Equal green time for two crossing directions can be a poor choice when one direction carries much more traffic. The under-served approach accumulates a queue while the quieter approach receives green time it cannot fully use.
Side-by-side versions of the same crossroads face substantial demand, with the horizontal movement roughly twice the vertical one. One uses equal signal splits; the other adjusts the green allocation using Webster's timing logic while retaining the same yellow intervals. Dynamic queue totals on the right make the consequences visible over many cycles. The point is not that a single timing formula is perfect in every circumstance. It is that signal timing should reflect competing demand and lost time rather than divide a cycle mechanically. A well-chosen split can keep queues from growing needlessly without changing the intersection's physical layout.
Four green lights along a corridor do not guarantee a smooth trip. If their timing is unrelated to travel between intersections, a vehicle released by one signal may arrive at the next just as it turns red. The same road can therefore produce repeated stops without any change in demand or geometry.
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An intersection contains several traffic streams that would like to move at the same time. The problem of signal phase design is to allow compatible streams together while separating movements whose paths cross. The video turns that spatial safety rule into a graph problem.
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The center of a conventional intersection forces many turning paths to compete for the same space. A knotted intersection rearranges those paths and schedules passage through several smaller conflict areas, allowing movements to weave through a compact geometry in a controlled rhythm.
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