The 4,100 meter-long tunnel passes wholly under Maynard Mountain.
Cars heading to Whittier are allowed every half hour while cars leaving Whittier can enter the tunnel every hour.
In between regularly scheduled passenger trains are also accommodated.
The tunnel also contains several turnaround spots, which are reserved for disabled vehicles.
As many as 450 vehicles can wait outside for passing through.
A southbound train exits the Anton Anderson Memorial Tunnel.
