In July 2011, a 46 year-old male equipment operator (victim) working for a trenchless utility installation contractor suffered fatal crushing injuries when a horizontal auger boring (HAB) machine overturned. At the time of the incident, the victim was installing three steel pipe casings using a trenchless method called pipe ramming at a municipal water project site. Each casing was 36 in (0.9 m) in diameter and 40 ft. (12 m) long. The casings were driven horizontally through the ground by a pneumatic ramming hammer. On the day of the incident, the victim was operating an HAB machine to bore inside the casings to remove earth material that filled the casings during installation. The machine was mounted on a track assembly and the track assembly was not anchored to the ground. The weight of the machine and the track assembly was 15,800 lbs. (7,167 kg). The victim was operating the machine at the operator's platform located on the left side of the machine (when facing the casing). The incident occurred shortly after 10:00 am when the auger string had advanced approximately 11 ft. (3.4 m) into the casing. The HAB machine along with the track assembly suddenly pitched to the left roughly 90 degrees counterclockwise. Unable to jump free, the victim was pinned by the machine against the ground before the machine swung back to the upright position. Immediately the machine pitched to the left a second time, crushing the victim, and swung back upright before it pitched the third time and rested on its left side with the motor running and the victim pinned underneath. A coworker immediately called 911. Meanwhile an equipment operator at the site used an excavator to move the machine off the victim. The workers were able to turn the machine off and free the victim. They performed CPR on the victim until the EMS arrived. The victim died on route to the hospital as a result of severe crushing injuries. Contributing Factors: 1) Auger boring was conducted without having a casing securely attached to the machine's master casing pusher: a bare auger string bored inside a preinstalled casing. 2) Measures to stabilize the boring machine and prevent machine upset were not implemented. Key Recommendations: 1) Employers should ensure that operators always bore with the casing securely attached to the HAB machine as required by the manufacturers and implement additional measures to stabilize the boring machine when necessary. 2) Employers should provide employee training on precautions and measures for preventing boring machine upset. 3) Utility installation project designers, engineers and managers should incorporate measures to prevent boring machine upset at the project design stage. 4) Boring machine manufacturers should consider the following measures to prevent machine overturn: a) Widen the base of the HAB machine with outriggers to increase stability

b) Provide a remote control device for operating HAB machines

c) Move the operator platform to the rear end of the machine

d) Install rollover protection bars or a cage to protect the operator

e) Install a torque meter or a RPM limiter and an interlock to shut down the machine when the output torque and RPM exceeds the safe limits

f) Install a pressure meter on the machine base to monitor stability and an interlock to shut down the machine before it overturns

g) Modify the machine base and track assembly design so that the machine can be anchored into the ground

and h) Warn operators about the danger of boring inside a preinstalled casing without stabilizing the machine.