Re: (erielack) Staggered Heads

[Gordon Davids <g.davids_@_verizon.net>]

COMMENT: Interesting again! I never thought about that -- what is the 
advance signal against a diverging route thru an interlocking with the 
next signal in stop (i.e., "medium approach", red over yellow over red, 
Erie style, or red over flashing yellow, DLW style, or one-arm flashing 
yellow (i.e., Rule 286C, not sure where that was used)? Obviously it was 
approach medium at Cuba Jct., perhaps in most other places on the EL.

 >> If the diverging route indication was "Clear Medium" or "Medium 
Approach," the signal to the rear (governing the approach to the 
interlocking" would be "Approach Medium."  If the diverging route was 
"Clear Slow," the signal to the rear would indicate "Approach Slow."

MY QUESTION -- Does anyone know the rationale for EL Rule 284 (the 
"Berkshire rule"? just kidding), called approach-slow, a 3 arm automatic 
with aspect yellow over red over green, meaning "approach next signal at 
not exceeding slow speed", slow speed being 15 MPH. In a way, it's not 
as restrictive as "approach", you don't have to prepare to stop at the 
next signal. But, you need to crawl.

My GUESS would be that this could be used as an advance indication to an 
interlocking signal where a diverging move onto unsignalled territory is 
expected, such as a switch into a yard. I.e., you'd see a 
yellow-over-red-over-green at the automatic in advance of an 
interlocking where your interlocking signal is already pulled off and is 
displaying "restricting", i.e. red over yellow. (Again, that's just my 
THEORY, wondering what the real deal is -- or was, back when the EL was 
still around.)

So you'd come up on the interlocking at 15 mph, and hopefully be in good 
shape to get down to restricted speed (i.e., prepare to stop short of 
obstruction on visual warning). I never saw a 3-arm automatic on the 
Erie / EL, although I was told that they existed. (The CNJ main east of 
Raritan had some of them, I did see those.) On most of the interlockings 
on the NY Div that I was familiar with, the advance to a "restricting" 
would be approach, i.e. yellow over red on a 2-arm automatic.

So, signal systems are interesting!

Jim Gerofsky

 >> Right, Jim!

Now, to answer that question.  The "Approach Slow" indication is used to 
govern the approach to a slow speed (15 mph) route with the interlocking 
home signal indicating "Clear Slow."  The  Erie did not have a "Slow 
Approach" indication, although some other railroads did.  "Approach 
Slow" could not be used in the rear of a "Restricting" indication, 
because under the rules, a train operating at Restricted Speed had to be 
able to stop short of a train immediately past the signal.  "Approach 
Slow" advised the train that it could pass the next signal at Slow 
Speed, which is not the same as Restricted Speed.  In order for a signal 
to indicate "Clear Slow," the track in advance must be circuited to 
detect the presence of a train, and it must be unoccupied.  The next 
signal in advance of a "Clear Slow" must indicate either "Approach" or a 
more favorable indication.  If a Stop, or Restricted Speed, is required 
at the next signal, a "Clear Slow" cannot be displayed.

The correct signal to govern the approach to a "Restricting" signal is 
"Approach," "Medium Approach," or "Restricting."  Only a "Restricting" 
signal, or a fixed signal consisting of a sign reading "End Auto Block" 
or something similar, can be displayed to permit a train to enter 
non-signaled track, either main, yard or siding.

A "Slow Speed" route through an interlocking would be through a turnout 
or crossover with a frog number lower than  No. 15.  No. 10's were 
common on the Erie, with signaled routes over No. 10's very common in 
passenger stations.  The rule of thumb is that the safe diverging speed 
through a unilateral turnout in miles per hour is twice the frog 
number.  The Erie had some No. 24 equilateral turnouts at Howells Jct 
and both ends of OV (Otisville Tunnel) that were in 70 mph territory.  
In those cases, zone speed was permitted over both routes of the 
turnouts, so a "Clear" indication could be used for either route.  Other 
railroads, including NYC and PRR, had a "Limited Speed" defined, for 
diverging movements over No. 20 turnouts.  NYC originally used 50 mph 
for Limited Speed, but found that hard way that it was tearing up the 
railroad, so they lowered it to 45 mph in 1964.  That was another 
refinement that the Erie and Lackawanna didn't need because train speeds 
and traffic density didn't justify the added expense.

Here are the Erie definitions:

RESTRICTED SPEED--Proceed prepared to stop short of train, obstruction, 
or anything that may require the speed of a train to be reduced.

SLOW SPEED--Fifteen miles per hour unless otherwise provided.

Now, for approach lighting on semaphore signals.  I don't have a 
definite reference for the Erie, but it was common in the "old days" to 
power those signals with primary batteries, which generated their own 
power with no outside source.  The signal maintainers had to continually 
replace the acid and electrodes in those batteries, so it was important 
to conserve electrical energy as much as possible.  It was usually 
cheaper to put an approach lighting relay in a semaphore system than to 
pay for the additional battery maintenance that would be needed for 
continuous lighting.

When searchlight or color light signals were installed, they usually had 
AC power provided in the pole line, with rectifiers at each signal 
location to charge a secondary battery that floated on the power to the 
lamp and control circuits.

In figuring out the logic in signaling, it helps to understand that, 
generally, a signal will display two essential elements of information.  
First, "May I pass this signal, and if so, at what speed;" and Second, 
"At what speed may I approach the next signal."  Signal engineering 
always assumes that a train will have no preview of the signal, even 
though a preview is actually necessary just for the engineman to see and 
comprehend the signal.  Stopping distances and signal spacing are 
determined from the immediate location of a signal, and not from some 
point in the rear of the signal where the engineman would otherwise be 
expected to see it.

Just a few more thoughts for the pot on this interesting (I hope) 
discussion.

Gordon Davids


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