Staff errors in and the adjustment of ordinary levelling runs

Abstract

Even though ordinary levelling with wooden, fibreglass and aluminium staffs is carried out on a daily basis, few observers are aware of the relatively large errors of these staffs and fewer still employ adjustment procedures for the levelling data which offset these errors. Predicting the graduation and expansion errors of ordinary staffs and adding systematic refraction errors, the likely maximum scale errors are estimated as 11 mm per 10 m height difference. Formulae and numerical examples are given for three different adjustment methods. Their suitability is discussed and their results are compared.