The Zion-Mount Carmel Tunnel
Construction of the 1.1 mile Zion-Mount Carmel Tunnel began in the late 1920's and was completed in 1930. At the time that the tunnel was dedicated, on July 4, 1930, it was the longest tunnel of it's type in the United States. The purpose of the building the Zion-Mount Carmel Tunnel (and the Zion-Mount Carmel Highway) was to create direct access to Bryce Canyon and Grand Canyon from Zion National Park.
Tunnel Traffic Control for Oversize Vehicles
Before 1989, large vehicles, including tour buses, motor homes, and trailers, were involved in more and more accidents and near misses in the tunnel due to an immense increase in the volume of traffic and in the size of vehicles passing through the tunnel.
A study by the Federal Highways Administration in early 1989 found that large vehicles could not negotiate the curves of the tunnel without crossing the center line. To ensure safety, the National Park Service began traffic control ("Escorts") at the tunnel in the spring of that year.
Rangers posted at both ends of the tunnel convert two-way tunnel traffic to one-way for larger vehicles, ensuring safe passage. This service, for which a $15 dollar tunnel permit fee is charged, was provided for over 27,874 oversized vehicles in calendar year 2011.
During the winter months, drivers of large vehicles must make advance arrangements at the entrance stations for traffic control ("Escorts") at the tunnel. Winter hours of operations for the tunnel are 8:00 a.m. to 4:30 p.m. seven days a week.