Unsupervised machine learning to analyse city logistics through Twitter

City Logistics is characterized by multiple stakeholders that often have different views of such a complex system. From a public policy perspective, identifying stakeholders, issues and trends is a daunting challenge, only partially addressed by traditional observation systems. Nowadays, social media is one of the biggest channels of public expression and is often used to communicate opinions and content related to City Logistics. The idea of this research is that analysing social media content could help in understanding the public perception of City logistics. This paper offers a methodology for collecting content from Twitter and implementing Machine Learning techniques (Unsupervised Learning and Natural Language Processing), to perform content and sentiment analysis. The proposed methodology is applied to more than 110 000 tweets containing City Logistics key-terms. Results allowed the building of an Interest Map of concepts and a Sentiment Analysis to determine if City Logistics entries are positive, negative or neutral.

Modelling the Time-dependent VRP through Open Data

This paper presents an open data approach to model and solve the vehicle routing problem with time-dependent travel times (TDVRP). The proposed model is based on a multi-layer matrix composed of travel times, replacing the traditional distance matrix. Online cartography services are queried in order to build this matrix. Travel times are obtained for every step in the time discretization. Thus, the model integrates the fact that the travel time between two points is modified during the time horizon. This model is applied to a medium-sized problem in the urban area of Paris using an enhanced Greedy Randomized Adaptive Search Procedure (GRASP). This work intends to build on the current state of the art by proposing a straightforward and open-access method to model and solve the VRP with traffic variability.