Due to the long history of rockslides and land slippage, Kiewit constructed tunnels to bypass the Devil's Slide portion of Route 1 so motorists can avoid these major slide areas. Using the New Austrian Tunneling Method, which relies on inherent rock strength for support, crews constructed the tunnels through granitic, sandstone and shale formations. The tunnels are approximately 4,100 feet long, 30 feet wide, 22 feet high and 60 feet apart.
The Central Artery/Tunnel has the capacity to carry 250,000 daily vehicles. To ensure the safety of motorists, crews installed a system-wide security system that includes perimeter video surveillance, an access control system, an instruction detection system, a security operator console, motion detection and telephone communication.