Answer: The HDD process utilizes a range of specialized equipment designed for accuracy and efficiency. The primary tool is the HDD drill rig, which provides the power and control for the drilling operation. This is complemented by various drill heads and reamers designed for different soil conditions, from soft clay to hard rock. Other essential components include a drilling fluid mixing system to create and pump a fluid (usually a mixture of water and bentonite) to lubricate the drill bit and stabilize the bore path, as well as a locating system to track the drill head's position and ensure the correct path is maintained.