How do you know it’s safe to tunnel beneath the viaduct?

Tags: winter-closure

Our team has extensive experience tunneling in dense urban areas. Some of our crew members successfully built a nearly 40-foot diameter tunnel six feet beneath the famed La Sagrada Familia cathedral in Barcelona. The mitigation techniques that were used successfully during that project, including building angled walls beneath the structure’s foundation, are being used during SR 99 tunnel construction. Sound Transit has successfully tunneled through similar ground conditions and beneath a number of major roadways in the area, including I-5 and SR 520.