The SR 99 tunnel will be approximately two miles long. It will feature two 11-foot travel lanes in each direction, bordered by an eight-foot safety shoulder and a two-foot shoulder. Long, gentle curves will allow for safe sight distances. The southbound lanes are stacked above the northbound lanes, so drivers will not see oncoming traffic.
The tunnel will be built to modern earthquake standards. There will be no on- or off-ramps between the two tunnel portals. In the event of an emergency, exits every 650 feet provide shelter and escape routes, while a state-of-the-art safety and ventilation system assists first responders, and fights fire and fumes. (Read more about the tunnel's safety systems in the program library.)