This example shows a radial stacked bar chart that compares accident counts for the inner and outer lanes across 109 kilometer markers of the Moscow Ring Road. Each wedge’s length represents the combined total for both categories per kilometer, with the two stacked segments colored blue and green and a dashed red circle marking the mean accident value. The visualization is built with D3 v4, using `d3.stack()` to compute the stacked series and `d3.arc()` to generate the annular paths around a circular scale. Tick circles and labels are positioned via the linear radius scale, while kilometer labels are rotated along the outer edge.