IMSA Traffic Signal III case studies
IMSA Traffic Signal III · Put your knowledge to work in context.
The IMSA Traffic Signal Technician Level III credential is the senior tier of the International Municipal Signal Association's traffic signal certification ladder, aimed at technicians, crew leaders, inspectors, and engineers who already know how a signalized intersection is built and now need to defend the decisions behind it. Candidates are typically people who review signal plans, supervise installation and acceptance, configure controllers and detection, troubleshoot operations, and enforce standards and work zone safety on the street. The IMSA Traffic Signal III case studies are 5 cases and about 3,787 words.
1Plan Review: Clearance Intervals, Pedestrian Timing, and Detection on a 45 mph Arterial
You are reviewing the 60 percent signal design for a new intersection on a four-lane divided arterial posted at 45 mph (66 ft/s) at a two-lane minor street. Design inputs: stop line to the far edge of the conflicting through lane 60 ft; design vehicle 20 ft; perception-reaction 1.0 s; deceleration 10 ft/s²; level grade.
831 words, about 4 min2Acceptance of a Mast Arm Installation: Cure Time, Clearance, and Grounding
A contractor has installed a 45 ft galvanized mast arm pole with a 35 ft arm at a new signal. The footing is 3 ft diameter by 8 ft deep, designed for f'c = 3,000 psi at 28 days.
746 words, about 4 min3Minor-Street Green Times Out Every Cycle with No Traffic
A retimed eight-phase NEMA TS-2 intersection runs a 100 s coordinated cycle from 6 a.m. The arterial is phases 2/6 (two through lanes each direction, 1,500 vph); the minor street is phases 4/8 (one lane each direction, 90 vph combined).
768 words, about 4 min4Repeat Conflict Flashes After Rain at a Rural Intersection
A signal on a rural 55 mph arterial has flashed 12 times in eight weeks, always during or within a day of rain. The MMU event log shows seven POWER FAIL events (some only 0.2 s), three CONFLICT events (phase 2 green with phase 4 green, 130 ms), and two WATCHDOG events.
698 words, about 3 min5Temporary Signal Versus Flaggers for a Bridge-Widening Lane Closure
A bridge-widening project on a two-lane rural road (posted 45 mph, 1,800 vpd, 8 percent trucks) requires closing one lane for three months, 7 a.m. to 5 p.m., Monday through Friday.
744 words, about 4 min