A new project has shown that by using existing sources of information about traffic flow it is possible to create a minute-by-minute image of congestion in cities.
via Using real-time road traffic data to evaluate congestion – Research – University of Cambridge.
Research being done in the UK, with emphasis on data collection using low cost sensors. Seems fairly easy to deploy, but their system does use inductive loops in roads through, which have a high installation cost.
The researchers also collected real-time traffic light data using the Split Cycle Offset Optimization Technique and demonstrated how that data can be combined with bus data to give buses priority at traffic lights.