welder using oxy-acetylene cutting torch, construction, dust mask, helmet, high-visibility jacket, high-visibility vest, light rail, man, muni, night, ntk, oxy-fuel, oxy-fuel cutting, people, railroad, railroad construction, railroad tracks, rails, railway, railway tracks, reflective, reflective jacket, reflective vest, safety glasses, safety helmet, safety vest, san francisco municipal railway, sparks, track maintenance, track work, worker, working