Fig. 2

Panels (a)–(d) show the first four left singular vectors \(\hat {\mathbf {u}}_{1| q},\dots \hat {\mathbf {u}}_{4|q}\) of the estimated 96 × 8 daily variation matrices \(\hat {\boldsymbol {\Gamma }}_{q}\) for three cities q ∈ {Vienna, Linz, Lyon}. Panels (e)–(h) show the corresponding loading vectors \(\hat {\sigma }_{1|q}\hat {\mathbf {v}}_{1| q},\dots , \hat {\sigma }_{4| q}\hat {\mathbf {v}}_{4| q}\) calculated by multiplication of the respective singular value \(\hat {\sigma }_{i| q}\) and right singular vector \(\hat {\mathbf {v}}_{i| q}\). Roads of type (frc) 2 are excluded from the estimation due to lack of corresponding data. The zero loadings for road type 2 in panels (e)–(h) reflect this omission