Exploring the Impacts of Driving Environment on Crashes in Tunnel–Bridge–Tunnel Groups: An Eight-Zone Analytic Approach

Tunnel–bridge–tunnel groups (TBTGs) are emerging roads that often involve simple road alignments, but complex driving environments. Investigating crashes occurred in TBTGs is essential for revealing the environment–adaptability relationships such roads. This study seeks to analyze crash characteristics of component sections with different environments and compare impact differences key factor on crashes. After were defined through a proposed safety-critical distance metric determined via visual theory actual analyses, an eight-zone analytical method considering types lighting was developed probe into TBTGs. The results show proper distances bridge–tunnel tunnel–tunnel 150 500 m, respectively. In TBTGs, rate ordinary higher than bridges tunnels, particularly access zone. first passed tunnel witnesses proportion at zone transition second tunnel. influence bridge ratios related ratio type tunnels. findings presented herein can provide evidence-based guidance safety design management