Standards, Codes, and Work Zone Safety
Which document governs, and who is protected
This domain rewards candidates who know which standard controls a given situation and can compute temporary traffic control geometry.
The MUTCD is the national standard for signs, markings, signals, and temporary traffic control; state and local manuals may be more restrictive but may not be less. The AASHTO Green Book covers geometric design. The NEC (NFPA 70) governs service and cabinet wiring, while the NESC governs supply and communication lines, including span work. NFPA 70E addresses electrical safe work practices and arc flash; OSHA 1926 applies to construction safety, including Subpart P excavation and trenching requirements and lockout/tagout. ADA and PROWAG drive pedestrian accessibility, including detectable warnings and push-button reach ranges.
For work zones, know the parts of a temporary traffic control zone: advance warning area, transition area, activity area (including the work space, traffic space, and buffer space), and termination area. Worker protection means high-visibility apparel to the appropriate ANSI/ISEA 107 class, proper signage, and positive protection where warranted.
Worked example - merging taper length: for 40 mph or less, L = W × S² / 60; above 40 mph, L = W × S. Closing one 12-ft lane on a 45 mph road: L = 12 × 45 = 540 ft. On a 30 mph road: L = 12 × 900 / 60 = 180 ft. Note how speed dominates the result.
Traps: quoting an OSHA rule where the MUTCD applies; forgetting that a state standard can be stricter than the MUTCD but never looser; using the low-speed taper formula above 40 mph.