With the emergence of the COVID-19 pandemic, passenger preferences for transportation modes and transportation management strategies have rapidly changed in the last few years. In this study, field research was conducted to reveal the behaviors and perceptions of passengers before and during the COVID-19 pandemic in Izmir city of Turkey. A total of 1437 participants were asked to evaluate the pre and during pandemic periods with their frequency of use for different types of transportation modes in Izmir. When the results of the study were evaluated holistically, it was revealed that the participants used environmentally friendly transportation modes such as bicycles and e-bikes more than before the pandemic and that they wanted to use them after the pandemic. Despite this, it is seen that the use of taxis and private vehicles has increased during the pandemic, especially for long-distance trips, and the use of public transport and light rail systems (LRS) in general has decreased. Nearly half of respondents (49.7%) said bus drivers did not use adequate protective equipment during the pandemic. In addition, 41.1% of the participants stated that the HES code application was not applied adequately in public transportation. In the study, it was also revealed that the practice of reducing the number of operational public transport vehicles during the pandemic was found to be negative by the participants.

This study’s primary objective is to determine how boron-containing wastes from the stripping areas of the Emet–Bigadiç (Türkiye) boron deposits affect the mechanical performance of cement-based mortars and the effectiveness of weak soil improvement. The Bigadiç samples contain colemanite, calcite, dolomite, and quartz minerals, whereas the Emet samples predominantly comprise calcite. The wastes were incorporated into the cement matrix in two different forms: (i) solid-phase cement replacement and (ii) boron waste solution additive. Experimental findings demonstrated that replacing 10% of cement with a 4% Bigadiç-origin boron waste solution resulted in a compressive strength of 55.37 MPa after 7 days of curing, which is higher than that of the reference mixture. Also, the study revealed that the addition of 15% boron waste to weak soils increased the soil density to 1728 kg/m³ by filling micro-voids and enhancing intergranular interlocking. Due to this physical filling and chemical bridging effect, CBR value increased from an initial 4 to 6, providing a significant improvement in the soil’s deformation modulus and bearing capacity. Consequently, used boron wastes not only provide high mechanical performance in cement-based systems but also offer potential as an alternative additive material for sustainable and cost-effective soil stabilization applications.

A localized landslide that occurred on a specific section of the road to the Uluyazı Campus of Çankırı Karatekin University seriously threatened road safety and disrupted transportation continuity. In this study, the ground conditions of the landslide area were examined in detail. Soil parameters were determined through field observations, drilling, Standard Penetration Test (SPT) data, laboratory experiments, liquefaction potential, bearing capacity, and consolidation behaviour were analysed. The analyses showed that the soil was safe in terms of liquefaction and that the bearing capacity was at a level suitable for road construction and use. However, consolidation settlements and dissolutions in gypsum levels were identified as critical factors that could trigger landslides. To prevent landslides and ensure road safety, double rows of bored piles with a diameter of ∅120 cm, a length of 35 m, and spaced at 1.4 m intervals were connected with a cap beam. This engineering measure cut the landslide surface, limited road deformations, and ensured transportation safety. The study demonstrated the effectiveness of bored pile applications in formations where soil-water interaction was significant and offered an applicable solution for critical areas in highway engineering.