「垂直樁面水準點」討論

On the Vertically Set Benchmark

「水準點」是一種常見的基本測量標，功能在於提供垂直維度高程差測量之用。所以，「水準點」通常安置時，樁面是水平的，樁面有一個弧度，能明確定義在垂直方向上的一個「位」，便於沒有疑義地置放水準尺。但是「水準點」亦有樁面安置為垂直者，亦即樁面平行於鉛錘線方向，稱為「垂直樁面水準點」。本文記載2023年6月探訪「舊金山潮位站」所見該站所屬水準點中之一個「垂直樁面水準點」，並彙整介紹「垂直樁面水準點」與其測量時使用之方式。

A leveling benchmark is a commonly used surveying monument that serves as a reference point for leveling surveys. The primary function of a benchmark is to provide support for accurate leveling measurements. Typically, the face of a benchmark is positioned horizontally, featuring a convex shape on top to define a unique level in the vertical dimension. This configuration allows for the placement of a leveling rod during surveying activities.
While horizontal placement is the norm for benchmarks, it is also possible to position them vertically. In this case, the face of the benchmark is aligned parallel to the plumb line, and it is referred to as a ''vertically set benchmark'' (vertical benchmark). This writing documents a vertical set benchmark encountered by the author during a visit to the San Francisco tide station in June 2023. The methods described can be applied to leveling surveys utilizing a vertical set benchmark.