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Crash injuries not only result in huge property damages, physical distress, and loss of lives, but arouse a reduction in roadway capacity and delay the recovery progress of traffic to normality. To assess the resilience of post-crash tunnel traffic, two novel concepts, i.e., surrogate resilience measure (SRM) and injury-based resilience (IR), were proposed in this study. As a special kind of semi-closed infrastructure, urban tunnels are more vulnerable to traffic crashes and injuries than regular roadways. To assess the IR of the post-crash roadway tunnel traffic system, an over-one-year accident dataset comprising 8621 crashes in urban roadway tunnels in Shanghai, China was utilized. A total of 34 variables from 11 factors were selected to establish the IR assessment indicator system. Methodologically, to tackle the skewness issue in the dataset, a binary skewed logit (Scobit) model was found to be superior to a conventional logistic model and subsequently adopted for further analysis. The estimated results showed that 15 variables were identified to be significant in assessing the IR of the roadway tunnels in Shanghai. Finally, the formula for calculating the IR levels of post-crash traffic systems in tunnels was given and would be a helpful tool to mitigate potential trends in crash-related resilience deterioration. The findings of this study have implications for bridging the gap between conventional traffic safety research and system resilience modeling.

The tunnel width and the transverse fire’s position both impact the heat exhaust coefficient, which is a critical component of the lateral smoke exhaust in tunnel fires. In this research, the tunnel width and the transverse location of the fire source are varied to analyze the heat exhaust coefficient of lateral smoke exhaust. When tunnel width increases, there is a noticeable decrease in the longitudinal temperature of the entrained air and smoke layer in the fire plume. Furthermore, the heat exhaust coefficients are reduced. An increase in the distance between the exhaust vent and the fire source causes an increase in the proportion of hot smoke in the smoke exhaust mass flow, which increases the heat exhaust coefficient. A calculated heat exhaust coefficient was developed using the fire source’s location and the tunnel’s width as inputs, which agrees well with the simulation results. This method can predict the heat exhaust coefficient of the lateral smoke exhaust in tunnel fires. The findings of this study provide insight into how the tunnel width and the location of a transverse fire influence the heat exhaust coefficient.

Plug-holing of the smoke layer is an unfavorable phenomenon for the smoke extraction efficiency in the naturally ventilated tunnel with vertical shaft. In this work, theoretical analysis and large eddy simulation (LES) are carried out to investigate how to prevent the occurrence of the plug-holing phenomenon and improve smoke extraction efficiency. The results show that the occurrence of plug-holing is influenced by the height, cross-sectional area and total pressure loss coefficient of the vertical shaft, as well as the thickness of the smoke layer. A modified dimensionless number Fr* is proposed to represent the proportion of smoke in the exhausted mass flow. Fr* varies as the −1/4 power of the cross-sectional area of the shaft, −1/2 power of the height of the shaft, and increases linearly with the thickness of the smoke layer. The critical value of Fr* for predicting whether the plug-holing phenomenon occurs is determined to be 0.34 by combining the results of the previous small-scale experiment. In addition, a smoke reservoir is designed under the shaft to increase the thickness of the smoke layer, which is proven to be effective in preventing the occurrence of the plug-holing phenomenon and improving the smoke extraction efficiency of the vertical shaft. The findings of this paper contribute to the understandings of smoke extraction for naturally ventilated tunnel with vertical shaft, and the results are also useful to the fire protection engineering in tunnels.