Model Forum / General / Railroads / March 2007

Mark Mathu spake thus:

I'm looking at the March 2000 /Mainline Modeler/ article now, and I
notice that the article mentions no dates. It does say this:

  To minimize the accident potential [from rockslides], the railroads
  initially had a track walker physically walk, or ride the tracks on
  a section car, to make sure the line was clear and free of any
  obstructions before a train was scheduled to pass over that section.
  [...] Track walkers were eliminated many years ago due to the expense
  of labor, and were replaced by rock slide [detector] fences.

Unfortunately, the author give no clue as to how long ago "many years
ago" was. The article does, however, have very good detail about the
detector fences. My guess is that they'd be perfectly appropriate for
the period you asked about, as they're simple mechanical-electrical
devices which work simply by wires being either broken (open circuited)
or shorted when rocks fall on them.

The example he gives (with photos) is at Lava Hot Springs, Idaho.

*snip*

http://www.puckdroppersplace.us/other/100_1722.JPG [850k]

This is a picture that I took while riding on the Royal Gorge railroad in
Colorado.  This may provide you with a few ideas of how they did it.  The
picture was taken in 2006.

Puckdropper

On Thu, 22 Mar 2007 23:21:16 -0500, Mark Mathu posted in article
<4603561d$0$4910$4c368faf@roadrunner.com> ...

The 12/92 MM article is a Hundman ramble accompanied by three rather
dark 1986 photos of a detector fence erected along the N&W near
Bluefield, WV:
    "Ordinary farm fencing of the woven 'hog-tight' type is erected
    panel above panel on suitable poles to afford a yielding
    interceptor of rocks, ice, or soil which might fall from the
    cliffs to the tracks.  Supported by messenger wire between
    poles, each of the vertical panels is fitted with circuit
    breakers at intervals, which open when any appreciable pressure
    is exerted against the fence."
The poles in the photos appear to be "T" section steel fence posts
that extend about 12-15 ft vertically, then bend at about 15-20 deg
from vertical toward the track for another 3-5 ft.  The mesh fencing
is barely visible, the messenger wires are not.

The 3/00 MM article shows two UP designs as installed in Idaho and
Montana, one very similar to that shown in the MR article and the
other similar to the N&W fence.  The UP sprung fence includes an
additional sprung section above a ground-level section.  Both UP
styles are supported by round wooden poles;  photos show the pole
heights range from about 10 ft to about 30 ft.  No photo dates are
given.

I recall seeing both general types of detectors (sprung and non-
sprung) on the GN's Oroville Branch (west side of Columbia River,
north from Wenatchee to Chelan) in the 60s and 70s, at a few locations
where rock joints on the cut (west) side dipped toward the tracks.  
Along much of that route detection wasn't necessary, because US97
is/was between the tracks and cliffs and caught most of the debris.

The GN used the non-sprung type in the 50s to detect slides/slumps
adjacent to silt/clay cliffs in northwestern Seattle.  Climbed it
several times, never could break the circuit...