5103, this is pretty dull stuff but the FHWA rule specifies "all workers" who are exposed to traffic, not just those repairing a road and does not carve out those subject to another federal agency. Rather than worry about whether a particular road adjacent to the tracks is a federal aid highway or not it is easier to simply have the vests for everyone whether flagging a crossing signal, getting into a crew van on the shoulder, etc. etc.

While not perfect, if you consider the thousands of new hires that have joined the workforce starting several years ago when Railroad Retirement was adjusted to apply to those reaching 60 years of age with 30 years service, safety hasn't been too bad.