of the organization."
>> The Frederick News-Post has also learned that Matthew L. Matyuf,
>> superintendent of the Automatic Train Control division, was relieved of his
>> duties after the crash.
>> "I can confirm that the ATC superintendent has been temporarily assigned
>> to a special project," Lisa Farbstein, Metro's chief spokeswoman, said
>> Thursday. "It happened post-incident, and I do not know what the project
>> is."
>> Wednesday night, investigators from the National Transportation Safety
>> Board conducted tests using a similar train at the crash site, according to
>> a press release from the agency. When the train was stopped at the same
>> location as the stopped train that was hit, the train control system lost
>> detection of the test train.
>> Investigators are continuing to examine trackside circuits and train
>> control system data to understand how the train control system functioned on
>> the day of the crash, according to the release.
>> Recorder data have been recovered by the struck train. The striking train
>> did not have any onboard accident data recorders, according to NTSB.
>> The operator of the striking train, Jeanice McMillan, was killed in the
>> impact. NTSB investigators found metal-to-metal compression streak marks on
>> both rails of the track for about 125 feet ending near the point of impact,
>> consistent with heavy braking, the release states.
>> McMillan apparently pressed a "mushroom" button to activate an emergency
>> brake.
>> The operator of the struck train was interviewed Thursday morning,
>> according to the release. He told investigators that he operated his train
>> in manual mode during his entire shift that afternoon. He said he had
>> stopped to wait for a train that was stopped in front of him when his train
>> was struck.
>> NTSB said investigators will continue to document evidence at the accident
>> scene and intend to conduct sight distance tests using trains similar to
>> those involved in the crash.
>>
>>
>>
>>
>>
>>
>
>
> --
> Herb Brannon
> On America's North Coast  <TM>
> That's another fine mess you've gotten me into.
> *Oliver Hardy** *
>
>


-- 
Herb Brannon
On America's North Coast