purpose of the map. The following guidelines suggest
the nature of typical map specifications.
A map should present legibly, clearly, and concisely
a summation of all information needed for the use
intended, such as planning, design, construction, or
Topographic maps for preliminary site planning
should preferably have a scale of 1 inch = 200 feet and
a contour interval of 5 feet. These maps should show all
topographic features and structures with particular
attention given to boundary lines, highways, railroads,
power lines, graveyards, large buildings or groups of
buildings, shorelines, docking facilities, large rock
strata, marshlands, and wooded areas. Secondary roads,
small isolated buildings, small streams, and similar
minor features are generally of less importance.
Topographic maps for detailed design for
construction drawings should show all physical
features, both natural and artificial, including
underground structures. Scales commonly used are
1 inch= 20 feet, 1 inch= 40 feet, and 1 inch = 50 feet.
The customary contour interval is 1 foot or 2 feet,
depending on the character and extent of the project and
the nature of the terrain. Besides contour lines, show any
spot elevations required to indicate surface relief.
Additional detail features that are usually required
include the following:
1. Plane coordinates for grid systems, grid lines,
and identification of the particular system or systems.
2. Directional orientation, usually indicated by
the north arrow.
3. Survey control with ties to the grid system, if
there is one. This means that the principal instrument
stations from which details were located should be
indicated in a suitable manner.
4. All property, boundary, or right-of-way lines
5. Roads and parking areas, including center-line
location and elevation, curbs, gutters, and width and
type of pavement.
6. Airport runways, taxiways, and apron
pavements, including center-line locations with profile
elevations and width and type of pavement.
7. Sidewalks and other walkways with widths and
8. Railroads, including center-line location,
top-of-rail elevations, and any turnouts or crossovers.
9. Utilities and drainage facilities, such as gas,
power, telephone, water, sanitary sewer and storm sewer
lines, including locations of all valve boxes, meter
boxes, handholes, manholes, and the invert elevations
of sewers and appurtenances.
10. Locations, dimensions, and finished floor
(usually first floor) elevations of all structures.
Describe topographic control.
Assume that you are establishing the primary
vertical control for a topographic survey. The
terrain is level and the desired contour interval
is 1 foot. What is the maximum error closure?
Can you use stadia leveling to achieve this error
You are detailing a point from a primary control
station that has a known elevation of 174.3 feet.
Your height instrument (h.i.) above the station
is 5.6 feet. After reading a stadia interval of 2.45,
you train the center hair of your telescope on the
rod to match your h.i. and read a vertical angle
of +6 °36t. If the stadia constant is 100 and the
instrument constant is 1, what is the (A)
horizontal distance, (B) difference in elevation
and (C) elevation of the detail point? (Use the
exact stadia formulas.)
Your transit equipped with a stadia arc, is set up
at point A (elevation = 245.2 feet) and you are
sighting on point B. Your h.i. is 4.3 feet. The line
of sight is at 5.8 on the rod and the stadia reading
is 6.43. The stadia arc has index marks of H = 0
and V= 50. The stadia arc readings are V = 63
and H = 12. Your stadia constant is 100 and the
instrument constant is O. What is (A) the
horizontal distance to point B and (B) the
elevation of B?
Define contour interval.
On a topographic map, when a contour line
closes on itself, what is being portrayed?