Salt no longer travels through the Bohemian Forest along the Golden Trail, but halophytic neophytes do

The Golden Trail, used for the transport of salt from alpine mines to the Czech Kingdom for centuries, was a crucial ancient trade route in the Central European region. The contemporary road I/4, copying the Golden Trail, plays the same role today. The I/4 is used year round with deicing salt, a common standard, applied for winter maintenance. Deicing salt is often used, even in sections where the I/4 passes through the Bohemian Forest and its protected areas. The effects of applying deicing salts on ecosystems in the region is well documented. In addition to many other effects, high concentrations of salt along the roads cause significant changes in plant communities. Plant species sensitive to salinity disappear and the abundance of halophytes increases. Roads are also trajectories for the migration of neophytes. Seeds or other propagules are transported with cargo or in car tires. In this paper, we present our findings on the pilgrimage of Plantago coronopus, a true halophyte, into the Bohemian Forest. We also describe the species’ colonisation strategy and human measures supporting its successful migration in a region of high conservation value.

Comparison Of Winter Maintenance Requirements (Estonia, Latvia, Lithuania)

Three Baltic states are located next to each other on the coast of the Baltic Sea. Similarly, to Finland, density of population in these countries is low. All three countries have large amount of state roads with low traffic intensity. Climatic differences are minimal. Milder climate is in coastal area but inland the weather conditions are more severe. The average air temperature in January in Estonia is from -2 to -7 degrees Celsius but in Lithuania from -1 to -5 degrees Celsius. The number of snowy days fluctuates from 50 to 120. All three countries have common contracts for summer and winter maintenance where the responsibility for maintenance activities lays on the contractors. Despite common history the methods of the assignment of road maintenance contracts are different in every country. Estonia awards contracts in open tenders and has performance-based contracts. Latvia has the contract awarded to the State Joint Stock Company «Latvijas autoceļu uzturētājs» (“Latvian Road Maintainer”) by law and the contract is unit price based. Lithuania has the contract awarded to the state-owned company « Kelių priežiūra» the contract is performance-based. The requirements for road conditions are quite similar in all three countries. They have three levels of maintenance. High service level means snow and ice-free surface of the road pavement during winter in constant weather conditions and quick response in case of worsening road conditions. Medium service level means that snow and ice is allowed on the surface, but activities must be undertaken to improve skid resistance. The lowest service level means that snow and ice is allowed on the surface and activities to improve skid resistance (mostly only snow cleaning) may be undertaken in some spots only. In Estonia the expenses for winter maintenance are lower than in the neighbouring countries but it does not have impact on traffic safety during winter.

Review of Reduced Salt, Snow, and Ice Management Practices for Commercial Businesses

Chlorides (frequently sodium chloride) are used to improve safety and access to roads and other surfaces in winter. However, chlorides also pose risks to aquatic life and raises human health concerns as they move to surface waterbodies and infiltrate groundwater. In response, many government bodies have adopted winter maintenance best management practices (BMPs) that reduce the amount of chlorides used while providing service and safety. Commercial businesses maintaining parking lots, driveways, and other surfaces have been shown to contribute as much as 50% of the chloride loads to local waterbodies in some areas, but less is known about the potential benefits of private contractors to implement similar BMPs. In addition, many existing resources on the topic are designed for municipal audiences, creating a knowledge gap about the feasibility of private companies to adopt these practices. The authors identified 14 BMPs common to municipal plans with the potential to be adopted by private contractors through a literature review. These practices aim to increase the efficiency of salt applications, and/or decrease environmental impacts while delivering a similar level of service and cost over time. The authors considered potential barriers and benefits to private contractors adopting and using these BMPs. Benefits included reduced liability (e.g., risk of lawsuits), costs, environmental impacts, and improved service. Barriers included additional staff time and training, increased materials, equipment, and maintenance costs. Additional research is needed to ground-truth these predicted motivations and barriers; a greater understanding of private contractor behaviors can enhance educational efforts that promote reduced salt practices.

Improving the Temperature Sensitivity of Bitumen for Emergency Pavement Repair

The quality of asphalt pavement maintenance depends on several important factors, including the selection of patching materials and choice of repair technique. Conventional hot mix plants operate to support large paving projects, and economy favors high-volume output. When repairs and maintenance are needed it can be challenging to maintain small quantities of hot bituminous mixtures at a sufficient temperature, especially in the case of winter maintenance and consequently the repair materials cannot be compacted to the desired level in some occasions. The temperature sensitivity plays a significant factor to understand the asphalt pavement failures and indicates how quickly asphalt properties change over time in terms of indices such as penetration index. Therefore, this research aims to develop a polymer-modified binder with reduced temperature sensitivity, and it can be used for hand-laid application in small quantities for emergency winter repair and maintenance. The results showed that the highest penetration index has been achieved by modifying bitumen with 20% rubber and 2% wax, which is reduced the temperature sensitivity by 168%. Additionally, the Fourier Transform Infrared Spectroscopy (FTIR) test and X-Ray Diffraction (XRD) test were conducted to monitor the changes in the chemical composition and identify crystalline phases of polymer modified binder from the aspect of functional groups. It is indicated that the bitumen, rubber, and wax react chemically to build 3D networks that have an interlaced form in the bitumen matrix resulting in reduced temperature sensitivity of the polymer modified binder.

Winter Road Surface Conditions Classification using Convolutional Neural Network (CNN): Visible Light and Thermal Images Fusion

In winter, road conditions play a crucial role in traffic flow efficiency and road safety. Icy, snowy, slushy, or wet road conditions reduce tire friction and affect vehicle stability which could lead to dangerous crashes. To keep traffic operations safe, cities spend a significant budget on winter maintenance operations such as snow plowing and spreading salt/sand. This paper proposes a methodology for automated winter road surface conditions classification using Convolutional Neural Network and the combination of thermal and visible light cameras. As part of this research, 4,244 pairs of visible light and thermal images are captured from pavement surfaces and classified into snowy, icy, wet, and slushy surface conditions. Two single-stream CNN models (visible light and thermal streams), and one dual-stream CNN model are developed. The average F1-Score of dual-stream model is 0.866, 0.935, 0.985, and 0.888 on snowy, icy, wet, and slushy, respectively. The weighted average F1-Score is 0.94.

Monitoring of The Impact of Road Salting On Spruce Forest Ecosystem In The Vicinity of The Highway D1 In The Bohemian-Moravian Highlands, Czech Republic

Monitoring of pollution in the vicinity of roads connected to winter road maintenance is one of the important tools for optimising winter maintenance technology and reducing its environmental impact. The aim of this study was to determine the relationship between winter road maintenance and the increased concentration of sodium ion to characterize the harm caused by the de-icing agents on selected types of individual components grown in the Norway Spruce ecosystem. The model area is located in the immediate vicinity of the D1 motorway connecting Prague and Brno (Czech Republic), at 103rd kilometer. The area is thus exposed to long-term contamination from automobile transport and the monitoring was carried out for three consecutive years. A clear effect of the de-icing agents on conifers near the road has been demonstrated by the symptoms of salt damage visually observed in close proximity to the road (at a sampling distance of 5 m). The needles of these spruce trees also showed increased sodium concentrations, regardless of the age of the needles. The study also confirms that sodium accumulates in all selected components of the analysed ecosystem (moos, humus, soil). The sodium concentration has been found to decrease with increasing distance from the road for all of the components.