[N&W] Rock Slide Detector Fences
nw-mailing-list at nwhs.org
nw-mailing-list at nwhs.org
Mon May 31 14:37:07 EDT 2004
ROCK SLIDE DETECTOR FENCES
Some years ago while visiting a model railroad, one
of the members asked me about slide detector fences.
Locked in a not unusual model railroad mountain
predicament, the modeler was faced with very steep
-- almost vertical -- high embankments paralleling
his nicely curving mainline.
Rather than mumble onward, I showed him several
slide detector fences in N&W and Clinchfield photo
books. For a modeler, I thought this was perfect as,
for me, there is no way better to model than directly
from proto photos.
And he did.
I was back there a month later and his slide fences
looked excellent, very close to the photos. Some were
in place while several others were formed and just
about ready to install. Nice job!
Well, not so nice.
I dropped in a few weeks later and about lost my lunch. All the slide
fences were in place and sceniced -- they looked great -- but between the
fences and the steep walls, the modeler had poured in enough rock scraps to
fill in the space about half way up his rock detector fence and all along
the full length of his excellent detecting wire web.
Whaaaa?
The modeler was thrilled with his work and merrily showed off all the
details, even including "... all the rock that over the years had
accumulated ..." behind the fence. He said he believed such a rock pile was
prototypical.
Hummmm ...
So, I asked him to show me a proto photo of slide detector fence holding
back that much rock. Of course, no such photo came to the limelight.
However ...
The situation stimulated an excellent debate (in which I mostly did not
partake) and which would have made cable TV's "Hardball" sound wimpy. There
were several interesting points made ... or should I say, powerfully
elucidated! The spit was flying ...
Some swore the rock pile was realistic. Others made funny noises.
Associating in favor of the rock pile theory, one said that railroads used
the fences to keep the rocks off the tracks ... And that no one ever
cleaned out the rock piles behind the fences.
One fellow thought that to key the sensor a rock or slide had to break a
wire. Another said the rock hit the wire and it pulled a spring that yanked
a solenoid and set off the sensor. Most really didn't know.
The voting was about even regarding the output. Maybe half said that when
hit the fence sensors triggered only red lights on the two nearest signals
guarding either direction through the slide area. But then, the other half
felt that the sensors sent a specific "fence-been-hit" signal direct to the
dispatcher. Futhermore, the other half didn't know this one either.
The fence takes a slant near the top and there were several opinions as to
why the slant and which way it slants -- toward or away from the track --
photos be damned.
There was more, such as how the fences look on each end, how many types of
sensors a given fence might have, how strong is the fence vs. the size of
the rocks that might fall, and are the fences typically painted and what
color? I'm sure there was more, but I'll cut it here so I can make my point
before I lose everyone.
The modelers' discussion in reality was great. It brought up a variety of
railroad aspects that some had never heard of and in which virtually all
had some interest. I mean, this is the way railroad knowledge and interest
gets advanced. In spite of the shouts, the defending of turf and even the
volleys of misinformation, the debate was great.
Years later we have email lists such as the one we are on now and on which
we can carry forth with the same sort of debate ... For the most part, sans
the red faces and with time to do a bit of research before opening one's
mouth ... Errrr ... Hitting the send button.
What I'd like to do is to spread that debate here amongst this group. As
you read the material above you likely had an opinion or two on several of
the differing points. And I'm hoping you'll take the time to offer here
your knowledge and questions for both the modelers amongst us who really
would like to get it right and for the 1:1 fans here who just like the warm
fuzzies of learning more about real railroading.
What do you all know about slide detector fences? Among several such fences
that I've seen are those up on the bluffs north of Clinchfield's Copper
Creek Viaduct (or was it a bridge? ... or a trestle?) and beside the
Norfolk & Western's Pokie mainline as it climbs the miles leading to
Maybeury (is that Ennis?). I only presume that the Virginian and B&O had
the rock stopping fences, too. What do you know?
Frankly, I've never seen a slide fence back filled with rock. I've never
seen anyone carting away all the fallen stones. I've never seen a train
stopped by a red board induced by a slide fence. Heck ... The ones I saw
... Well ... They were just standing there minding their own business when
I saw them.
Sooooo ... What do you guys know? Spill your guts on this one ... Let it
all hang out. What's the low down on railroad slide detector fences?
As a kickoff, why not check out this link to view a "Standard Rock Slide
Detector Fence (new type)" of May 8, 1975, on the D&RGW. But please do not
limit yourselves to modern era slide fences ... This is an "era limitless"
experiment.
Click here:
http://users2.ev1.net/~swmeier/DRGW/MOWBooks/1966Book/images/Page%20156.1.jpg
And here's a definition I found. Do you all agree with it? Does someone
have a better or corrected definition?
>>>>>
What is a slide detector fence?
To prevent train accidents due to falling rocks or earth slides in hilly or
mountainous regions, electrically charged wire fences are made to serve as
detectors. If a falling rock or an earth slide breaks one or more of the
wires in the fence, a relay is released and "stop" signals are set up to
halt a train approaching from either direction.
<<<<<
Anyway, tonight I was thinking, "The Cubs lost ... Might as well do slide
fences." What do you say?
Thanks and later ... Bob Loehne
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