Close Interval Survey Planning
Counts stations, data points, wire-spool setups, and field days for a close interval survey.
Example
You enter
- Survey length (miles) 10
- Reading interval (ft) 2.5
- Readings per station (2 for on/off) 2
- Usable wire spool (ft) 5000
- Crew production (miles per day) 2.5
- Seconds per reading 1.5
- Crew day (hours) 8
- Test station spacing (miles) 1
- Alternative interval (ft) 5
You get
- Stations read 21,120 stations, 42,240 potentials
- Data points 42240
- Against test stations alone 11
- Readings between stations 21109
- Wire spool setups 11 reconnections to a test station
- Field time 4.0 crew-days
- Actual reading time 8.8
- Meter busy (%) 27.5
- At the alternative interval 10560
No published worked example is on file for this calculation. It is checked against a hand-worked derivation of its method and an independent reference test.
Details, formula, and sources
ScopeTen miles at 2.5 ft is 21,120 stations against 11 test stations, and the meter is busy only 28% of the field time. Doubling the interval steps over half the holidays.
Formula or tablestations = length / interval, doubled for on/off; spool setups = length / spool, rounded up; field days = length / production rate.
Source and editionNACE SP0207 (now AMPP) governs close interval survey practice.
Free accessPublic planning arithmetic.
What governsEstimate. AHJ and licensed professional govern.
API field namessurvey_length_mi, reading_interval_ft, readings_per_station, spool_length_ft, production_mi_per_day, seconds_per_reading, crew_day_hours, test_station_spacing_mi, alternative_interval_ft, reading_count, data_points, test_station_readings, readings_between_stations, spool_setups, field_days, reading_hours, meter_busy_pct, alternative_reading_count
- Field time scales linearly with interval here, which overstates the saving since walking does not shrinkspec-v1772 caveat
- Crew day entered; the meter-busy share depends on itfield practice