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Enhancing safety whilst saving energy in tunnels due to an optimised choice of road surface materials The durability and longevity of concrete pavements is well known everywhere. Due to these characteristics the overhaul and maintenance requirements, provided the major construction and production principles are respected, are sharply reduced. This results in a prevention of transport disruptions respectively traffic jams and their subsequent costs. However, there are many more positive characteristics of concrete, which become more and more effective during the entire operating life of concrete surfaces, which are widely unknown. Among other things, concrete pavements can reduce the fuel consumption of lorries (resulting in a reduction of CO2 emission), due to non‐deformable pavements. Furthermore hardened concrete is able to absorb and store CO2 and there are advantages caused by the bright surface of the material. The Smart Minerals GmbH examines the aspect of brightness of concrete for the road surface of tunnels in the course of a research project. Due to the good photometric characteristics of concrete and the resulting higher brightness of the pavement, the road users have a subjective higher sense of safety and the bright surface of concrete causes a reduction of energy‐consumption for lighting. To ensure the required brightness of the pavement, concrete surfaces need much less powerful light sources. Therefore it is theoretically possible to reduce the power of the light source, compared to the asphalt surface, to an extent of two thirds. [ABSTRACT FROM AUTHOR]

Reduction of Urban Heat Islands with Whitetopping. The requirements for traffic areas in the urban zone are manifold and continuously increasing. The reduction of the heat islands, which adversely affect the urban climate due to their increased temperature, is of importance for the residents. An investigation revealed that light-coloured traffic areas can significantly reduce the surface temperature and overall temperature levels in urban areas (illustrated by the example of Vienna) and improve the visibility of traffic participants at unchanged illumination levels at night. As a rehabilitation measure the Whitetopping method is simple and cost-efficient for improving the load bearing capacity and brightness characteristics of urban traffic zones. Replacing asphalt roads with roads with a concrete topping, such as Whitetopping, with an albedo of 0.5 would lead to a daily air temperature reduction of approximately 1 °C in summer. The model simulations of the air temperature over a 150 m × 150 m homogeneous area with Whitetopping also show a decrease in temperature by 1 °C compared to asphalt. Since roads are representing 10 % of the total area of a city, efficient and long- term measures to improve the micro-climate and facilitate a further increase in traffic safety can be taken. [ABSTRACT FROM AUTHOR]

Ever more stringent requirements have been specified in recent years for the surfaces of tunnel inner linings with regard to surface porosity (with influence on the ease of cleaning) and lightness. These requirements are normally fulfilled by filling and applying tunnel paint. Recently there have been many cases of damage to paint or coating systems, sometimes only a few weeks after opening for traffic. This often includes the separation of the coating. This flaking leads to increased dirt adhesion and thus to a reduction of lightness and irritation to the field of view of the drivers. The refurbishment work, which is often necessary, leads to traffic obstruction like hold-ups and diversions. For this reason, the durability of the surface is of great significance, and innovative solutions are also being investigated in the field of concrete technology. The following article presents an alternative and durable method of fulfilling all the requirements placed on the surface of the tunnel inner lining. In den vergangenen Jahren wurden immer höhere Anforderungen an die Oberflächen von Tunnelinnenschalen betreffend Oberflächenporosität (Einfluss auf Reinigungsfähigkeit) und Helligkeit gestellt. Zur Erfüllung dieser Anforderungen werden meist Tunnelanstriche nach vorheriger Spachtelung verwendet. In letzter Zeit traten jedoch vermehrt Schäden an Anstrichsystemen auf, teilweise schon wenige Wochen nach Verkehrsfreigabe. Hierbei kommt es oftmals zu einem Ablösen der Anstrichschicht. Diese Ablöseerscheinungen führen aufgrund einer verstärkten Schmutzablagerung zu einer Reduktion der Helligkeit und zu Irritationen des Blickfelds der Verkehrsteilnehmer. Die oftmals erforderlichen Instandsetzungsarbeiten am Beschichtungssystem führen zu Verkehrsbehinderungen wie Staus und Umleitungen. Aus diesen Gründen ist die Beständigkeit der Oberfläche von großer Bedeutung, und innovative Lösungswege werden auch im Bereich der Betontechnologie erprobt. Im nachstehenden Beitrag wird eine alternative dauerhafte Methode vorgestellt, die alle Anforderungen an die Oberfläche der Tunnelinnenschale erfüllt. [ABSTRACT FROM AUTHOR]

Effects of traffic‐induced vibrations on young concrete: part 1 In the COUNT (Concreting under traffic) research project, the effects of traffic vibrations on young concrete are extensively examined. This research question has recently become more relevant since traffic closures often have to be imposed when bridges are renovated or widened, as there is a concern that the vibrations caused by traffic will damage the young (hardening) concrete. COUNT aims to determine critical vibration values and underlying damage mechanisms based on three test series. Both harmonic and real bridge vibrations due to train, truck and car traffic are adopted, and the effects on the material concrete itself are investigated, as well as on the bond behaviour between concrete and reinforcement, and the contact between existing and new concrete parts. This first part of the article reports on the results of test series 1 and 2, in which small samples were systematically excited by artificial vibrations during hardening. It was found that conventional traffic vibrations do not affect the strength of concrete per se, but that the bond between the concrete and the reinforcement can be weakened if the vibrations are too great. In addition, it was found that (differential) displacements is a more suitable measure for damage assessment than the vibration velocity. [ABSTRACT FROM AUTHOR]

While capabilities in urban climate modeling have substantially increased in recent decades, the interdependency of changes in environmental surface properties and human (dis)comfort have only recently received attention. The open-source solar long-wave environmental irradiance geometry (SOLWEIG) model is one of the state-of-the-art models frequently used for urban (micro-)climatic studies. Here, we present updated calculation schemes for SOLWEIG allowing the improved prediction of surface temperatures (wall and ground). We illustrate that parameterizations based on measurements of global radiation on a south-facing vertical plane obtain better results compared to those based on solar elevation. Due to the limited number of ground surface temperature parameterizations in SOLWEIG, we implement the two-layer force-restore method for calculating ground temperature for various soil conditions. To characterize changes in urban canyon air temperature (Tcan), we couple the calculation method as used in the Town Energy Balance (TEB) model. Comparison of model results and observations (obtained during field campaigns) indicates a good agreement between modeled and measured Tcan, with an explained variance of R2 = 0.99. Finally, we implement an energy balance model for vertically mounted PV modules to contrast different urban surface properties. Specifically, we consider (i) an environment comprising dark asphalt and a glass facade and (ii) an environment comprising bright concrete and a PV facade. The model results show a substantially decreased Tcan (by up to − 1.65°C) for the latter case, indicating the potential of partially reducing/mitigating urban heat island effects. [ABSTRACT FROM AUTHOR]