It was not that long ago, 1959-1960, when Santa Fe built the 44 mile Transcon line change in Arizona. I was one of the engineering party chiefs and we also used transits and levels albeit an upgrade from those mudchicken describes. We also used a 100 foot steel chain and did all of our computations on paper in the field with sine - cosine - tangent - cotangent tables to seconds and to eight decimal places. We built with cuts and fills in excess of 100 feet and through volcanic rock. We built it with maximum grades of 1% and curves no greater than one degree - and the one degree curves had 570 foot spirals. We had to improvise frequently to deal with unusual circumstances but todays Transcon would not be what it is without this major line change.
Yes I would do it all again, Just restore my 27 year old body. It was exhilarating and those of us still left to talk about it do so at every opportunity.
Don't forget the "plane table" instruments for mapping, field books and hard-lead pencils, vellum (high-grade tracing paper) and ruling pens for the topographic mapping and cross-section sheets, and lots of calculation paper and good old-fashioned 'number-crunching" - governed by years of hard-won experience, revealed wisdom, insight, artistry of a sort, and not a little simple genius. Remember, it was indeed the 'rocket science' of that day and age.
In response to Murphy's most recent question: It's a interactive or "trial-and-error" process (Lord, how I dislike that expression - it ought to be "trial-and-adjust" instead) that finds, collects, and analyzes all the data, and finds the perceived optimum solution at the time in detail on paper first. That's much, much cheaper and faster than doing it with earth, iron, and concrete in the field at the site, and possible having to undo or redo some of it later on.
In brief, the process is:
1) Reconnaissance (sp?), a very quick and brief overview of the area to select the best location for the river crossing (expensive at best), and one or more likely good routes on either side of it. Not much detail yet - just "up that valley" or "then through that ridge someplace" - done from horseback, by eye, or with a barometer or handheld sighting level for rough elevations to within 100 ft. or so (kind of like a sextant on a ship) [mudchicken and maybe a few others know I'm using the wrong terminology here, but the right name wouldn't mean anything to most readers].
2) Preliminary route location survey - just rough connecting of survey points at intervals of maybe 1,000 ft. apart, and elevations to within a foot or so at each one. This is to refine the recon survey, and enable choosing the best overall route - e.g., "This route is 5 miles longer thatn the other one, but the summit would be 500 ft. lower, though it would also need a deep cut or a tunnel instead", etc.
3) Detailed or final route locating survey - thorough mapping of the selected route, calculating the curves and grades to the nearest 0.1 ft. (1-1/4" approx.) or 0.01 ft. (1/8 inch approx.) setting centerline stakes at 100 ft. max. intervals, and stakes on each side at the tops and bottoms of the cuts and fills. At this time the exact height of your 20 ft. fill would be known at every 100 ft. "engineering or surveying station" at least. By next applying the railroad's standard earthwork 'template' prism-like shape, then the width at the top, the angle of the side slopes, and hence the width at the bottom, as well as the cross-section area, would all be known or calculated at those same stations.
4) Construction stakeout - unless the change in grade is small (typ. 3 ft. or less), the original centerline and most other stakes will be dug up or buried a few times over, esp. as your 20 ft. fill is mounded up. Typically the contractor's surveyors will keep setting new stakes as the fill gets higher - as well as for the abutments and other key points of the bridge - so that there's always a handy reference point for measuring from for the actual construction folks. When they're done, the fill will be within 0.1 ft. or so of the design elevation, and pretty close to the theoretical prism shape - the railroad's surveyors will measure it and check to make sure before the payment amount is calculated and approved.
This is a just a 'cocktail-party' level summary - multiple books have been written about the whole process. One of the better popular treatments is the chapter about locating engineer Edward Gillette in the 1947 book "The Story of American Railroads" by Stewart Holbrook - see: http://www.amazon.com/Story-American-Railroads-Stewart-Holbrook/dp/B0007DF2DA
- Paul North.
In a case like this, where the west bank of the river would start with a 20' high, built up ROW, I have a hard time visualizing how this would progress. Would they mark the centerline of the ROW, then build up the elevation, correcting as they went up, or were they that acurate in the 3 dimensions to start with?
Thanks to Chris / CopCarSS for my avatar.
They were called civil engineers. They learned math, algebra, etcetera. The did thier own computations and took the time it took to make it happen. Mudchicken listed the mechanical things...but most of all they were men with heads containing brains which did the work. In other words, you do the math and you've done the work. So, go figure.
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Wye Level or Dumpy Level, Vernier Transit, chain, math tables, log tables and possibly a nomograph slide rule.
Horse power, steam power & a lot of enginuity.
Some of these guys would embarrass the h*ll out of some of today's engineers.
(I have a Brass 1873 Gurley Engineer's Transit in my living room, next to BossHen's loom to remind me.)
Somewhere around 1880, a predecessr of the Great Northern built a bridge the Big Sioux River, in Sioux Falls, S.D. It crossed over the top of part of the namesake falls, at a particularly wide spot. The west bank has a long area of built up ROW, to make a smooth transition up the hill of the river valley. In addition, the bridge and the built up ROW are laid out on a curve. Before computers, calculators, satelites, etc... how did they lay this out and build it to the proper proportions?
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