633.1 Loop geometry & tuning

Check placement, sensitivity, and frequency (344). Proper tuning stops HVM bollard false triggers.

Start with the installed loop drawing and the Induction Loops design criteria (344). Confirm slot position, size, number of turns, and tail routing match the approved detail; deviations change loop inductance and can mis-detect motorcycles or tall vehicles. Verify loop lead-ins are twisted and that joints are potted to maintain IP rating and reduce cross-talk.

At the detector, record base inductance, sensitivity step, and frequency channel. Use a loop simulator to prove stable “vehicle present” and “vehicle absent” states without chatter. Then field-prove with a car and a motorcycle surrogate to confirm detection of small masses.

To finalize geometry settings quickly, use the Loop Placement Helper (929) to check coil dimensions vs lane width and bollard head positions. Where lanes are bi-directional, separate entry/exit logic in the Interlock Matrix (352) to avoid ambiguous states.

633.2 Photo-eyes & beams

Align, test block/unblock, and fail states. Verified beams protect crash rated bollard lanes (343).

Mount/align each photo-eye per the Safety Circuits page (343). Check the receiver gain, alignment LEDs, and beam height relative to the bollard head and the typical bumper height. Confirm “beam broken” produces the correct safe inhibit and that “beam clear” restores authority after the latched inhibit is reset if required by the alarm philosophy (536).

Introduce test objects (box, pole, child-height surrogate) to challenge detection at edges, then check nuisance immunity: sunlight/flicker across the beam, dust accumulation on lenses, and puddle reflections. Where lanes curve, consider dual beams or offset geometry to maintain reliable coverage.

633.3 Edges/mats (if any)

Press, release, and confirm latching. Reliable edges prevent unsafe HVM bollard moves.

For safety edges and mats, confirm wiring (normally closed vs normally open), correct channel mapping, and that a press generates an immediate stop/inhibit. Verify release timing and whether the inhibit is latched until an operator acknowledges the fault, per the Safety & Interlocks requirements (350, 352).

Test across corners and seams where mats meet paving modules, and inspect strain relief and drip loops at entry points. Log each activation with timestamp and lane ID to support SAT traceability (638).

633.4 Call points & keys

Test access requests and permissions (524). Correct authorization keeps crash rated bollard logic coherent (342).

Exercise every call device—push-button, keypad, key switch, RFID reader—observing the HMI & Local Controls (524) indications and the state machine (526). Check the authorization hierarchy and ensure keys/codes do not bypass safety devices & measures.

Confirm Request→Authorize→Execute sequencing and that overrides (e.g., emergency services) set the correct latched messages and audit entries (536, 547).

633.5 Signal debounce/filtering

Tune filters to remove chatter. Filtering makes HVM bollard inputs trustworthy (536).

Inspect each input’s debounce and persistence timers at the PLC. Fast edges (noise) must be rejected, but legitimate short events (e.g., quick beam breaks) must pass—balance by device. Record the final milliseconds per channel in the I/O List (523) and tag it in the configuration baseline (537).

Trend input “change-of-state” counts during a short soak test to surface noisy channels. Where environment drives noise (e.g., long loop tails), improve cable routing and earthing before over-filtering.

633.6 False trigger checks

Heat/sun, dust, glare, and rain tests (337, 363). Environmental checks maintain crash rated bollard reliability.

Challenge sensors under sun-load, glare, and wind-blown dust (337, 363). For loops, test wet-pavement behavior; for beams, test headlight glare and rain streaks. Record any nuisance alarms and adjust beam gain, hooding, or loop sensitivity one step at a time, updating the change log (537).

Re-run representative lane maneuvers (slow roll, stop-start, straddling the loop) to ensure genuine events still pass through filters. Where persistent issues remain, consider relocating the device or adding a second sensing modality to achieve redundancy.

633.7 Environmental effects

Record limits where sensors degrade. Records guide HVM bollard maintenance (734).

Document operating bands for each device: temperature, humidity, IP/NEMA rating, and cleaning intervals. Note any derating points (e.g., fog reduces beam range) and include them in the Preventive Maintenance Plan (734). Where coastal exposure applies, schedule lens cleaning and check seals more frequently (363).

633.8 Test forms & evidence

Complete standard forms with photos (716). Evidence accelerates crash rated bollard approvals (938).

Use the Evidence Capture Standards (716) and Witness & Inspection Forms (918). Attach wide→detail photo sets with device IDs, lane IDs, and COS logs. Keep a per-lane snapshot PDF for SAT (638), and file originals per the Submission-Pack Guidance (938).

633.9 Acceptance criteria

Pass/fail thresholds per ITP (714). Clear criteria reduce HVM bollard disputes.

Define measurable outcomes before testing: minimum detect rate by vehicle class, maximum allowed nuisance trips per hour, recovery behavior after inhibit, and evidence needed for sign-off. Map each line of the Interlock Matrix (352) to a test step so matrix-row traceability exists. Store all records under the project’s document matrix and update the handover pack index (736, 736).

633 Loop & Sensor Proving — FAQ