The Chain+Level - A True Alternative to Total Stations for Topographic Surveys

Surveying elevation profiles or road sections 5 times faster than with a total station, without even cutting trees? It is easy with the Chain+Level, the productivity booster! The Chain+Level is a true alternative to total stations and GPS (Global Positioning System) used to measure the difference of elevation between two points in woody or hilly areas. The Chain+Level gives additional flexibility to do fast and inexpensive topographic surveys in such environments.

"The Fastest Way to Do Surveys Without Visual Contact in Woody Areas and Forest Roads."

Advantages of the Chain+Level over Total Stations

• No need to cut vegetation means time and cost savings.
  
  
• Field applications so far indicate a productivity improved by 200 to 500% compared to total station surveys as there is no permit nor line cutting required.
  
  
• Faster surveys, less errors as the storage of the co-ordinates are transferred from the optional datalogger to the office computer at the end of each day.
  
  
• The high precision of the elevation obtained (Z) from the Chain+Level can be combined with the co-ordinates (XY) from a relational GPS. With the Chain+Level, one can level between benchmarks spotted with a high-precision GPS or total station at every kilometre or so.
  

C+L Standard Components	C+L Electronic Notebook

Successful applications

• Staking out longitudinal profiles and measuring cross-sections on roads, power lines, etc.
  
  
• Staking out flood basins, such as for hydroelectric dams.
  
  
• Topographic surveys, especially in woody areas.
  
  
• Geophysical surveys: gravity, seismic, electromagnetic, etc.
  
  
• Drill hole collars and geological section surveys.
  
  
• Geophysical surveys: gravity, seismic, electromagnetic, etc.

The new GDD Chain+Level is lighter, up to 3 times more accurate, immune to temperatures fluctuations, and has been built with applications software such as gravity, profiles and probing. Profile readings are memorized and transferred daily to a PC.

C+L debubbling vacuum pump	C+L aluminium sensor rods

Using the Chain+Level, some field crew like Geosig Inc., have been able to cut gravity survey cost substantially while keeping a good precision per station. For example, in October 2005, Geosig Inc. reported that on traverses of 3 to 4 km, the error per station was less than one cm.

GPS can loose satellite signal over significant daytime periods, especially in northern areas because of the poor satellite coverage, the craggy areas and forest cover. This can reduce GPS crew survey time by more than 50%. GDD Chain+Level is not affected by these inconvenients, neither by water, snow, fog, etc. Therefore, the Chain+Level provides lower costs with comparable precision to a high end GPS configuration.

Gravity operator	Chain+Level operator

Geosig Inc. gravity crew at work with the latest GDD gear
Labrador, Canada, 2005

The Chain+Level is really fast and simple to operate

The GDD Chain+Level consists of a digital reading unit and two pressure sensors connected by a flexible 25 or 50-meter chaining cable containing a special fluid. Three other sensors measure temperature and density variations in the fluid. Readings are quick, and the meter indicates true elevation differences with high precision at any outside temperature.

The sensor rods at each end of the cable are placed on the points to be measured. The digital reading of the difference of elevation, V, is obtained instantly just by pressing one key. The rods are then transferred to new positions to read successive differences in elevation. No visual contact is ever needed between the points to be measured.

Road survey crews report that they are at least three times
more productive with a GDD Chain+Level™ than with a total station.
They especially like the fact that it is so simple to operate.

Road survey crews report that they are at least three times more productive with a GDD Chain+Level than with a total station. They especially like the fact that it is so simple to operate.

The operator presses the slope distance button and is given the exact slopedistance (S) he must chain for a preset horizontal interval (H). The slope distance (S) is chained. The two stations are now exactly H meters or feet apart horizontally. The pickets are driven in or a reference point is marked on the ground. With sensor supports on top of the pickets, the exact elevation difference between the two points is read instantly by pressing the vertical distance button.

Whether it is used by itself or jointly with a GPS or a total station, the Chain+Level is designed to suit your own requirements. You just have to choose between these options:

• The reading unit with a cable (the easiest way to use it)
  
  
• The reading unit with a cable, plus the optional datalogger and the GDD Chain+Level software enabling the recording and transferring of data to a computer in ASCII format at the end of the day. The ASCII format is a universal standard.

Precision

For a one-kilometer profile, typical closure errors are less than 10 cm. The error on each station is less than 2 cm (0.1 foot).

For sections or profiles, the Chain+Level can measure a difference of elevation of ~15 meters in millimetres in a single reading with a precision of 0.2 %. The reading precision gives an immediate feedback of the reading quality to the operator.

The reading unit with a cable, combined to the optional datalogger and the Multi-Carnet software for advanced surveys, allow to relate total station data or transform the data obtained to make them compatible with any COGO software. Users can use the datalogger with the Multi-Carnet software, choose the Chain+Level driver and later change the driver to work with almost any total stations on the market.

SPECIFICATIONS

Standard Components

• Reading unit with leather case and cable
  
• Battery charger (110 VAC, 220 VAC)
  
• Extra bottle of fluid for the cable
  
• Spare screws and screwdriver
  
• Springs for gravimeter table
  
• Instructions manual
  
• Calibration tape
  
• Shipping case

Options

• 6 aluminium sensor rods
• Portable debubbling vacuum pump (User's Guide-see appendix 1)
  
• Extra 25 or 50-m cable (100 or 200 ft)
  
• Special cable lengths available upon request

Measurements

• Range: ± 10 m (± 30 ft)
  
• Reading resolution: 1 mm (0.005 ft)
  
• Calibration stability: ± 0.2% (less than a 2-cm error per 10-m elevation)
  
• Typical closure error (sigma): <10 cm (4 in) on a 1-km (3/4 mile) traverse
  
• Elevation precision per station: <1 cm (0.04 in) on a 1-km (3/4 mile) traverse
  
• Tested temperature range: -40°C to 40°C (-40°F to 104°F)

Reading Unit

• Size: 25.7 x 11.1 x 12 cm (10 x 4.25 x 4.75 in)
  
• Weight:
  - 1.1 kg (2.4 lb) with AA batteries
  - 2.5 kg (5.5 lb) with 12-V battery
• Case: Aluminum, shock resistant
  
• Power source: 3-6 rechargeable AA batteries or 12-V rechargeable battery
  
• Usage: 1.2 watt (100 mA)
  
• Battery life: Up to 12 hours
  
• Battery charger: 110 VAC, 220 VAC

Cable

• Standard lengths: 25 m and 50 m (100 and 200 ft)
  
• Weight: 2 kg / 25 m (5.6 lb / 100 ft)
  
• Chaining cable: Robust, shock resistant, waterproof
  
• Cable chained: At every 0.1 m (4 in)
  

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Instrumentation GDD Inc.
860 boul. de la Chaudiere, Suite 200
Quebec (Qc)
CANADA
G1X 4B7
Phone: +1 (418) 877-4249 - Fax: +1 (418) 877-4054
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