Abstract: At 1:12 p.m. on March 15, 2017, Employee #1, employed by a welding company, and Coworker #1, the site superintendent for the general contractor, were working at a multiemployer residential construction project. Employee #1 was walking across the site's driveway. Coworker #1 was operating a Melroe/Ingersoll-Rand Bobcat skid steer-type haulage vehicle, with a Trojan Model P 60 concrete pump attached by chain to the skid steer's bucket. He was attempting to move the large concrete pump, which belonged to a concrete subcontractor, to the top of the steep driveway. At the top of the hill, the concrete pump began rolling backward, detached from the bucket, and rolled down the hill, striking Employee #1. Emergency services were called, and Employee #1 was transported to the hospital. He was admitted and treated for multiple serious injuries. Walking across the driveway at the residential construction site. Site superintendent for general contractor was attempting to move a large concrete pump to the top of the driveway using a Bobcat skid steer. At the top of the hill the concrete pump came loose and rolled down the hill striking an employee of one of the subcontractors. Fractures to both legs requiring surgery and hospitalization in excess of 24 hours. Struck-by accident.