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Accuracy and completeness tests of maps are ‘accomplished by field surveys 
and are performed by the contracting authority with its own survey parties or 
by the engineering firm engaged to make the basic project control surveys and 
compile the maps. When the latter procedure is followed, the contracting 
authority has an aerial surveys engineer present to designate where the survey 
measurements should be made for the testing. This testing procedure is 
described in the following paragraphs. Once the field notes of the test sur- 
veys are completed, the aerial surveys engineer takes the notes immediately 
and utilizes them, as also subsequently outlined, in completing the accuracy 
tests of the maps. 
To determine the accuracy of contours, a test traverse is staked on the 
ground which originates and closes on station markers of basic control surveys 
for the project. The survey closure of this traverse may not be less than the 
accuracy required in such basic control surveys. A sufficient number of con- 
tours are crossed by the traverse to constitute a reliable test. Then the 
accuracy of the contours is determined by spirit-level measurement of the pro- 
file of the test traverse. Elevations are measured at all stations 100 feet 
apart in foot system and 20 meters apart in metric system, and at all changes 
in ground slope between each stationing point. The closure of level circuit, 
in which the profile is measured, should not be less than the accuracy required 
in basic control surveys for the project. The survey-measured traverse is 
accurately plotted on the maps. The profile measured on the ground along this 
traverse is compared with profile plotted from contours of the map where the 
test traverse crosses the contours. 
The positions of planimetric features are accurately measured by ground 
surveys, using as an origin station markers of the basic control and/or the 
nearest test traverse. The plane coordinates of each feature being tested 
are computed from the ground survey measurements. The plane coordinates of 
each feature in its plotted position on the maps are determined. In determin- 
ing such coordinates, appropriate interpolations are made between the coordi- 
nate grid lines whenever the map distance between any two lines is not equal 
to the grid interval because of shrinkage or enlargement of the material on 
which the map copy is printed. These separate positions for each feature 
being tested are compared by their plane coordinates as ascertained from field 
measurements and from interpolations on the map. 
As to the completeness of maps, the photographs are examined stereoscopic- 
ally and details are determined therefrom which should be delineated on the maps. 
Such details are compared with those on the maps. By this procedure, the ade- 
quacies in completeness of the maps and places where field editing is essential 
are noted. At this point, decision is made as to which maps are acceptable and 
which should be rejected. 
Accuracy and completeness tests of the maps are also made by photogram- 
metric methods. These methods are advantageous for ascertaining maps that can 
be accepted without further testing and maps which will require testing by sur- 
veys on the ground before they are accepted or can be rejected. Therefore, 
they are, in effect, an excellent substitute for random sampling and serve to 
designate specifically which maps should be field tested and where on the maps 
the tests should be made. An independent map testing agent specifically 
employed for such purposes by the contracting authority, or a special unit of 
that authority which is qualified, equipped, and assigned to the work may per- 
form the photogrammetric testing of maps. Specifications are required for this 
work, as for the mapping when done under contract by consultants. 
The map testing agent or special map testing unit is supplied with all 
materials and data used for the project mapping, such as photographic trans- 
parencies, both basic and supplemental horizontal and vertical control, map 
manuscripts, and copies or originals of the finished maps. The working accu- 
racy of the map testing agent or unit and/or the reliability of the photogram- 
metric instruments being used in the testing, and of materials and data fur- 
nished for such work, are ascertained by designating a reasonable number of