Almost every vehicle carries a mobile phone, (not forgetting eCall) the whereabouts of which is known to the service provider. We can buy in that data to learn about traffic movements anywhere. No need for loops, CCTV, or manual counting.
At busy times there is a theoretical and demonstrable mathematical relation between speed and flow rate, which allows the construction of a Fourier representation of that flow into the future, enhanced by AI. More usefully it allows calculation of road capacity today, how near to maximum it is, and what it is likely to tomorrow.
A case study of M6 Jcn 19 shows how the technique is used to safely and easily validate junction design, but it also shows the power of the technique in making future predictions, and, when combined with weather forecasts, monitoring when fog actually exists on the road.
In summary, a powerful and easy way of understanding traffic patterns, and hence how to strategically plan to reduce and avoid congestion.