Add a layer with bus stops and frequency. #463

src/lib/browse/LayerControls.svelte

@@ -26,6 +26,7 @@
   import RoadSpeedsLayerControl from "./layers/lines/RoadSpeeds.svelte";
   import RoadWidthsLayerControl from "./layers/lines/RoadWidths.svelte";
   import TramsLayerControl from "./layers/lines/Trams.svelte";
+  import BusStopsLayerControl from "./layers/points/BusStops.svelte";
   import CriticalIssuesLayerControl from "./layers/points/CriticalIssues.svelte";
   import CrossingsLayerControl from "./layers/points/Crossings.svelte";
   import CycleParkingLayerControl from "./layers/points/CycleParking.svelte";
@@ -84,6 +85,7 @@
   <CollapsibleCard label="Public transit">
     <BusRoutesLayerControl />
     <TramsLayerControl />
+    <BusStopsLayerControl />
   </CollapsibleCard>
   <CollapsibleCard label="Boundaries">
     <CheckboxGroup small>

src/lib/browse/colors.ts

@@ -20,6 +20,7 @@ export const colors = {
   cycle_parking: "black",
   crossings: "green",
   trams: "black",
+  bus_stop: "black",
 
   // Thanks to https://github.com/cyipt/cyipt-website/issues/23
   cycle_paths: {

src/lib/browse/layers/points/BusStops.svelte

@@ -0,0 +1,92 @@
+<script lang="ts">
+  import {
+    ExternalLink,
+    HelpButton,
+    Popup,
+    publicResourceBaseUrl,
+  } from "lib/common";
+  import { Checkbox } from "lib/govuk";
+  import { layerId, makeColorRamp } from "lib/maplibre";
+  import { CircleLayer, VectorTileSource } from "svelte-maplibre";
+  import { colors } from "../../colors";
+  import OsOglLicense from "../OsOglLicense.svelte";
+  import SequentialLegend from "../SequentialLegend.svelte";
+
+  let name = "bus_stops";
+
+  let colorScale = colors.sequential_low_to_high;
+  let limits = [0, 3, 10, 20, 30, 100];
+
+  let show = false;
+</script>
+
+<Checkbox id={name} bind:checked={show}>
+  Bus stops
+  <span slot="right">
+    <HelpButton>
+      <p>
+        Data from the <ExternalLink href="https://data.bus-data.dft.gov.uk">
+          Bus Open Data Service
+        </ExternalLink>, as of 7 February 2024. To calculate frequency, every
+        scheduled arrival time per stop is considered, grouped by day of the
+        week. The total daily count is just the number of scheduled arrivals for
+        a day. The peak hour frequency is the highest number of buses in any one
+        hour window. That window might not lined up perfectly on the hour -- a
+        peak hour might occur from 8:25 to 9:25,for example.
+      </p>
+      <p>
+        There are known limitations with this layer, so please use caution when
+        using these numbers. Some stops may not be shown at all. Frequency could
+        be over- or under-counted, due to exceptions to the regular daily
+        schedule of a service.
+      </p>
+      <OsOglLicense />
+    </HelpButton>
+  </span>
+</Checkbox>
+{#if show}
+  <p>Peak hourly frequency:</p>
+  <SequentialLegend {colorScale} {limits} />
+{/if}
+
+<VectorTileSource
+  url={`pmtiles://${publicResourceBaseUrl()}/v1/${name}.pmtiles`}
+>
+  <CircleLayer
+    {...layerId(name)}
+    sourceLayer={name}
+    paint={{
+      "circle-color": makeColorRamp(["get", "peak"], limits, colorScale),
+      "circle-radius": [
+        "interpolate",
+        ["linear"],
+        ["zoom"],
+        1,
+        2,
+        8,
+        3,
+        13,
+        10,
+      ],
+    }}
+    layout={{
+      visibility: show ? "visible" : "none",
+    }}
+    manageHoverState
+    eventsIfTopMost
+  >
+    <Popup let:props>
+      <p>
+        Stop name: <b>{props.stop_name}</b>
+      </p>
+      <p>
+        Peak frequency: <b>{props.peak}</b>
+        buses per hour (for the busiest hour of any day)
+      </p>
+      <p>
+        Total buses per day: <b>{props.total}</b>
+        (for the busiest day of the week)
+      </p>
+    </Popup>
+  </CircleLayer>
+</VectorTileSource>

src/lib/maplibre/zorder.ts

@@ -94,6 +94,7 @@ const layerZorder = [
   "crossings",
   "vehicle_counts",
   "stats19",
+  "bus_stops",
 
   // Polygons are bigger than lines, which're bigger than points. When geometry
   // overlaps, put the smaller thing on top