###### Abstract  
_Applied Sciences_ has achieved a major milestone this year: it is the 10 th anniversary of the journal. To celebrate the occasion, this Special Issue of the Civil Engineering section is being published, featuring leading authors in Civil Engineering. It features advances in diverse areas of this field, reflecting the breadth of Civil Engineering. Authors who are well-known experts in their fields of study have published contributions in Structures, Geotechnics, Transportation and in the cross-cutting topic of Optimization. There are a number of papers on Structural issues, with applications to both bridges and buildings. [PERSON] and [PERSON] [1] consider an analysis issue for box girder bridges. Highly sophisticated analysis models are widely available but their use sometimes distracts the user from the underlying bridge behavior--its response to load. It is very welcome to have a paper addressing such a fundamental analysis issue as the nature of the torsional/ distortional behavior of this bridge form. As box girders become larger and more slender, distortion is likely to become more significant and it is good to have simple models that can provide designers with insights into its significance. [PERSON] et al. [2] also make a contribution to the Bridge Engineering literature, this time on the issue of fatigue. Hot-spot stresses are a particular analytical challenge and are a design issue for orthotropic bridge decks. [PERSON] et al. present a guideline for the calculation of these stresses, which can be used to better evaluate the fatigue life of these all-important details. They suggest that shell elements produce more consistent hot-spot stress results than solid elements for stress at two important locations: at the rib toe and the highly non-linear deck toe. The contribution of [PERSON] et al. [3] also relates to bridges but is on the subject of health monitoring, as opposed to design. One of the greatest challenges in bridge health monitoring is the variability of the applied traffic load. It is difficult to interpret data when they include the responses to vehicles with very different weights and numbers of axles. [PERSON] et al. address the challenges of axle detection--finding the number of vehicle axles, where they are on the bridge and tracking their locations during the vehicle crossing event. The technique has the potential to greatly enhance bridge health monitoring by allowing measured responses to be broken down into equivalent single-axle responses, thereby facilitating the integration of data from a variety of different vehicles. Buildings are the subject of two Structures papers. [PERSON] et al. [4] review recent trends in tall building design towards diagrid structures. Simplified methodologies for preliminary analysis and design are reported, as well as the issue of using the pattern to optimize the structural response. Complicating issues are also addressed, including local deformability, stability and shear-lag. This seems to be an active area of development, with mention of twisted, tapered, tilted and freeform diagridt towers and hexagrids. [PERSON] et al. [5] consider the responses of much smaller, timber blockhaus structures to earthquake loading. With increasing emphasis being placed on renewable materials, timber seems likely to be the focus of increasing interest in construction. Blockhaus structures have particular potential but there are also challenges due to their intrinsic geometrical and mechanical features, such as stacking of logs and door/window openings. [PERSON] et al. propose a simplified method of analysis to assess their resistance to earthquake loading and validate the results through comparison with more sophisticated finite element analyses. Three papers relate to transportation infrastructure. [PERSON] et al. [6] investigate the environmental implications of a high-speed railway tunnel in China. They find that the materials used during construction account for over 97% of the CO\({}_{2}\) emissions of the life-cycle.