The retired counter tracked vehicle detections across three calibrated lines, stored events on the camera machine and published aggregate time buckets. This describes the archived records only.
01
Sample
A 960 × 540 computer-vision frame was read at about one frame per second from the same fixed camera that supplies the live stream.
02
Detect
In daylight, YOLOv8n looked for cars, motorcycles, buses and trucks in enlarged crops covering 106th Avenue, the west driveway and the east service road.
03
Track and cross
A centroid tracker associated detections between frames. A count was written only when a track crossed one of three calibrated line segments in a defined direction.
04
Switch after dark
Below a scene-brightness threshold, the system changed from vehicle-shape detection to moving bright-blob detection and attempted to merge a pair of headlights into one vehicle track.
05
Aggregate
Crossing events remain in local SQLite; roughly every three minutes the former metrics service published aggregate totals, a trailing 60-minute count and Pacific-time hourly buckets. The metrics request contained counts, not vehicle images or identifiers.
Data dictionary
What each number counts.
Every total is a detected line-crossing event—not a unique-vehicle or occupancy count.
Definitions for the public construction-activity fields
Field
Display name
Definition
Unit
entry
Entering
A tracked crossing into the site through either the west driveway or the east service-road access.
crossing event
exit
Leaving
A tracked crossing out of the site through either counted access. It is not a count of people or occupied vehicles.
crossing event
street
Street traffic
A tracked passage across the calibrated 106th Avenue line. Hourly downloads combine both travel directions.
vehicle pass
streetUp / streetDown
Directional street split
Movement up or down the camera frame in the former latest-snapshot payload. These image-relative directions are not exported as cardinal compass directions.
vehicle pass
lastHour
Last hour
A rolling 60-minute window ending at the latest camera-side aggregation, not the previous completed clock hour.
crossing event
busiestHour
Busiest hour
The Pacific civil-clock hour with the largest sum of street, entry and exit events so far that day.
hour 0–23
Time semantics & gaps
Missing is not zero.
The former counter used rolling totals and clock-hour buckets. Only the stored historical buckets remain available here.
Clock and freshness
Dates and hours use America/Los_Angeles local civil time. The ISO timestamp for the latest update remains UTC.
The final day and clock-hour may be partial. Counting has ended; missing later records are not observations of zero traffic.
At the autumn daylight-saving transition, both occurrences of the repeated local hour are combined into the same 0–23 bucket. The skipped spring hour has no observations.
The public CSV and JSON are cached historical exports. Their generation time is the download time, not a new observation.
Coverage and zero
Only hourly buckets containing at least one entry, exit or street crossing are persisted to the public hourly table. An absent row therefore does not mean a verified zero.
Missing days must be treated as gaps, never measured zeros. Days with recorded buckets can still have incomplete coverage; the archive does not certify continuous observation.
A weekday-by-hour average derived from these sparse records is a mean of observed buckets rather than an unbiased typical-day estimate. Missing buckets must not be filled with measured zeros.
A numeric zero inside an exported row means no crossing of that type was recorded during a bucket that exists because another type was counted; it still is not proof that detection coverage was complete for the whole hour.
Detector history
The series changed as the counter was calibrated.
Configuration history checked September 7, 2026. These revisions are part of the evidence: an apparent change in the historical series can reflect a detector change as well as a change on the street or site.
Initial merged baseline
The first repository version used YOLOv8n with ByteTrack on the full camera frame, with one lot-entrance line and one 106th Avenue line.
Comparability: This narrow, full-frame configuration is not method-equivalent to the later cropped, three-gate detector.
A brightness switch added moving bright-blob detection after dark, attempted to merge paired headlights, and separated street movement by image direction.
Comparability: Day and night observations use different detectors; the night series is a rougher estimate and should not be treated as interchangeable precision.
Daylight detection moved to an enlarged road crop and a centroid tracker because small, fast vehicles were being missed or losing track identity at the one-frame-per-second sample rate.
Comparability: This is a material method break: counts before and after the change should not be read as a clean trend without acknowledging the detector revision.
The detector added separate west-driveway, east-service-road and 106th Avenue line segments, with two daylight crops and common entry/exit aggregation across both site accesses.
Comparability: Gate coordinates and crop calibration are tied to the present fixed view. A camera move, zoom or reframing would create another method break and require recalibration.
A vehicle that leaves and returns can be counted more than once. The aggregates cannot measure unique vehicles, occupancy, dwell time, people or material quantities.
02
One oblique view
Trees, fencing, parked equipment, other vehicles and the edges of the two detection crops can hide or partially obscure a crossing.
03
Low sampling rate
At about one frame per second, small or fast vehicles can move a long distance between samples. Tracks can be lost, joined to the wrong detection or split into more than one track.
04
Night is a different detector
Rain, reflections, work lights, headlight glare and closely spaced vehicles can merge, split or hide bright blobs. Night counts are materially rougher than daylight counts.
05
Calibration can drift
The three crossing lines are pixel coordinates tied to this exact crop and angle. Any camera movement, zoom or framing change requires recalibration before the series is comparable again.
06
Not an official survey
The counter is an independent observational estimate. It is not Bellevue traffic-count data and should not be used alone for safety, permitting or engineering decisions.
Open data
Download the sparse hourly record.
Each file contains the stored non-zero hourly buckets from when the pipeline was operating. Neither format supplies a complete hourly coverage grid, so retain the missing-data caveat when analysing it.