Researchers at the Institute for Cross Disciplinary Physics and Complex Systems in Spain conducted research on geo-located tweets in mapping patterns of transport use in roads and rails. Analysis of 5,219,539 tweets from 1,477,263 Twitter users in 39 European countries between September 2012 and November 2013 indicated that coverages vary from country to country and this might be due to different levels of Twitter infiltration in different countries. Variability might also be explained by differences in cultural factors related to mobility habits and online social interaction. Analysis also showed a positive correlation between Average Annual Daily Traffic on highways and the number of on-the-road tweets in the UK and France.