The drafting instructions in this chapter are for the purpose of standardizing the preparation of drawings, simplifying various details of the work, and securing the greatest possible uniformity in appearance, size, and style consistent with the subjects and purposes involved, all at a saving of time and effort. All work should be done in conformity with these instructions, and with those contained in "American Standard Drawings and Drafting Room Practice," ASA Z14.1-1946 of the American Standards Association, so far as the latter are applicable and not in conflict with the instructions outlined in this chapter. Administrative procedures concerning signatory authority, publication, distribution, transmittal, titling, numbering, and revising of drawings are contained in Chapter 2.5 of Volume X. Instructions regarding the preparation of special maps are given in Part 5, Special Surveys and Mapping, and Part 6, Budget Maps and Charts, of Volume VIII.
.2 As a drawing or a map is a means of conveying and recording information,
the information placed on the drawings or maps should be not only correct,
but so arranged and referenced that the drawing or map can be easily and
clearly interpreted. Construction drawings should be complete as to all dimen-
sions and sizes of materials without reference to the specifications. Finished
drawings should be so prepared that prints or reproductions as well as reduc-
tions to the smaller scales commonly in use will be clear and legible. Careful
consideration should therefore be given to the weights and values of lines and
to the accuracy, style, and position of all notations. Typical illustrations of
drawings are given in Figures 62 through 70.
All unnecessary work, such as the duplication of views and notes, unnecessary details, and ornateness in borders, lettering, north points, meridians, and other features, should be avoided. Simplicity should be practiced in every detail in inking tracings; lettering should be plain and simple; and notes should be limited to those required for accurate interpretation. Lettering standards for drawings are prescribed in Figures 6, 7, and 8.
All original drawings, unless otherwise specifically directed by the supervisor, should be made on vellum or similarly translucent paper; all lines should be made in pencil, clear and sharp, and of sufficient width and density to insure clear reproduction.
PREPARATION OF DRAWINGS AND TRACINGS
.5 The orientation of maps and drawings should accord with the following principles:
A. General location maps, vicinity maps, and all similar maps should be
oriented with the north to the top of the page. This orientation may be
changed in special cases, where the area to be mapped is of such a nature
that the following of this rule would produce an unnecessary amount of
blank space on the map. If the north cannot be shown toward the top, it
should preferably be toward the left side of the map. Full-headed arrows
of simple but distinctive design should be used to indicate the true meridians
(see Figure 11). The magnetic meridian should be designated by a half-
headed arrow joining the meridian arrow at the proper angle of magnetic
declination, with the angle designated. The long dimension of the map
should preferably be from left to right, rather than from top to bottom.
Maps should show the direction of the true meridian, and all legal sub-
divisions or coordinate lines should be referred to fixed and readily
identifiable points, such as section or quarter-section corners.
Maps showing the location of dams or other important structures covered
by plans and specifications should be prepared in such detail that the loca-
tion can be shown with respect to section, quarter section, township, and
range lines, as well as lines of the coordinate system of the detailed topo-
graphic survey. All location maps should show two latitudinal and two
GENERAL DRAFTING REQUIREMENTS
PREPARATION OF DRAWINGS AND TRACINGS (Continued)
longitudinal lines unless the area involved is minute. In the latter case one latitudinal and one longitudinal line are sufficient. The most important sources from which a map is compiled should be stated under the heading of "Notes" in the lower left-hand corner.
B. Detail maps, plans, and layout drawings for dams, reservoirs, and other
major structures should be oriented so that the direction of streamflow is
toward the top or the right side of the sheet. A north-point arrow should
be placed on all such drawings and streamflow arrow should be included
wherever applicable. Borrow-pit maps which are tied to the dam-site
coordinate system should also be shown with the same orientation. All
sections paralleling the direction of streamflow should be drawn with the
direction of flow toward the right, unless a particular detail cannot be
properly illustrated with such a section.
C. Vertical sections and elevations normal to the direction of flow of a stream
or canal should be shown looking downstream, unless such arrangement
would fail to show the feature intended by the section. Stationing or profiles
should increase from left to right and should increase downstream for irri-
gation canals and upstream for drainage canals. Reference lines should be
stationed downstream in the direction of flow, and reference lines normal to
the direction of flow should be stationed from right to left so that cross
sections from such lines will be properly oriented. Drawings of railroads
or highways should follow the stationing of existing railroads or highways
into which they tie. If they do not tie into any existing highway or railroad,
a stationing should be adopted to suit local conditions.
D. Graphs or charts which are likely to be reduced for inclusion in reports with the top of the drawing becoming the binding edge, should have subtitles at the right or left margins made to read downward on the original so that they will be properly oriented when reduced. (See Paragraph 1.23.)
For uniformity and convenience in filing, it is desirable that drawings conform to definite size standards. The preferred standard over-all size for all regular design, specification, and construction drawings is 21 by 36 inches, with the marginal line or border 3/4 inch from the outer edge at the top, bottom, and right sides, and 1 inch at the left side (see Figure 1).
A. If necessary in special cases, and if approved by the head of the division or
section, the length of the drawing may be increased up to a maximum over-
all length of 60 inches; but it should be borne in mind that such drawings
must be folded once for filing which makes this size objectionable. Standard
sizes of drawings are indicated in Figure 1. The maximum over-all size
of drawings that can be filed conveniently without folding is 28 by 38 inches,
and it is therefore highly desirable to keep all drawings within this size.
B. The sizes of drawings most frequently used are 8 by 10.5 inches or letter
size, 10.5 by 15 inches or 18 inches, 16 by 21 inches, 21 by 29 inches, and
21 by 36 inches. All drawings should conform to the standard sizes if
at all practicable; in exceptional instances it may be necessary to depart
therefrom. The minimum size that will satisfactorily meet the requirements
should be used. The use of large sheets only partly filled with drawing
matter should be avoided. The scales used should be as small as will satis-
factorily meet requirements. In choosing between the 21- by 29-inch and
the 21- by 36-inch sizes for drawings that are to be reduced to letter size
(8 by 10.5 inches) for reports, preference should be given to the 21- by
29-inch size if feasible, because this size can be reduced almost exactly
to a letter-size sheet. Use length increments of 6 inches for drawings
larger than 21 by 36 inches.
Scales of drawings will vary with the size and character of the feature or the degree of detail to be shown. Scales should be selected with care in order to
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