Survey Grades

ASF Cave Survey and Map Standards

Ken Grimes, 1 March, 1997 ASF Survey Commission

Table 2.1: Survey Grades
Table 2.2: Map Detail Grades
Table 2.3: Qualifying Suffixes

Table 2.1 Survey Grades

GRADE	TYPICAL INSTRUMENTS AND METHODS	OBSERVATION PRECISION		EXPECTED ACCURACY	COMMENTS
GRADE	TYPICAL INSTRUMENTS AND METHODS	ANG.	LIN.	EXPECTED ACCURACY	COMMENTS
0	Ungraded	-	-	-	-
1	Sketch or diagram from memory. Not to scale.	-	-	-	-
2	Map compiled from notes, sketches and estimates of directions and distances made in the cave. No instruments used.	-	-	-	If Grade 3 un-attainable
3	Significant directions measured by compass. Distances measured by chord (e.g. waistloop, safety line, ladder) of known length, or by careful pacing or body dimensions. Significant slopes estimated.	5°	0.5m	10%	Preferred grade for quick surveys
4	Compass and tape traverse, using deliberately chosen stations (not necessarily permanently marked, but preferably indicated by natural or artificial marker). Distances by tape, marked cord, or rangefinder. Slopes estimated by simple clinometer or horizontal and vertical components of line measured.	2°	0.1m	5%	If Grade 5 un-attainable
5	Compass and tape traverse. Directions by calibrated compass (e.g. liquid-damped prismatic or semi-supported Brunton). Vertical angles by calibrated Abney level or similar clinometer. Distances by metallic or fibreglass tape, or tacheometry.	1°	5 cm	2%	The preferred minimum grade. Highest possible grade if magnetically unchecked.
6	Traverse and/or triangulation using calibrated, tripod-mounted instruments for directions and vertical angles (e.g. forestry compass). Distances by calibrated tape or precise tacheometry, or subtense.	15'	2 cm	1%	-
7	Controlled traverse and/or triangulation using small theodolite (e.g. Wild T12 or T0, adjusted forestry compass with vernier) for directions and vertical angles. Distance by calibrated steel or fibreglass tape.	5'	1 cm	1/1000	-
8	Conventional theodolite traverse and/or triangulation conforming with requirements for acceptable cadastral survey accuracy. Directions and vertical angles by glass arc theodolite (e.g. Wild T1). Distances by standardised steel tape or band or electronic distance meter (EDM). All normal precautions for the elimination of systematic errors should be taken. Levels may be made by differential levelling.	20"	5mm	1/5000	-
9	Precise control traverse and/or triangulation and/or trilateration. Directions and vertical angles by "one-second" theodolite (e.g. Wild T2) with constrained centering. Distances by standardised steel or invar tape or band or EDM. Levels preferably by differential levelling.	1"	0.5mm	1/25 000	-

Table 2.2: Map Detail Grades


GRADE	METHOD
0	Ungraded
1	Sketch from memory. Not to scale but indicating approximate proportions.
2	Map compiled from notes, sketches and estimates of directions and dimensions made in the cave.
3	Map compiled from drawings made in the cave, based on approximate measurements of major details. Lesser details added by sketching and estimation.
4	Map compiled from drawings made in the cave, based on measurements of significant details with respect to surveyed points (usually at least Grade 4). All details of general speleological interest should be shown with sufficient accuracy so as to not be appreciably in error at the mapping scale.
5	As for detail Grade 4, with the addition of significant morphological features and details of primary and secondary deposits.

Figure 2.3: Qualifying Suffixes

SUFFIX	METHOD
A	Suffix the letter "A" if the survey is closed and adjusted.
C	Suffix the eletter "C" if the survey is dependent upon magnetic bearings which have been checked and corrected for the effects of possible magnetic anomalies.
E	Suffix the letter "E" if the survey has been checked and corrected by electromagnetic methods.

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