The dissertation proposed a methodology for detecting the threat to railway infrastructure by adjacent tree vegetation in the railway protection buffer zone. The methodology uses existing data sources from forestry and remote sensing.
The source for the threat assessment is characteristics such as the height of the tree vegetation, its species composition, and its health, as determined from satellite imagery. This dissertation proposed a formula for calculating the IVTIR - Improved Vegetation Threat Index for Railway infrastructure. The threat calculation was constructed as a weighted sum of tree height, species composition and health status of tree vegetation. The weights of the parameters in the formula for calculating IVTRI were determined based on a questionnaire survey among experts and then evaluated using the AHP method. The final values of the IVTIR index were classified into five categories: without danger, very low threat, low threat, medium threat and high threat.
The study assesses the threat in the railway protection zone for the whole territory of the Czech Republic. High and medium threats in the forested railway buffer zone were identified in 42.6% of its area in 2020. Based on comparing the IVTIR index values with the previous incidents caused by a tree fall or collision, two categories (medium threat and high threat) were identified as high risk. The remaining area contains vegetation that poses low or no risk. Nevertheless, its condition must continue to be monitored, as the threat level may increase, for example, due to deterioration in its health. Based on a comparison of actual occurrences of outliers and field investigation, the methodology developed to determine the level of threat to railroads by tree vegetation can be judged as well-designed.
The methodology aimed to design a threat detection procedure that would be easily sustainable and applicable, emphasising minimum potential costs. The methodology would allow status updates to be carried out regularly to respond to current developments.
The proposed methodology and the results can help the infrastructure manager identify vulnerable sites where corrective action should be taken. The application of methodology would improve safety and ensure the continuity of traffic even in extreme weather conditions. In addition to railways, the methodology can also be applied to other areas such as road transport, energy, and others.