--- Carleton MacDonald <[EMAIL PROTECTED]> wrote:
>The Canadian railroads use mileposts only because the United States
>railroads still do, and there is much cross-border travel (and
>cross-border ownership).
I suspect that's far from the entire reason. Once mile posts have
been erected, they function as known points in a coordinate sytem
extending along the rail line. The location of culverts, buildings,
water, sewer and other pipes, etc. are recorded by refering to mile
posts.
Certainly there are reasons one might wish to alter the location of
mile posts. The original surveyor may have erred, many "mile posts"
are not 1 mile apart. Over the decades, small changes in track
location may alter the length of track between two points. One may
wish to express distance in units of furlongs, or kilometers, or
thousands of yards.
But to tear up the existing marks is risky. Somewhere there is a
drawing of a culvert which notes that it is is 528 feet west of mile
post 512. There is no note anywhere which says "mile post 512 is
mentioned on drawing C-59673."
Thus if M. P. 512 is removed, there is no cue to revise drawing
C-59673 or any others which refer to that M. P. But lacking that mile
post, that drawing and many others are left floating in space.
I suppose one could prepare a large book with entries like
"References to mile post 512, made before Feb. 23, 2003 are to be
taken to be references to a point 440 meters west of K. P. 879".
Thus, to find the culvert in question, one need only:
1. Look at the original drawing, note the mile post reference.
2. Using "the book" convert M. P. 512 to K. P. 879 + 440 meters.
3. Convert 528 feet to 162 meters.
4. Add 162 + 440 = 602 meters.
5. Note that the culvert is 602 meters west of K. P. 879.
At this point, after some fooling around in the engineering records
and some calculations on the back of an envelope, the person making
the inquiry is as well off as if the mile posts had simply been left
in place, however offensive that may be to fans of the metric system.
The point is that any massive re-definition of known points along the
railroad would have implications far beyond the expense of setting up
new markers. I suspect the folks in the engineering departments of
the Canadian railways know that.
=====
Bob Netzlof a/k/a Sweet Old Bob
This is from a railroad-oriented list, wondering why Canadian railroads still use mileposts. cm
