# Impact of Road Traffic Tendency in Europe on Fatigue Assessment of Bridges
## 2 Real Traffic Measurements
### Comparison of Traffic Data
* distributions of tandem axle loads are always bimodal: for Igualada traffic, the first mode is around 65 kN, the second mode, not particularly marked, is around 210 kN; for Moerdijk traffic, the two modes are around 45 kN and 100 kN, respectively; for Auxerre traffic, the first mode is around 110 kN, the second mode is around 180 kN;
* distributions of tandem axle loads of Igualada and Auxerre traffics are characterized by similar upper tails, well pronounced even beyond 250 kN; while that concerning the Moerdijk traffic is much less evident;
* except for Igualada traffic, distributions of tridem-axle loads are generally unimodal: the mode of Moerdijk traffic is around 150 kN; the mode of Auxerre traffic is around 330 kN;
* distribution of tridem-axle loads of Igualada traffic is tri-modal: the first mode is around 105 kN, the second and third mode around 170 kN and 210 kN, respectively;
* distributions of tridem-axle loads are characterized by clearly different upper tails: Auxerre traffic exhibits the most relevant one, followed by Moerdijk traffic and then by the Igualada traffic, characterized by the lowest;
* distributions of total weights for Igualada and Moerdijk traffic are bimodal: for Igualada traffic, the first mode is around 190 kN, the second mode, not particularly marked, is around 320 kN; for Moerdijk traffic, the first mode is again around 190 kN, the second mode is around 410 kN;
* distributions of total weights for Auxerre traffic is tri-modal: the first mode is around 30 kN, corresponding to light unloaded vehicles, the second mode, not particularly evident, is around 250 kN, the third mode is around 440 kN;
* distributions of total weights of Moerdijk and Auxerre traffics are characterized by similar upper tails, even if the one of Moerdijk is much more extended due to the presence of a small percentage of weighty LHVs, while that regarding Igualada is less pronounced; finally,
* distribution of _UDL_ is unimodal for Igualada traffic, with the mode around 12 kN/m; bimodal for Moerdijk traffic, with the first mode again around 12 kN/m and a second mode, marked weekly, around 28 kN/m; tri-modal for Auxerre traffic, with the first and the second mode, not particularly evident, around 12 kN/m and 32 kN/m, respectively, and the third mode around 45 kN/m;
* distributions of _UDL_ for Igualada and Moerdijk traffics are very similar, the upper tail being more pronounced in the case of Moerdijk traffic; on the opposite, the distribution of _UDL_ of Auxerre traffic is manifestly more heavy, with the upper tail extending well over 60 kN/m;
* total weight of lorry vehicles LHVs could attain very high value, but usually this level is associated with axle loads not beyond the legal limit;
* as clearly perceptible comparing _UDL_ distributions, Moerdijk traffic appears, in general, less demanding than Auxerre traffic, despite the fact that occasionally axle loads can be higher;
* excluding tandem-axle load distributions, which appear not dissimilar, Igualada traffic looks, in general, lighter than Auxerre traffic;
* apart from tandem-axle load distributions, Moerdijk traffic results, in general, moderately heavier than Igualada traffic. On the basis of these remarks, it seems confirmed that Auxerre traffic composition stands for a kind of upper limit for actual European traffic. Moreover, the fact that Auxerre data were probably systematically overestimated, since they were obtained by means of past-generation WIM devices less accurate than the updated ones available of today, contributes to further strengthening the conclusion. Consequently, although this aspect is out of the scope of the present paper, it seems that static load models of EN1991-2, based on Auxerre traffic, are able to represent not only Igualada but also Moerdijk traffic effects, thereby confirming, at this stage, its effectiveness. However, to draw more definitive conclusions deeper specific studies are still necessary.