Bob: The watchmen date back to the PRR era. When the PC came along, the watchmen were eliminated, in favor of bulletin order s describing work zones and proceedures for passing them, mostly as George described earlier in this thread. After Amtrak took over, and a few fatal accidents occurred, Amtrak revived the Watchmen along with other new methods of protection. They are not the only layer of protection, but are effective, especially along curves. Usually, the foreman in charge owns the out of service track, and gets fouling time authority to obstruct adjacent tracks, for a specific time, after which he must report clear.
I brought up the absence of the Watchmen because they are another set of eyes that are focused on oncoming trains. Working on or about tracks on the NEC is significantly more dangerous because of the high speeds involved, along with the nature of the quieter equipment. It should be noted, that each workday, numerous track maintenance employees perform their duties in a safe and efficient manner. This accident was a preventable, and likely caused by bad judgement on the part of individuals who knew better. If true, a sad situation indeed.