Traffic accidents at urban intersections represent a major road safety concern, particularly those caused by traffic signal violations. To analyze accident mechanisms and develop effective prevention strategies, this study employs a cellular automata model to investigate the relationship between accident probability $P_{ac}$ and traffic parameters at signalized intersections. Simulation results reveal a nonlinear relationship between Pac and traffic demand. The accident probability reaches a maximum under free-flow conditions and subsequently decreases as congestion increases, eventually stabilizing at a nearly constant level under highly congested traffic. Additionally, collision risk increases with lane-changing probability $P_{chg}$, especially upstream of the intersection. High traffic speeds significantly elevate both accident probability and severity. Finally, the results indicate that extending traffic signal cycle durations is not an effective strategy for reducing accident risk. Overall, the proposed model provides a useful framework for estimating accident risk under different traffic conditions and supporting traffic management, including control decisions aimed at improving road safety.

Our study aimed to assess air quality within buildings constructed with coal ash concrete, with a specific focus on radon measurement. Coal ash, a by-product of the TAQA Morocco thermal power plant. In this investigation, two concrete mixtures were prepared. It is possible that concrete produced from coal ash may contain elevated levels of radon, a naturally occurring radioactive gas that could prove detrimental to human health, given that coal ash contains considerable quantities of radioactive elements. To this regard, two nuclear techniques were employed for analysis: high-resolution gamma spectrometry and alpha dosimetry based on the use of LR115 on the two concrete mixes. The equivalent radium activity (Ra_eq), internal (H_in) and external (H_ex) risk indices, absorbed dose rate (Ḋ), annual effective dose (Ė) and excess lifetime cancer risk (ELCR) were also calculated. The surface (E_S) and mass (E_M) radon exhalation rates were calculated for the analysed samples in order to assess the radiological risks resulting from the use of coal ash concrete.The results has revealed no evidence of any health risks to the general public, and therefore coal ash concrete can be used in construction projects.