Figure 1.
Maps of geo-located tweets, roads and railways.
(a) Geo-located tweets on a map. (b) Highway network. (c) Railway network.
Figure 2.
Histograms of total lengths by country of highways and railways.
(a) Highways total length by European countries. (b) Railways total length by European countries. (c) Ratio between the total length of highways and that of railways by several European countries. The red line marks the unit ratio.
Figure 3.
Twitter penetration rate across Europe.
(a) and (c) Geolocated Twitter penetration rate across Europe at country level (a) and NUTS 2 level (c). Twitter penetration rate is defined as the ratio between the number of users emitting geo-located tweets in our database and the population in 2012. (b) and (d) Penetration rate as a function of the Gross Domestic Product (GDP) per capita at country level (b) and NUTS 2 level (d). At country level, the figures for the GDP were obtained from the web of the International Monetary Fund [30], correspond to the year 2012 and are expressed in US dollars. At NUTS 2 level, the figures for the GDP were obtained from the web of Eurostat [32], the figures for GDP correspond to the year 2011 and are expressed in euros. Each point represents a country or a NUTS, the red points in (d) represent the NUTS 2 of Turkey.
Figure 4.
Distribution of the social network's degree.
(a) Probability distribution of number of ties of an individual in the social network of 5 countries drawn at random among the 39 case studies. (b) Box plot of the 39 fitted exponent values. (c) Box plot of the R2 values. The box plot is composed of the minimum value, the lower hinge, the median, the upper hinge and the maximum value.
Figure 5.
Highway and railway coverages.
(a)–(b) Locations of the geo-located tweets on the road (a) and rail (b). (c)–(d) Segments of road (c) and rail (d) covered by the tweets. The red segments represent the segments covered by the tweets.
Figure 6.
Top 20 of the countries ranked by highway coverage (a) and railway coverage (b).
Figure 7.
Highway and railway coverages as a function of the penetration rate.
(a) Highway coverage as a function of the penetration rate. (b) Railway coverage as a function of the penetration rate. (c) Railway coverage as a function of the highway coverage. Red lines are linear regression curves applied to the log-log plots. This mean that the slope corresponds to the exponents of power-law relationships. The slope in (a) is around 0.6, 0.8 in (b) and 1 (a linear relation) in (c).
Figure 8.
Proportion of tweets in transports.
(a) Proportion of tweets on the highway or railway networks by European countries. (b) Proportion of tweets according to the transport network by European countries. The blue color represents the tweets on the road. The red color represents the tweets on the rail. The proportions have been normalized in order to obtain a total proportion of tweets in transport equal to 1.
Figure 9.
Box plots of the distribution of rail passenger-kilometers expressed in percentage of total inland passenger-kilometers according to the proportion of tweets on the rail among the tweets on the road and rail.
The red color for countries having a proportion of tweets on the rail less than 0.5. The blue color for countries having a proportion of tweets on the rail higher than 0.5.
Table 1.
Difference between the percentage of rail passenger-kilometers and difference between the railway coverages for each pair of countries having a highway coverage higher than 20% and an absolute different between their highway coverages lower than 5%.
Figure 10.
Comparison between the Average Annual Daily Traffic and the number of tweets on the road.
(a)–(c) Comparison between the Average Annual Daily Traffic and the number of tweets on the highways in France (a) and United Kingdom (b). Points are scatter plots for each highway segments. (b)–(d) Box plots of the highway segment length according to the type of segment in France (b) and United Kingdom (d). The red color for the points above the black line and the blue color for the points below the black line.