NICET - Highway Construction Inspection Practice Exam

Which of the following describes the four different hair lines seen through a level?

1. Upper stadia, middle cross, lower stadia, and vertical cross

2. Vertical line, horizontal line, cross line, and diagonal line

3. Upper line, middle line, lower line, and reference line

4. Primary line, secondary line, mark line, and angle line

The correct answer is: Upper stadia, middle cross, lower stadia, and vertical cross

The four different hairlines seen through a level are referred to as the upper stadia, middle cross, lower stadia, and vertical cross. This terminology is fundamental in leveling instruments, particularly in surveying and construction tasks. The upper and lower stadia lines are used for measuring distances indirectly, based on the principle of stadia surveying, where the differences in the readings between these lines can indicate the distance from the instrument to the target. The middle cross line serves as a reference point for aligning the instrument and ensuring that measurements are taken accurately. The vertical cross line assists in precise vertical alignment and aids in determining vertical angles and heights. The other options do not accurately describe the specific features associated with leveling instruments. While they may include types of lines, they do not encompass the standard nomenclature used when discussing leveling hairlines in surveying contexts. Thus, the terminology provided in the correct choice is essential for anyone involved in highway construction inspection and surveying.