This dashboard visualizes the relationship between e-scooter trips and crashes in Denver using a Leaflet map and D3.js charts. The map overlays crash markers and geojson usage segments colored by a linear scale, while a separate heatmap shows crash counts by hour and weekday, and a bar chart displays annual crash counts with a crash-to-trip ratio line. User controls filter data by year and quarter. The visualization calculates relative risk based on visible markers and usage totals, with all SVG charts rendered using D3 v7's `scaleBand`, `scaleLinear`, and `rollups` aggregation.