This comes from the formula provded by the standard setting body or authority It is set by the authority. Different bodys may have different standards or formulas . This particular one is a common value for 3 rd order levelling here in New Zealand. You will see in oter videos where I have used a different forumla based on the umber of set ups tis is more suitable for small jobs with short runs.
The value may vary depending on the authority responsible for the levelling. Here in NZ LINZ has an order specification for the levels they administer however some other authority can specify there order if they wish. It is therefore important that you clearly define what specification you are working to and check that it agrees with your clients requirements. As a general rule I would stick with national standard setting bodies.
could you please explain from where you got +- 7mm
This comes from the formula provded by the standard setting body or authority
It is set by the authority. Different bodys may have different standards or formulas . This particular one is a common value for 3 rd order levelling here in New Zealand. You will see in oter videos where I have used a different forumla based on the umber of set ups tis is more suitable for small jobs with short runs.
Second order is plus or minus 6 right?
The value may vary depending on the authority responsible for the levelling. Here in NZ LINZ has an order specification for the levels they administer however some other authority can specify there order if they wish. It is therefore important that you clearly define what specification you are working to and check that it agrees with your clients requirements. As a general rule I would stick with national standard setting bodies.