Dynamite was essential to the rapid construction of the A&S along the Susquehanna River, where rock cliffs were blasted for months to create shelves for rails, with the older Port Road on a lower route and the new A&S on an upper route, both crossing the mouth of the Conestoga River at Safe Harbor on sweeping curves and new tandem bridges. Compressed air from a converted rolling mill in Safe Harbor was piped up the cliffs to drill pilot holes for explosives, boxed dynamite was passed by hand along the dangerous river face, and hundreds of holes were detonated at once before debris was removed and the process repeated. Dynamite was manufactured locally by local residents, unlike the PRR construction crews, which included thousands of transient immigrant laborers. On June 9, 1906, a dynamite factory explosion near Colemanville, a few weeks before the public dedication of the A&S, killed eleven people, eight of them between the ages of 16 and 25. The bodies were so badly destroyed that mostly unidentified fragments were collected, funeral services were held at the Colemanville United Methodist Church, and a single casket was buried for the remains of ten victims. Although the factory was no longer producing dynamite for the A&S, the PRR remained associated with what the Lancaster New Era called "the most horrible accident that ever occurred in Lancaster County."