nels@astrovax.UUCP (Nels Anderson) (12/21/85)
Could someone explain the signals used on New York's subway system? There is
quite a variety of them, with different numbers of red, yellow and green lamps
in various arrangements.
-- Nels Anderson
--
Nels Anderson Princeton University, Astrophysics
{allegra,akgua,burl,cbosgd,decvax,ihnp4,noao,princeton,vax135}!astrovax!nelspercus@acf4.UUCP (Allon G. Percus) (12/22/85)
Basically, when there is a standard signal with three lights, they mean
the usual things: green -- proceed, amber -- proceed with caution
expecting more amber and red signals to come, red -- come to a full stop --
if you don't, an automatic "tripper" from underneath the signal will
force the emergency brakes on the train.
A stack of one three-light signal on top of another means as follows:
green over green -- proceed on main track, green over yellow -- proceed
on diverging track, yellow over green -- proceed with caution on
main track, yellow over yellow -- proceed with caution on diverging
track, and red over anything OR anything over red -- come to a full stop.
.
-------
|-----| A. G. Percus
|II II| (ARPA) percus@acf4
|II II| (NYU) percus.acf4
|II II| (UUCP) ...{allegra!ihnp4!seismo}!cmcl2!acf4!percus
|II II|
-------BSG@SCRC-STONY-BROOK.ARPA (Bernard S. Greenberg) (12/23/85)
(I could not send To: nels@astrovax.uucp.arpa, somebody please forward if he's
not on Railroad@rochester, which is certainly not likely)
Date: 21 Dec 85 16:02:13 GMT
From: Nels Anderson <nels@astrovax.uucp.arpa>
Could someone explain the signals used on New York's subway system? There is
quite a variety of them, with different numbers of red, yellow and green lamps
in various arrangements.
-- Nels Anderson
--
Nels Anderson Princeton University, Astrophysics
{allegra,akgua,burl,cbosgd,decvax,ihnp4,noao,princeton,vax135}!astrovax!nels
Date: 22 Dec 85 15:37:00 GMT
From: "Allon G. Percus" <percus@acf4.uucp.arpa>
Basically, when there is a standard signal with three lights, they mean
the usual things: green -- proceed, amber -- proceed with caution
expecting more amber and red signals to come, red -- come to a full stop --
if you don't, an automatic "tripper" from underneath the signal will
force the emergency brakes on the train.
A stack of one three-light signal on top of another means as follows:
green over green -- proceed on main track, green over yellow -- proceed
on diverging track, yellow over green -- proceed with caution on
main track, yellow over yellow -- proceed with caution on diverging
track, and red over anything OR anything over red -- come to a full stop.
This is only part of the story.
This is one of my favorite subjects in the world.
The system Percus has just described is the newer system, which started on
the BMT and IND, and is slowly being installed on the IRT. The upper head
of a multi-head ("home") signal is indeed equivalent to a block signal, and
the lower head is "green is straight, yellow is diverging", and reds
only occur together. The following addenda to this are necessary:
It is physically possible to pass a single red light by creeping up
into the next section so slowly that it is noticed by the track circuit
before you are tripped. This will lower the tripper. This action
has been forbidden by regulation for about 10 years, but has not been
modified out of the system. This is not possible for a double red
light ("Stop and Stay").
Under a double red light, a single yellow can appear ("Call-on"), requiring
an interaction to lower the tripper. The towerperson (all double signals
involve an element of manual control) can elect this option only if the
-only- reason the signal is red is the presence of trains in the blocks
ahead of it (i.e., there are not switches set against it, signals set
against it, etc.)
There are several schemes of time-dependent indications (grade time,
"station time"), I will not bore the list with the details unless someone
prods me further...
The older system of home signal indication, installed with the original IRT
in 1904, is somewhat different, and corresponds to what is in use in
much standard railroading. It also has the neat feature that it is extensible,
which the newer system is not.
A multi-headed signal in this scheme has one head corresponding to each
possible route. Normally, the upper head is the "straight" route, and the
lower the diverging. It is possible to have multiple diverging routes, and
hence three heads. "Proceed with caution on diverging route" would be
Red over Yellow (perhaps over another red if there are more than two).
"Proceed on main route" would be Green over Red. Note that other than
red over red, there are no shared aspects (the actual pattern of lights,
as opposed to their "indication", or semantics) with the newer system.
IRT home signals controlling paths over which there is no choice have
single heads. You can tell them (as all old IRT home signals) by their
red number-plates. You cannot force the tripper down by approach
(automatic key-by), so their "stop" indication indeed has the force of
home signals.
I can go on at any length or depth on this that anyone wants to hear. I
spent a large part of my childhood and adolescence in NY roaming the
subways, communicating with the then-NYCTA, collecting prints, circuit
diagrams, interlocking plans, etc....Burton.osbunorth@Xerox.ARPA (12/23/85)
I agree that signalling on the NYC subway system is a fascinating topic. About 12 years ago, for a master's thesis at the then Brooklyn Polytechnic Institute, I designed a computer simulation of the subways. I got deep into the dynamics of the signalling, and also collected old drawings, etc. On a related topic. I have a 1944 Book of Rules. Is there a more recent edition? Anyone want to trade copies? Phil Burton Xerox Corporation
larry@kitty.UUCP (Larry Lippman) (12/25/85)
>> Could someone explain the signals used on New York's subway system? There is >> quite a variety of them, with different numbers of red, yellow and green >> lamps in various arrangements. > ... > This is only part of the story. > This is one of my favorite subjects in the world. Mine, too! One of my favorite books (I am into historical technology) is a reprint of a book entitled: "Interborough Rapid Transit" originally published in 1904, and reprinted by The Arno Press, LC number 71-90436. This book provides a number of fascinating photographs and details on the first New York City subway system; there is about 10 pages on the signalling system. > I can go on at any length or depth on this that anyone wants to hear. I > spent a large part of my childhood and adolescence in NY roaming the > subways, communicating with the then-NYCTA, collecting prints, circuit > diagrams, interlocking plans, etc.... I'd love to find out more details, and would like to get some further documentation for my "collection" if you have any sources. ==> Larry Lippman @ Recognition Research Corp., Clarence, New York <== ==> UUCP {decvax|dual|rocksanne|rocksvax|watmath}!sunybcs!kitty!larry <== ==> VOICE 716/741-9185 {rice|shell}!baylor!/ <== ==> FAX 716/741-9635 {G1, G2, G3 modes} duke!ethos!/ <== ==> burl!gladys!/ <== ==> "Have you hugged your cat today?" ihnp4!/ <==
edg@micropro.UUCP (Ed Greenberg) (12/27/85)
Please be informed that I have several New York City Transit Authority
rulebooks (for subway) and will be happy to answer questions based on
looking things up in them.
Please note that I do not claim any other expertise in the subway system
(or trains in general) than some years of riding the subway (usually at
the front window) and those books.
-e
--
Ed Greenberg; MicroPro International Corp. (disclaimer)
UUCP: {hplabs,ptsfa,glacier,lll-crg}!well!micropro!edg
{ucbvax,decwrl}!dual!micropro!edg
AT&T: 415-499-4096Burton.osbunorth@Xerox.ARPA (12/27/85)
Ed, Sounds good. What years are the books? Phil Burton Xerox Corp. 415 496 6514
4373jml@homxb.UUCP (J.LISS) (12/31/85)
It seems that NYC subway signaling is hot topic. If memory serves correct, there was only 1 subway station in NYC that the passangers had to actually cross the tracks to reach the station. Where is the station ? And was there special signalling there ?
rees@apollo.uucp (Jim Rees) (01/02/86)
It seems that NYC subway signaling is hot topic. If memory serves
correct, there was only 1 subway station in NYC that the passangers had
to actually cross the tracks to reach the station. Where is the station ?
And was there special signalling there ?
I don't know, but the oldest subway station in the US, Park Street Station
on Boston's green line, still has surface level tracks on the upper level
that you have to cross if you want to get a doughnut (unless you want to
go downstairs and cross via the red line platform). I keep expecting a
bad accident and subsequent lawsuit here, but it hasn't happened yet.