Which of the following equipment is NOT typically seen at the construction site of a traffic signal?

The grader is primarily used in the preliminary earth-moving phase of construction to create smooth, level surfaces, which is essential for roadwork and grading prior to any structural components, like traffic signals, being installed. However, when it comes to the specific installation of traffic signal equipment, it is not typically employed directly at the construction site.

In contrast, the aerial lift truck is essential for reaching overhead components such as traffic signal heads for installation and maintenance. The trencher is used extensively for digging trenches to lay the necessary wiring or cables for the traffic signal system. The horizontal boring machine is important for installing conduits under roads without having to dig all the way through, which minimizes disruption to existing infrastructure. Thus, while graders play a role in broader road construction projects, they are not directly utilized in the construction of traffic signals themselves.