Measuring congestion at road-diet reductions using probe vehicle data

Road diets provide a means to reduce traffic speeds and promote alternative travel modes within the United States. Throughout the state of New Jersey there are approximately 50 existing road diets with more planned. While research has shown that road diets improve safety, no defined means to measure their long-term impact on traffic flow were found. This paper explores some new and existing means for applying intelligent transportation techniques to quantify long-term congestion changes through commercial anonymous probe vehicle (APV) speed data, the annual average daily traffic and other factors. Two case studies are used to evaluate congestion performance metrics, analysing 8 million APV speed records. Although there are a number of variables to consider, this preliminary research establishes a base measure for evaluating the pre- and post-road-diet impact on traffic flow.