How often should you check a dumpy level?

How often should you check a dumpy level?

We would recommend that site staff should check a dumpy level for accuracy every week.  This site check should also be logged and stored with the Calibration Certificate for the dumpy level.  Any deterioration in the accuracy of the dumpy level can then be easily identified and the dumpy level can be serviced and calibrated.

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Why you should check your dumpy level weekly.

Using any piece of equipment that you haven’t checked could lead to disaster.  Using a dumpy level that hasn’t been checked can lead to a costly mistake.  Take the case of a site engineer working on a new proposed surface water drainage network for a new proposed access road.  After setting out the new manhole positions along the new proposed road, the site engineer proceeded to work out profiles for the drain runs.  Each time he set up his dumpy level he was next to the downstream manhole and took readings to the upstream manhole.  But because he hadn’t checked his dumpy level, he didn’t realise that it was falling by 20mm over 30m.  He also didn’t close his levelling run so had no other clues as to the accuracy of his results.  As the drainage works progressed, the pipe runs were installed lower than the design levels.  The mistake was only noticed when the cover and frames were being installed and the drainage crew were using more raising pieces than expected, and in the worst case an extra manhole ring was needed to be installed. 

All of the above could have been avoided if the site engineer had performed a two peg test weekly, or if he had performed the levelling exercise properly and closed his levelling run.

How to check a dumpy level?

A dumpy level is checked for accuracy by carrying out a two peg test.  Here is a straight forward, easy to follow guide on how to perform a two peg test on a dumpy level.  This is straight forward and can be done on any site by any competent surveyor or engineer.  This two peg test is for use on any dumpy level like the Topcon AT-B4A. 

Get your dumpy level calibrated.

If, having checked your dumpy level and you find that it is not giving the accuracy required then you should get it calibrated.  Your local preferred survey supplies specialist will offer to service, adjust and calibrate your dumpy level.  This will be more cost effective than continuing to work with a rotating laser giving out poor inaccurate levels.