Assessment of Merged Methods of Booking and Determining Reduced Levels (Rise and Fall Methods with Height of Collimation) in a Longitudinal/Profile Levelling Surveying

Basically, booking and determination of Reduced Level (RL) in levelling survey is fundamental in engineering surveying for profile levelling, cross-sectional levelling, establishing vertical controls etc. The two conformist methods—Rise and Fall Method and Height of Point of Collimation (HPC) Method—each have strengths and limitations in accuracy, speed, and error detection. This paper proposes and assessed a merged computational approach that combines both methods in a single field book format to leverage arithmetic checks of both systems, reduce blunders, and improve reliability. Field tests shows a possibility that the merged method could reduce booking errors by a significant level and still maintains accuracy of ±0.008mm. The paper outlines procedures, mathematical formulation, advantages, limitations, and practical applications.