snowhfx

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A better Halifax sidewalk and cycling snow clearing map.

How it works

Every hour, a system of mine runs:

scraperlite -db snow.db https://www.halifax.ca/transportation/winter-operations/service-updates \
  clearingOps.html '#tablefield-wrapper-paragraph-125991-field_table-0' \
  updateTime.txt '#tablefield-paragraph-125991-field_table-0 > thead > tr > th.row_0.col_1.c-table__cell' \
  serviceUpdate.txt '#tablefield-paragraph-125991-field_table-0 > tbody > tr:nth-child(2) > td.row_1.col_1.c-table__cell' \
  endTime.txt '#tablefield-paragraph-125991-field_table-0 > tbody > tr:nth-child(3) > td.row_2.col_1.c-table__cell'

This uses scraperlite to scrape key parts of the Halifax Winter Operations Service Updates page, such as weather event end times.

The output of that is visible here, in the observations and contents tables.

cmd/features downloads the Active Travelways, Bike Infrastructure and Suggested Routes, and Ice Routes datasets and builds features.bin and features_cycling.bin.
features.bin encodes travelways:

• lines for each travelway (sidewalk, path, etc)
• their titles
• their snow clearing priority (1/2/3)

features_cycling.bin encodes cycling routes. Protected bike routes inherit priorities by matching against nearby travelways; other routes match ice routes first. If a match can't be found, WINT_LOS is used as a fallback. Routes marked as not plowed (or that match a nearby no-plow travelway) are skipped. Both files include a source dataset id to support popups.

cmd/events is run after scraperlite against the same database to produce the events table, visible here.
It scans through all observed changes and builds a log of notable changes to the service update and weather event end times.
From those it derives states.

cmd/api runs an API server against that same database and serves event data plus community condition reports:

• GET /api/v1/current-event
• GET /api/v1/community-reports?dataset_mode=...
• POST /api/v1/community-reports

Reports auto-expire after 3 days, and all active reports are expired when a new weather event id is observed.

index.html loads features.bin and features_cycling.bin for lines to show on the map (sidewalk and cycling modes) and queries this condensed events data for the current weather event state and last weather event end time.

The site runs on GitHub Pages.