# Impact of Mining Disturbance on Highway Sustainability:
## 3 A Case Study
### Subsidence and Deformatons Impact on Highway
#### 3.5.4 Risk Assessment for Highway  
The predicted maximum subsidence and deformation values on the highway for all EPs are provided in Table 2.  
By comparing the predicted slope values (see Table 2), which are less than 8 mm/m (0.8%), with the allowed standard values of 25 mm/m (2.5%) in the direction of the road and 30-60 mm/m (3-6%) at a bend in the road, it can be concluded that there will be no traffic disturbances according to this parameter [87]. Based on the comparison of the predicted subsidence and deformation values with the allowed standard deformation values for the highway, it can be concluded that the radii of convex and concave curvatures exceed the allowable limits, and traffic disturbances regarding this parameter can be expected. In this particular case, due to the influence of the curvature, it is necessary to conduct special expertise with accompanying calculations regarding traffic safety to determine whether and how the technical norms and basic conditions of public transport on the highway change. These findings suggest that while vertical displacement and slope remain within acceptable ranges, the curvature variations could impact road safety by altering the road surface geometry, leading to potential driving discomfort or even structural degradation  
Figure 15: Subsidence curve, main slope, and curvature along the highway axis after mining out all excavation panels in the Southern District of the Morava Pit. over time. The exceeding of curvature limits necessitates further engineering assessments to determine whether mitigation measures, such as additional road reinforcement or realignment, may be required to ensure long-term highway stability. Mining beneath the highway implies technical supervision with surface displacement monitoring in the zone of excavation impact. By comparing the prognostic parameters of deformations (N, R) from Table 2 with the Polish general protection criteria for Category III facilities [51; 88], to which the highway belongs (\(5\prec\mathrm{N}\leq 10\) and \(12\succ R_{\mathrm{min}}\geq 6\)), the previously established vulnerability assessment of the E75 Belgrade-Nis highway (section Aleksinacki rudnici) due to potential coal mining is confirmed. Numerous case studies have been conducted in various mining regions worldwide to investigate the behavior of highways associated with coal mining activities. The most drastic example of the impact of longwall underground mining on the highway network is in Pennsylvania. Over the past five decades, longwall mining has become a highly efficient method for extracting coal, notably in Pennsylvania's Pittsburgh Coalbed. This process creates subsidence basins, causing ground sinking and significant horizontal strains. Despite over 600 extracted panels, the impact on highways and effective mitigation strategies remain under study [44; 45; 46]. Pennsylvan's experience with mining beneath interstate highways has shown that, while undermining roadways can be managed safely, subsidence effects can still cause severe damage to road surfaces. Over the past 40 years, mining has taken place beneath 25 interstate panels, yet substantial uncertainties remain regarding the best methods to control subsidence-related damage [46]. Reports estimate that the Pennsylvania government has invested nearly USD 20 million in monitoring and repairing sections of the I-79 affected by longwall mining [45]. Analysis of mined panels indicates that areas with lower overburden are more susceptible to surface disturbances and that the orientation of the highway relative to the mining operation influences the severity of damage. More in-depth investigations into both final and dynamic subsidence effects on highways are essential to comprehensively assess the risks associated with future underground mining beneath road infrastructures [46].