IMSA Signal Inspector key terms

A separate monitoring device in the signal cabinet that watches controller outputs and forces the signal into flashing operation when it detects an unsafe condition such as conflicting green indications or a failed field output.

The current-generation term for the cabinet device that supervises signal outputs against programmed safety rules and places the intersection into a safe flashing state when a fault is detected.

The microprocessor-based device in the cabinet that runs the timing plan, reads detector inputs, and commands the signal displays through the output interface.

The set of load switches and relays that convert low-voltage controller commands into the higher-current signals that drive vehicle and pedestrian heads in the field.

A solid-state or relay device that switches line power to a specific signal indication, such as the green or red lamp of a given approach.

The cabinet terminal block where field signal conductors are landed and where technicians measure voltage and current for each indication during inspection and troubleshooting.

A timing circuit that detects when the controller stops executing its program normally and triggers a transfer to flashing operation or another safe fallback state.

A fail-safe operating condition in which the signal displays a flashing red or yellow indication on all approaches, typically entered when the monitor detects a fault.

The programmed set of intervals, splits, offsets, and phase sequences that the controller uses to operate the intersection during a given time of day.

A traffic movement or combination of compatible movements that receives right-of-way together as a single controlled unit within the signal cycle.

The time difference, measured from a system reference point, at which a local controller begins its cycle relative to adjacent coordinated signals.

The practice of timing adjacent signals so vehicles traveling at a design speed encounter progressive greens along a corridor.

The cabinet and controller connection through which a field sensor reports the presence or passage of a vehicle or pedestrian call.

A wire loop embedded in or saw-cut into pavement that senses vehicles through changes in inductance and reports calls to the controller.

The twisted pair of conductors that carries the loop signal from the pavement loop to the detector card in the cabinet, typically run in conduit with splices kept out of the roadway.

The physical area of roadway over which a detector reliably senses a vehicle, used to check whether stop-bar or advance detection is placed correctly.

A plug-in module in the cabinet that energizes a loop or processes sensor signals and provides presence or pulse outputs to the controller.

The housing assembly containing one or more signal lenses and visors that displays indications to a specific traffic movement.

The colored, optically shaped glass or plastic element that produces the red, yellow, or green indication when its lamp is energized.

A signal display unit using light-emitting diodes instead of an incandescent lamp, with different electrical load and monitoring characteristics that affect cabinet wiring and conflict monitoring.

The hood projecting from a signal head around each lens that reduces sun phantom and improves visibility of the indication in bright conditions.

The large contrasting panel mounted behind a signal head that increases the visibility of the signal against complex backgrounds.

The assignment of movements to phases and the order in which those phases are served, shown on a phasing diagram used for inspection and timing review.

On-site checking that installed signal equipment matches the approved plans and operates as designed, including display, detection, and cabinet functions.

A construction drawing updated to show the actual installed locations, quantities, and routing of signal equipment after construction is complete.

A written list of deficient or incomplete work items identified during inspection that the contractor must correct before final acceptance.

The project stage at which the work is sufficiently complete for its intended use, allowing the owner to accept the signal for operation while minor items remain.

The formal owner action closing out a signal project after all punch list items, testing, and documentation requirements have been satisfied.

The drawing and written plan showing how traffic, pedestrians, and workers will be protected through a work zone, including signs, channelization, and flagging.

The portion of roadway affected by construction or maintenance where normal traffic patterns are altered, divided into advance warning, transition, activity, and termination areas.

A section of work zone channelization where cones, drums, or barricades gradually shift traffic laterally around a closure.

A cone, drum, barricade, or tubular marker used to guide traffic along the intended path through or around a work zone.

A work zone control method in which a trained flagger stops and releases traffic using a stop/slow paddle to protect a one-lane operation.

The archived set of drawings and documents retained by the agency that reflects final installed conditions and supports future maintenance and inspection.

The conductors and connections between the cabinet and field devices, including signal heads, detectors, and pedestrian push buttons, that must be verified for continuity and correct termination.

A field device that registers a pedestrian call at the controller and must be inspected for reach, labeling, and reliable actuation.